Android Intents

An abstract description of an operation to be performed. It acts as a bridge between Android app components.

Types of Intents

Explicit Intent
- Used for navigation within the same application.
- You know the exact class name of the component to start.
Implicit Intent
- Used for communication between different applications.
- You specify an action, and Android selects the best app to handle it.

2. Explicit Intents (Internal Navigation)

A. Sender Side (Starting an Activity)

Basic Navigation

Intent intent = new Intent(MainActivity.this, SecondActivity.class);
startActivity(intent);

Passing Data (Sender)

Data is passed using key–value pairs via putExtra().

Intent intent = new Intent(MainActivity.this, SecondActivity.class);

// Primitive Data Types
intent.putExtra("USER_NAME", "Ali");
intent.putExtra("USER_AGE", 25);
intent.putExtra("IS_VERIFIED", true);

// Bundle (Grouped Data)
Bundle bundle = new Bundle();
bundle.putDouble("GPA", 3.8);
intent.putExtras(bundle);

startActivity(intent);

B. Receiver Side (Retrieving Data)

Place this code inside onCreate() of the target Activity.

Intent intent = getIntent();

// Primitive Data
String name = intent.getStringExtra("USER_NAME");
int age = intent.getIntExtra("USER_AGE", 0);
boolean verified = intent.getBooleanExtra("IS_VERIFIED", false);

// Bundle Data
Bundle args = intent.getExtras();
if (args != null) {
    double gpa = args.getDouble("GPA");
}

3. Implicit Intents (Common Actions)

A. Location (Maps)

Action: Intent.ACTION_VIEW

Style 1: Specific Coordinates

Uri location = Uri.parse("geo:37.7749,-122.4194");
Intent mapIntent = new Intent(Intent.ACTION_VIEW, location);
startActivity(mapIntent);

Style 2: Search Address

Uri address = Uri.parse("geo:0,0?q=1600+Amphitheatre+Parkway");
Intent mapIntent = new Intent(Intent.ACTION_VIEW, address);
startActivity(mapIntent);

B. Web Browser

Action: Intent.ACTION_VIEW

Uri webpage = Uri.parse("https://www.google.com");
Intent webIntent = new Intent(Intent.ACTION_VIEW, webpage);
startActivity(webIntent);

C. Phone Dialer

Style 1: Open Dial Pad (Safe)

Action: Intent.ACTION_DIAL

Uri number = Uri.parse("tel:03001234567");
Intent dialIntent = new Intent(Intent.ACTION_DIAL, number);
startActivity(dialIntent);

Style 2: Direct Call (Permission Required)

Action: Intent.ACTION_CALL

Manifest Permission

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

Uri number = Uri.parse("tel:03001234567");
Intent callIntent = new Intent(Intent.ACTION_CALL, number);
startActivity(callIntent);

⚠️ App crashes if runtime permission is missing.

4. Advanced Implicit Scenarios

A. Sharing Content (Share Sheet)

Action: Intent.ACTION_SEND

Intent shareIntent = new Intent(Intent.ACTION_SEND);
shareIntent.setType("text/plain");

shareIntent.putExtra(Intent.EXTRA_SUBJECT, "Email Subject");
shareIntent.putExtra(Intent.EXTRA_TEXT, "This is the body text.");

// Force chooser dialog
startActivity(Intent.createChooser(shareIntent, "Share via"));

MIME Type Filtering

shareIntent.setType("image/jpeg"); // Images
shareIntent.setType("video/*");    // Videos

Multiple MIME Types (Image OR PDF)

Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("*/*");

String[] mimeTypes = {"image/*", "application/pdf"};
intent.putExtra(Intent.EXTRA_MIME_TYPES, mimeTypes);

filePickerLauncher.launch(intent);

EXTRA Attributes Summary

Attribute	Primary Use	Email	WhatsApp
EXTRA_SUBJECT	Context / Title	Subject line	Ignored
EXTRA_TEXT	Main content	Body	Message
EXTRA_EMAIL	Recipient	"To" field	Ignored
EXTRA_STREAM	Attachments	File attachment	Preview

B. Receiving Implicit Intents (Share Receiver)

AndroidManifest.xml

<activity android:name=".ShareReceiverActivity">
    <intent-filter>
        <action android:name="android.intent.action.SEND" />
        <category android:name="android.intent.category.DEFAULT" />
        <data android:mimeType="text/plain" />
    </intent-filter>
</activity>

Java (ShareReceiverActivity)

Intent intent = getIntent();

if (Intent.ACTION_SEND.equals(intent.getAction())
        && "text/plain".equals(intent.getType())) {

    String sharedText = intent.getStringExtra(Intent.EXTRA_TEXT);
}

5. Activity Result Launcher (Modern API)

Launcher Setup

ActivityResultLauncher filePickerLauncher = registerForActivityResult( new ActivityResultContracts.StartActivityForResult(), new ActivityResultCallback() { @Override public void onActivityResult(ActivityResult result) { if (result.getResultCode() == Activity.RESULT_OK) { Intent data = result.getData(); if (data != null) { Uri fileUri = data.getData(); // Handle file here... } } } } );

Launcher Setup (Lambda)

ActivityResultLauncher<Intent> filePickerLauncher =
        registerForActivityResult(
                new ActivityResultContracts.StartActivityForResult(),
                result -> {
                    if (result.getResultCode() == Activity.RESULT_OK) {
                        Intent data = result.getData();
                        if (data != null) {
                            Uri fileUri = data.getData();
                        }
                    }
                }
        );

Launch Image Picker

public void uploadImage() {
    Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
    intent.setType("image/*");
    filePickerