Unit 2

1) What is VIEW? Explain how to create and modify Views?

View in Android

A View in Android is a UI component that is used to display and interact with elements in an application. Examples of Views include Button, TextView, EditText, ImageView, etc. All Views are subclasses of the android.view.View class.

Creating a View

Using XML (Recommended)

Define a View in an XML layout file (res/layout/activity_main.xml).

Example:


<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello, Android!" />

Using Java/Kotlin Code

Create a View dynamically in the MainActivity.java.

Example (Java):


TextView textView = new TextView(this);
textView.setText("Hello, Android!");
textView.setLayoutParams(new LinearLayout.LayoutParams(
    LinearLayout.LayoutParams.WRAP_CONTENT,
    LinearLayout.LayoutParams.WRAP_CONTENT));

Modifying a View

Changing View Properties in Java

Modify a View dynamically in code.

Example:


TextView textView = findViewById(R.id.textView);
textView.setText("Updated Text");
textView.setTextSize(20);
textView.setTextColor(Color.RED);

Handling User Interaction

Set an onClickListener to respond to user actions.

Example:


Button button = findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        textView.setText("Button Clicked!");
    }
});

Conclusion

Views are building blocks of UI design in Android. They can be created, modified, and interacted with using XML or Java/Kotlin code to build interactive applications.

2) Explain the concept of Datepicker and Timepicker.

DatePicker and TimePicker in Android

DatePicker and TimePicker are UI components in Android that allow users to select a date or time in an intuitive way.

1. DatePicker

Used to select a date (day, month, year).
Can be displayed as:
- DatePickerDialog (popup dialog).
- DatePicker Widget (embedded in the layout).

Example: DatePickerDialog in Java


// Open DatePickerDialog when button is clicked
Button btnSelectDate = findViewById(R.id.btnSelectDate);
btnSelectDate.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Calendar calendar = Calendar.getInstance();
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        int day = calendar.get(Calendar.DAY_OF_MONTH);
 
        DatePickerDialog datePickerDialog = new DatePickerDialog(MainActivity.this,
            (view, selectedYear, selectedMonth, selectedDay) -> {
                // Set selected date in TextView
                TextView dateTextView = findViewById(R.id.dateTextView);
                dateTextView.setText(selectedDay + "/" + (selectedMonth + 1) + "/" + selectedYear);
            }, year, month, day);
 
        datePickerDialog.show();
    }
});

2. TimePicker

Used to select a time (hour, minute).
Can be displayed as:
- TimePickerDialog (popup).
- TimePicker Widget (in the layout).
Supports 12-hour or 24-hour format.

Example: TimePickerDialog in Java


// Open TimePickerDialog when button is clicked
Button btnSelectTime = findViewById(R.id.btnSelectTime);
btnSelectTime.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Calendar calendar = Calendar.getInstance();
        int hour = calendar.get(Calendar.HOUR_OF_DAY);
        int minute = calendar.get(Calendar.MINUTE);
 
        TimePickerDialog timePickerDialog = new TimePickerDialog(MainActivity.this,
            (view, selectedHour, selectedMinute) -> {
                // Set selected time in TextView
                TextView timeTextView = findViewById(R.id.timeTextView);
                timeTextView.setText(selectedHour + ":" + selectedMinute);
            }, hour, minute, true);
 
        timePickerDialog.show();
    }
});

Conclusion

DatePicker is used to select a date, while TimePicker is used to select a time.
Both can be implemented using dialogs or UI widgets.
These components improve user experience by providing a structured way to input dates and times.

3) Explain the term localization in Android with example.

Localization in Android

Localization in Android refers to the process of adapting an application for different languages, regions, and cultures. It helps in making an app accessible to a global audience by providing text, images, and other resources in different languages.

Key Features of Localization

Supports Multiple Languages – Users can view the app in their preferred language.
Region-Specific Formatting – Handles date, time, currency, and number formats.
Uses Resource Files – Stores text in res/values/ folders to support different languages.

Steps for Implementing Localization

Define Default Strings in res/values/strings.xml


<resources>
    <string name="app_name">My Application</string>
    <string name="greeting">Hello, Welcome!</string>
</resources>

Create Language-Specific strings.xml Files

For French (res/values-fr/strings.xml)


<resources>
    <string name="app_name">Mon Application</string>
    <string name="greeting">Bonjour, Bienvenue!</string>
</resources>

For Spanish (res/values-es/strings.xml)


<resources>
    <string name="app_name">Mi Aplicación</string>
    <string name="greeting">Hola, ¡Bienvenido!</string>
</resources>

Android Automatically Detects User Language
- If the device language is French, Android loads values-fr/strings.xml.
- If the language is not supported, the default values/strings.xml is used.

Using Localized Strings in Code


TextView textView = findViewById(R.id.textView);
textView.setText(getString(R.string.greeting));

Conclusion

Localization in Android allows apps to adapt to different languages and regions, improving user experience and expanding the app’s global reach.

4) Explain how to listen Native Broadcast Intents.

Listening to Native Broadcast Intents in Android

Broadcast Intents are messages sent by the Android system or applications to notify components about specific events. Native Broadcast Intents are system-generated broadcasts (e.g., battery status, network changes).

To listen to Native Broadcast Intents, we use a BroadcastReceiver, which responds when the system sends a broadcast.

Steps to Listen to Native Broadcast Intents

1. Create a BroadcastReceiver Class

Define a BroadcastReceiver that listens for system events.
Example: Listening for battery level changes.


import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
 
public class BatteryReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        int level = intent.getIntExtra("level", -1); // Get battery level
        Toast.makeText(context, "Battery Level: " + level + "%", Toast.LENGTH_SHORT).show();
    }
}

2. Register the Receiver in `AndroidManifest.xml`

Add the receiver inside the <application> tag.


<receiver android:name=".BatteryReceiver">
    <intent-filter>
        <action android:name="android.intent.action.BATTERY_CHANGED"/>
    </intent-filter>
</receiver>

3. Register Receiver Dynamically in Activity (Optional)

Instead of declaring in AndroidManifest.xml, you can register it in an activity.


BatteryReceiver batteryReceiver = new BatteryReceiver();
 
@Override
protected void onResume() {
    super.onResume();
    IntentFilter filter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
    registerReceiver(batteryReceiver, filter);
}
 
@Override
protected void onPause() {
    super.onPause();
    unregisterReceiver(batteryReceiver);
}

Common Native Broadcast Intents

Intent Action	Description
`android.intent.action.BATTERY_CHANGED`	Battery level or state change.
`android.net.conn.CONNECTIVITY_CHANGE`	Network connectivity change.
`android.intent.action.AIRPLANE_MODE`	Airplane mode enabled/disabled.
`android.intent.action.POWER_CONNECTED`	Device connected to power.
`android.intent.action.POWER_DISCONNECTED`	Device disconnected from power.

Conclusion

Listening to Native Broadcast Intents allows apps to respond to system events like battery status, network changes, and power connections, improving app functionality and user experience.

5) Explain the concept of Download Manager.

Download Manager in Android

Download Manager is an Android system service that handles long-running downloads in the background. It allows applications to download files efficiently while handling network failures, system reboots, and retries automatically.

Features of Download Manager

Handles Large File Downloads – Efficiently downloads large files without freezing the UI.
Supports Background Downloading – Runs downloads in the background, allowing users to continue using the app.
Automatic Retry & Resume – Resumes interrupted downloads due to network failures or system reboots.
Manages Download Notifications – Shows progress in the notification bar.
Supports Various Network Conditions – Can restrict downloads to Wi-Fi only.

Using Download Manager in Android

1. Add Permission in `AndroidManifest.xml`


<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

2. Start a File Download


import android.app.DownloadManager;
import android.content.Context;
import android.net.Uri;
import android.os.Environment;
 
public void startDownload(Context context) {
    DownloadManager downloadManager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
 
    Uri uri = Uri.parse("https://example.com/sample.pdf"); // File URL
 
    DownloadManager.Request request = new DownloadManager.Request(uri);
    request.setTitle("Downloading File");
    request.setDescription("Downloading sample.pdf");
    request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "sample.pdf");
    request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
 
    if (downloadManager != null) {
        downloadManager.enqueue(request);
    }
}

3. Monitor Download Progress

To track download status, register a BroadcastReceiver.


import android.app.DownloadManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
 
public class DownloadReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        long downloadId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
        Toast.makeText(context, "Download Completed! ID: " + downloadId, Toast.LENGTH_SHORT).show();
    }
}


registerReceiver(new DownloadReceiver(), new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));

Use Cases of Download Manager

Downloading PDFs, images, or videos in apps.
Updating files in the background for offline access.
Handling large downloads without affecting app performance.

Conclusion

Download Manager simplifies downloading large files by handling background tasks, failures, and progress tracking, ensuring a smooth user experience.

Android provides three types of menus to display options and actions in an application. These menus help improve user interaction and navigation.

The primary menu for an activity, displayed in the toolbar/action bar.
Typically used for settings, search, or common actions.
Appears when the user taps the three-dot menu.

Step 1: Define Menu in XML (res/menu/menu_main.xml)


<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/action_settings"
        android:title="Settings"
        android:showAsAction="never"/>
    <item android:id="@+id/action_search"
        android:title="Search"
        android:showAsAction="ifRoom"/>
</menu>

Step 2: Load Menu in Activity (MainActivity.java)


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

A floating menu that appears on long press of a UI element.
Used for actions related to a specific item, like edit, delete, or share.

Step 1: Register View for Context Menu (MainActivity.java)


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 
    TextView textView = findViewById(R.id.textView);
    registerForContextMenu(textView);
}

Step 2: Create Context Menu (MainActivity.java)


@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
    super.onCreateContextMenu(menu, v, menuInfo);
    menu.setHeaderTitle("Select Action");
    menu.add(0, v.getId(), 0, "Edit");
    menu.add(0, v.getId(), 0, "Delete");
}

A temporary menu that appears next to a clicked view.
Used for quick actions like selecting an item or sharing content.

Step 1: Create Popup Menu in Java (MainActivity.java)


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 
    Button button = findViewById(R.id.button);
    button.setOnClickListener(v -> {
        PopupMenu popup = new PopupMenu(MainActivity.this, v);
        popup.getMenuInflater().inflate(R.menu.menu_popup, popup.getMenu());
        popup.show();
    });
}

Step 2: Define Menu Items (res/menu/menu_popup.xml)


<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/action_share"
        android:title="Share"/>
    <item android:id="@+id/action_favorite"
        android:title="Add to Favorites"/>
</menu>

Comparison of Menus

Menu Type	How It Appears	Use Case
Options Menu	In the toolbar (three-dot menu)	App-wide actions like Settings, Search
Context Menu	On long press of an item	Item-specific actions like Edit, Delete
Popup Menu	Next to a clicked view	Quick actions like Share, Add to Favorites

Conclusion

Android menus enhance user experience by providing structured ways to navigate, interact, and perform actions within an app.

7) Explain spinner in detail with pseudo code.

Spinner in Android

A Spinner in Android is a dropdown UI component that allows users to select one option from a list. It is similar to a dropdown menu in web development.

Features of Spinner

Dropdown List – Displays a list of selectable items.
Default Selection – Shows the first item by default.
Customizable Appearance – Can be styled using custom adapters.
Efficient UI Component – Saves space compared to RadioButtons.

Steps to Implement a Spinner

1. Define Spinner in XML Layout (`res/layout/activity_main.xml`)


<Spinner
    android:id="@+id/spinner"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

2. Create and Set Data in Java (`MainActivity.java`)


import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
 
public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // Step 1: Initialize Spinner
        Spinner mySpinner = findViewById(R.id.spinner);
 
        // Step 2: Define data for Spinner (Dropdown items)
        String[] items = {"Option 1", "Option 2", "Option 3", "Option 4"};
 
        // Step 3: Create an ArrayAdapter to link data with Spinner
        ArrayAdapter<String> adapter = new ArrayAdapter<>(
            this,
            android.R.layout.simple_spinner_item,
            items
        );
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
 
        // Step 4: Set Adapter to Spinner
        mySpinner.setAdapter(adapter);
 
        // Step 5: Handle item selection from Spinner
        mySpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                String selectedItem = parent.getItemAtPosition(position).toString();
                Toast.makeText(MainActivity.this, "Selected: " + selectedItem, Toast.LENGTH_SHORT).show();
            }
 
            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                // Do nothing if no item is selected
            }
        });
    }
}

Explanation

Define Spinner in XML – Adds a Spinner component to the UI.
Create Data Source – Defines a list of selectable options.
Use an ArrayAdapter – Binds the list to the Spinner.
Set the Adapter – Attaches the adapter to the Spinner.
Handle Selection Events – Uses setOnItemSelectedListener() to capture user selection.

Conclusion

A Spinner is a user-friendly dropdown component that allows users to select one item from a list. It improves UI efficiency and is commonly used for form inputs, filters, and settings menus.

8) Write down the pseudo code for Radio button and Checkbox.

Pseudo Code for RadioButton and CheckBox in Android

1. RadioButton in Android

A RadioButton allows users to select only one option from a group.

XML Layout for RadioButton (`activity_main.xml`)


<RadioGroup
    android:id="@+id/radioGroup"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
 
    <RadioButton
        android:id="@+id/radioButton1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Option 1" />
 
    <RadioButton
        android:id="@+id/radioButton2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Option 2" />
</RadioGroup>
 
<Button
    android:id="@+id/submitButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Submit"/>

Java Code for RadioButton (`MainActivity.java`)


import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
 
public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // Initialize RadioGroup and Button
        RadioGroup radioGroup = findViewById(R.id.radioGroup);
        Button submitButton = findViewById(R.id.submitButton);
 
        // Handle Button Click
        submitButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int selectedId = radioGroup.getCheckedRadioButtonId();
                if (selectedId != -1) {
                    RadioButton selectedRadioButton = findViewById(selectedId);
                    Toast.makeText(MainActivity.this, "Selected: " + selectedRadioButton.getText(), Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(MainActivity.this, "No selection made", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

2. CheckBox in Android

A CheckBox allows users to select multiple options independently.

XML Layout for CheckBox (`activity_main.xml`)


<CheckBox
    android:id="@+id/checkBox1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Option 1"/>
 
<CheckBox
    android:id="@+id/checkBox2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Option 2"/>
 
<Button
    android:id="@+id/submitButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Submit"/>

Java Code for CheckBox (`MainActivity.java`)


import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
 
public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // Initialize CheckBoxes and Button
        CheckBox checkBox1 = findViewById(R.id.checkBox1);
        CheckBox checkBox2 = findViewById(R.id.checkBox2);
        Button submitButton = findViewById(R.id.submitButton);
 
        // Handle Button Click
        submitButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                StringBuilder result = new StringBuilder("Selected: ");
                if (checkBox1.isChecked()) {
                    result.append(checkBox1.getText()).append(" ");
                }
                if (checkBox2.isChecked()) {
                    result.append(checkBox2.getText()).append(" ");
                }
                if (result.toString().equals("Selected: ")) {
                    result.append("None");
                }
                Toast.makeText(MainActivity.this, result.toString(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}

Conclusion

RadioButton allows only one selection from a group.
CheckBox allows multiple selections independently.
Both can be used to capture user preferences in Android apps.

9) Explain Checkbox in Android with example.

CheckBox in Android

A CheckBox in Android is a UI component that allows users to select multiple options independently. It is useful for cases where users may choose more than one option, such as selecting preferences, settings, or features.

Features of CheckBox

Multiple Selection – Users can select one or more options.
Independent State – Each checkbox operates separately.
Two-State Behavior – A checkbox can be checked (true) or unchecked (false).
Custom Styling – Checkboxes can be styled with custom colors and images.

Example: Implementing CheckBox in Android

1. Define CheckBoxes in XML (`activity_main.xml`)


<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">
 
    <CheckBox
        android:id="@+id/checkBox1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Option 1" />
 
    <CheckBox
        android:id="@+id/checkBox2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Option 2" />
 
    <Button
        android:id="@+id/submitButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Submit"/>
</LinearLayout>

2. Handle CheckBox Selection in Java (`MainActivity.java`)


import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
 
public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // Initialize CheckBoxes and Button
        CheckBox checkBox1 = findViewById(R.id.checkBox1);
        CheckBox checkBox2 = findViewById(R.id.checkBox2);
        Button submitButton = findViewById(R.id.submitButton);
 
        // Handle Button Click
        submitButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                StringBuilder result = new StringBuilder("Selected: ");
                if (checkBox1.isChecked()) {
                    result.append(checkBox1.getText()).append(" ");
                }
                if (checkBox2.isChecked()) {
                    result.append(checkBox2.getText()).append(" ");
                }
                if (result.toString().equals("Selected: ")) {
                    result.append("None");
                }
                Toast.makeText(MainActivity.this, result.toString(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}

Explanation

CheckBoxes are defined in XML – Users can select multiple options.
Initialize CheckBoxes in Java – Retrieve their state using isChecked().
Handle Button Click – Display selected options using Toast.

Use Cases of CheckBox

Selecting multiple interests/preferences (e.g., “Sports”, “Music”, “Movies”).
Enabling/disabling features in an app (e.g., “Enable Notifications”, “Dark Mode”).
Accepting terms and conditions before proceeding.

Conclusion

A CheckBox in Android provides an easy way to select multiple options. It enhances user interaction by allowing customizable selections in forms, settings, and preference screens.

10) Explain Edit text in Android with example.

EditText in Android

EditText is an Android UI component that allows users to input text in an application. It is commonly used for forms, login screens, and user feedback sections.

Features of EditText

User Input – Allows users to type text.
Customizable Input Type – Supports text, numbers, passwords, email, etc.
Hint Text – Displays a placeholder inside the text field.
Validation Support – Can restrict input length and format.
Auto-Correction & Suggestions – Supports predictive text.

Example: Implementing EditText in Android

1. Define EditText in XML (`activity_main.xml`)


<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">
 
    <EditText
        android:id="@+id/editTextName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter your name"
        android:inputType="textPersonName" />
 
    <Button
        android:id="@+id/submitButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Submit"/>
</LinearLayout>

2. Handle EditText Input in Java (`MainActivity.java`)


import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
 
public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // Initialize EditText and Button
        EditText editTextName = findViewById(R.id.editTextName);
        Button submitButton = findViewById(R.id.submitButton);
 
        // Handle Button Click
        submitButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = editTextName.getText().toString().trim();
                if (!name.isEmpty()) {
                    Toast.makeText(MainActivity.this, "Hello, " + name + "!", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(MainActivity.this, "Please enter your name", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

Explanation

EditText in XML – Accepts user input with a placeholder (hint).
Retrieve Text in Java – editText.getText().toString() gets the input.
Validate Input – Ensures the field is not empty before showing a message.
Display Input Using Toast – Shows a greeting message with the entered name.

Common Input Types in EditText

Input Type	Description
`textPersonName`	Name input
`textEmailAddress`	Email input
`phone`	Phone number input
`number`	Numeric input
`textPassword`	Password input (hidden characters)

Use Cases of EditText

Login and Registration Forms – Accept usernames, passwords, and emails.
Search Fields – Allow users to search content in an app.
Feedback Forms – Collect user comments and reviews.

Conclusion

EditText is a key UI component for user input in Android apps. It supports different input types, validation, and customization, making it suitable for various applications.

11) Explain Text view in Android with example.

TextView in Android

TextView is a UI component in Android used to display static or dynamic text on the screen. It does not allow user input like EditText but is commonly used for labels, headings, and displaying messages.

Features of TextView

Displays Read-Only Text – Used for labels, descriptions, and instructions.
Supports Styling – Can change font size, color, style, and alignment.
Dynamic Text Update – Can update text programmatically.
Supports Click Events – Can detect clicks using setOnClickListener().

Example: Implementing TextView in Android

1. Define TextView in XML (`activity_main.xml`)


<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">
 
    <TextView
        android:id="@+id/textViewMessage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello, Android!"
        android:textSize="20sp"
        android:textColor="#000000"
        android:padding="10dp" />
 
    <Button
        android:id="@+id/buttonChangeText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Change Text"/>
</LinearLayout>

2. Modify TextView Programmatically (`MainActivity.java`)


import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
 
public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // Initialize TextView and Button
        TextView textViewMessage = findViewById(R.id.textViewMessage);
        Button buttonChangeText = findViewById(R.id.buttonChangeText);
 
        // Handle Button Click to Change TextView Content
        buttonChangeText.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                textViewMessage.setText("Text Updated!");
            }
        });
    }
}

Explanation

TextView in XML – Displays default text, styled with size, color, and padding.
Modify Text in Java – textView.setText("New Text") updates the displayed text.
Button Click Listener – Changes text dynamically when the button is clicked.

Common Properties of TextView

Property	Description
`android:text`	Sets the default text.
`android:textSize`	Defines text size (e.g., `16sp`).
`android:textColor`	Sets text color (e.g., `#FF0000` for red).
`android:textStyle`	Makes text bold, italic, or normal.
`android:gravity`	Aligns text left, center, or right.

Use Cases of TextView

Displaying headings, labels, and instructions.
Showing messages and notifications.
Updating dynamic content (e.g., score in a game).

Conclusion

TextView is an essential UI element in Android for displaying text. It can be styled, modified, and updated dynamically, making it useful for static and dynamic text content.

12) Explain padding in Android with example.

Padding in Android

Padding in Android is the space between the content of a View and its border. It defines how much inner spacing should be kept inside the View before the content starts.

Key Features of Padding

Creates Inner Spacing – Prevents text or images from touching the edges of the View.
Improves Readability – Helps in better UI alignment and appearance.
Can Be Applied Individually – Supports padding for top, bottom, left, and right separately.
Works with All Views – Can be applied to TextView, Button, ImageView, etc.

Types of Padding in Android

android:padding – Applies equal padding to all sides.
android:paddingLeft, android:paddingRight – Sets padding for left and right.
android:paddingTop, android:paddingBottom – Sets padding for top and bottom.
android:paddingHorizontal, android:paddingVertical (API 26+) – Applies padding to left-right or top-bottom together.

Example: Using Padding in Android

1. Define Padding in XML (`activity_main.xml`)


<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">
 
    <TextView
        android:id="@+id/textViewExample"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello, Android!"
        android:textSize="18sp"
        android:background="#CCCCCC"
        android:padding="20dp"/>
 
    <Button
        android:id="@+id/buttonExample"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Click Me"
        android:paddingHorizontal="10dp"
        android:paddingVertical="5dp"/>
</LinearLayout>

2. Modify Padding Programmatically (`MainActivity.java`)


import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
 
public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // Access TextView and set padding dynamically
        TextView textView = findViewById(R.id.textViewExample);
        textView.setPadding(30, 10, 30, 10); // Left, Top, Right, Bottom (in pixels)
    }
}

Explanation

Padding in XML – android:padding="20dp" adds equal spacing inside the TextView.
Custom Padding for Buttons – android:paddingHorizontal="10dp" sets horizontal padding only.
Dynamic Padding in Java – setPadding(30, 10, 30, 10) changes padding at runtime.

Difference Between Padding and Margin

Feature	Padding	Margin
Definition	Space inside the View, between content and border.	Space outside the View, between the View and its parent/sibling Views.
Affects Size?	Increases View size by pushing content inward.	Creates spacing without affecting View size.
Usage	Used for text/image spacing inside a View.	Used for layout spacing between Views.

Use Cases of Padding

Improving UI Design – Adds space to make UI elements readable.
Button & Text Spacing – Ensures text doesn’t touch button edges.
Card & Image Layouts – Provides uniform padding inside cards or images.

Conclusion

Padding in Android improves UI appearance by creating inner spacing inside Views. It helps in better alignment, readability, and visual appeal of UI elements.

13) Explain Button and types of buttons in android.

Button in Android

A Button in Android is a UI component that allows users to perform an action when clicked. It is commonly used for submitting forms, navigating between activities, or triggering events.

Types of Buttons in Android

1. Normal Button (`Button`)

The default button used for general actions.

Example:


<Button
    android:id="@+id/buttonSubmit"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Submit" />

2. Image Button (`ImageButton`)

A button that displays an image instead of text.

Example:


<ImageButton
    android:id="@+id/imageButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/ic_launcher" />

3. Toggle Button (`ToggleButton`)

A button that switches between ON and OFF states.

Example:


<ToggleButton
    android:id="@+id/toggleButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textOn="ON"
    android:textOff="OFF" />

4. Radio Button (`RadioButton`)

Allows users to select one option from a group.

Example:


<RadioGroup android:layout_width="match_parent" android:layout_height="wrap_content">
    <RadioButton android:id="@+id/radio1" android:text="Option 1"/>
    <RadioButton android:id="@+id/radio2" android:text="Option 2"/>
</RadioGroup>

5. CheckBox Button (`CheckBox`)

Allows multiple selections.

Example:


<CheckBox
    android:id="@+id/checkBox1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Accept Terms" />

6. Floating Action Button (`FloatingActionButton`)

A round button that floats above the UI, typically for quick actions.

Example:


<com.google.android.material.floatingactionbutton.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/ic_add"/>

Example: Handling Button Click in Java (`MainActivity.java`)


import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
 
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        // Initialize Button
        Button buttonSubmit = findViewById(R.id.buttonSubmit);
 
        // Handle Button Click
        buttonSubmit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Button Clicked!", Toast.LENGTH_SHORT).show();
            }
        });
    }
}

Conclusion

Android provides different types of buttons for various user interactions, such as normal buttons, image buttons, toggle buttons, and floating action buttons. Buttons improve user experience and navigation within an app.

14) Define the role of XML, JAVA, Manifest and String files in android.

Role of XML, Java, Manifest, and String Files in Android

Android applications are built using multiple components, including XML for UI design, Java (or Kotlin) for logic, Manifest for app configuration, and String files for localization.

1. XML Files (Extensible Markup Language)

Used for defining UI layouts, resources, and configurations.
Located in the res/ directory.

Types of XML Files in Android

XML File	Purpose
`res/layout/activity_main.xml`	Defines the UI layout of an activity.
`res/drawable/`	Stores images and shape resources.
`res/menu/`	Defines menu items for the app.
`res/values/colors.xml`	Stores app color definitions.

Example (activity_main.xml)


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
 
    <TextView
        android:text="Hello, Android!"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</LinearLayout>

2. Java Files

Contain the application logic, event handling, and backend code.
Located in the src/main/java/com.example.myapp/ directory.

Example (MainActivity.java)


import android.os.Bundle;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
 
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        TextView textView = findViewById(R.id.textView);
        textView.setText("Welcome to Android!");
    }
}

3. Android Manifest File (`AndroidManifest.xml`)

Registers components (Activities, Services, Broadcast Receivers).
Declares permissions (e.g., Internet, Camera, Storage).
Specifies app metadata (package name, theme, launcher activity).
Located in the app/src/main/ directory.

Example (`AndroidManifest.xml`)


<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapp">
 
    <uses-permission android:name="android.permission.INTERNET"/>
 
    <application
        android:allowBackup="true"
        android:theme="@style/Theme.MyApp">
 
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
 
    </application>
</manifest>

4. String Resource File (`res/values/strings.xml`)

Stores text values separately to support localization.
Avoids hardcoding text in Java/XML files.

Example (`strings.xml`)


<resources>
    <string name="app_name">My Application</string>
    <string name="welcome_message">Welcome to Android!</string>
</resources>

Using in XML:


<TextView android:text="@string/welcome_message"/>

Using in Java:


textView.setText(getString(R.string.welcome_message));

Conclusion

Component	Purpose
XML Files	Define UI structure, styles, colors, and menus.
Java Files	Handle app logic, user interactions, and functionality.
Manifest File	Configures the app, declares permissions, and registers components.
String Resource File	Stores text separately for localization and easy management.

Each component plays a crucial role in Android development, ensuring structured, maintainable, and scalable applications.

15) Explain the term material design in android with an example.

Material Design in Android

Material Design is a design language developed by Google to create modern, visually appealing, and user-friendly Android applications. It provides a consistent UI experience across different devices using animations, shadows, depth effects, and responsive layouts.

Key Features of Material Design

Elevation & Shadows – Adds depth and layering to UI elements.
Smooth Animations – Uses motion effects for transitions.
Bold Colors & Typography – Promotes clear and readable text.
Responsive UI – Adapts layouts for different screen sizes.
Material Components – Provides pre-built widgets like FloatingActionButton, CardView, AppBar, Bottom Navigation.

Example: Implementing Material Design in Android

1. Add Material Design Dependencies (`build.gradle`)


dependencies {
    implementation 'com.google.android.material:material:1.9.0'
}

2. Use Material Design Components in XML (`activity_main.xml`)


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">
 
    <!-- Material Design Button -->
    <com.google.android.material.button.MaterialButton
        android:id="@+id/materialButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Material Button"
        style="@style/Widget.MaterialComponents.Button.UnelevatedButton"/>
 
    <!-- Floating Action Button -->
    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_add"
        app:backgroundTint="@color/purple_500"/>
 
    <!-- Material CardView -->
    <com.google.android.material.card.MaterialCardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:cardCornerRadius="8dp"
        app:cardElevation="6dp"
        android:padding="16dp"
        android:layout_marginTop="16dp">
 
        <TextView
            android:text="This is a Material CardView"
            android:textSize="16sp"/>
 
    </com.google.android.material.card.MaterialCardView>
 
</LinearLayout>

3. Handle Button Clicks in Java (`MainActivity.java`)


import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.google.android.material.button.MaterialButton;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
 
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        MaterialButton materialButton = findViewById(R.id.materialButton);
        FloatingActionButton fab = findViewById(R.id.fab);
 
        materialButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "Material Button Clicked", Toast.LENGTH_SHORT).show();
            }
        });
 
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "FAB Clicked", Toast.LENGTH_SHORT).show();
            }
        });
    }
}

Conclusion

Material Design improves user experience by adding depth, motion, and responsive UI components. Android provides Material Components like MaterialButton, FloatingActionButton, and CardView, which help in building modern and attractive apps.

16) Differentiate between android themes and style.

Difference Between Android Themes and Styles

Feature	Style	Theme
Definition	A Style is a set of attributes that define the appearance of a single View (Button, TextView, etc.).	A Theme is a collection of styles that apply globally to an entire Activity or Application.
Scope	Applied to individual UI components (e.g., Button, TextView).	Applied to Activities or the entire app.
Usage	Defines colors, text size, padding, margins, etc., for a specific View.	Controls UI appearance, such as AppBar, Status Bar, Backgrounds, and Fonts across the app.
Defined In	`res/values/styles.xml`	`res/values/themes.xml` or `styles.xml`
Applied Using	`style="@style/MyStyle"` in XML for a specific View.	`android:theme="@style/MyTheme"` in `AndroidManifest.xml` for the whole Activity or app.

Example of Style (Applied to a Single View)

styles.xml


<resources>
    <style name="CustomButton">
        <item name="android:background">#6200EE</item>
        <item name="android:textColor">#FFFFFF</item>
        <item name="android:textSize">18sp</item>
        <item name="android:padding">10dp</item>
    </style>
</resources>

Usage in XML Layout (activity_main.xml)


<Button
    android:text="Styled Button"
    style="@style/CustomButton"/>

Example of Theme (Applied to Entire App or Activity)

themes.xml


<resources xmlns:tools="http://schemas.android.com/tools">
    <style name="Theme.MyApp" parent="Theme.MaterialComponents.Light">
        <item name="colorPrimary">#6200EE</item>
        <item name="colorPrimaryVariant">#3700B3</item>
        <item name="colorAccent">#03DAC5</item>
    </style>
</resources>

Apply in AndroidManifest.xml


<application
    android:theme="@style/Theme.MyApp">
</application>

Conclusion

Styles define individual View properties, making UI elements consistent.
Themes apply styles globally, ensuring uniformity across Activities and the entire app.

Both styles and themes enhance UI consistency, flexibility, and maintainability in Android development.

Unit 2

1) What is VIEW? Explain how to create and modify Views?

View in Android

Creating a View

Modifying a View

Conclusion

2) Explain the concept of Datepicker and Timepicker.

DatePicker and TimePicker in Android

1. DatePicker

Example: DatePickerDialog in Java

2. TimePicker

Example: TimePickerDialog in Java

Conclusion

3) Explain the term localization in Android with example.

Localization in Android

Key Features of Localization

Steps for Implementing Localization

Conclusion

4) Explain how to listen Native Broadcast Intents.

Listening to Native Broadcast Intents in Android

Steps to Listen to Native Broadcast Intents

1. Create a BroadcastReceiver Class

2. Register the Receiver in AndroidManifest.xml

3. Register Receiver Dynamically in Activity (Optional)

Common Native Broadcast Intents

Conclusion

5) Explain the concept of Download Manager.

Download Manager in Android

Features of Download Manager

Using Download Manager in Android

1. Add Permission in AndroidManifest.xml

2. Start a File Download

3. Monitor Download Progress

Use Cases of Download Manager

Conclusion

6) Explain Types of Menu Available in Android.

Types of Menu in Android

1. Options Menu

Example: Creating an Options Menu

2. Context Menu

Example: Creating a Context Menu

3. Popup Menu

Example: Creating a Popup Menu

Comparison of Menus

Conclusion

7) Explain spinner in detail with pseudo code.

Spinner in Android

Features of Spinner

Steps to Implement a Spinner

1. Define Spinner in XML Layout (res/layout/activity_main.xml)

2. Create and Set Data in Java (MainActivity.java)

Explanation

Conclusion

8) Write down the pseudo code for Radio button and Checkbox.

Pseudo Code for RadioButton and CheckBox in Android

1. RadioButton in Android

XML Layout for RadioButton (activity_main.xml)

Java Code for RadioButton (MainActivity.java)

2. CheckBox in Android

XML Layout for CheckBox (activity_main.xml)

Java Code for CheckBox (MainActivity.java)

Conclusion

9) Explain Checkbox in Android with example.

CheckBox in Android

Features of CheckBox

Example: Implementing CheckBox in Android

1. Define CheckBoxes in XML (activity_main.xml)

2. Handle CheckBox Selection in Java (MainActivity.java)

Explanation

Use Cases of CheckBox

Conclusion

10) Explain Edit text in Android with example.

EditText in Android

Features of EditText

Example: Implementing EditText in Android

1. Define EditText in XML (activity_main.xml)

2. Handle EditText Input in Java (MainActivity.java)

Explanation

Common Input Types in EditText

Use Cases of EditText

2. Register the Receiver in `AndroidManifest.xml`

1. Add Permission in `AndroidManifest.xml`

1. Define Spinner in XML Layout (`res/layout/activity_main.xml`)

2. Create and Set Data in Java (`MainActivity.java`)

XML Layout for RadioButton (`activity_main.xml`)

Java Code for RadioButton (`MainActivity.java`)

XML Layout for CheckBox (`activity_main.xml`)

Java Code for CheckBox (`MainActivity.java`)

1. Define CheckBoxes in XML (`activity_main.xml`)

2. Handle CheckBox Selection in Java (`MainActivity.java`)

1. Define EditText in XML (`activity_main.xml`)

2. Handle EditText Input in Java (`MainActivity.java`)

1. Define TextView in XML (`activity_main.xml`)

2. Modify TextView Programmatically (`MainActivity.java`)

1. Define Padding in XML (`activity_main.xml`)

2. Modify Padding Programmatically (`MainActivity.java`)

1. Normal Button (`Button`)

2. Image Button (`ImageButton`)

3. Toggle Button (`ToggleButton`)

4. Radio Button (`RadioButton`)

5. CheckBox Button (`CheckBox`)

6. Floating Action Button (`FloatingActionButton`)

Example: Handling Button Click in Java (`MainActivity.java`)

3. Android Manifest File (`AndroidManifest.xml`)

Example (`AndroidManifest.xml`)

4. String Resource File (`res/values/strings.xml`)

Example (`strings.xml`)

1. Add Material Design Dependencies (`build.gradle`)

2. Use Material Design Components in XML (`activity_main.xml`)

3. Handle Button Clicks in Java (`MainActivity.java`)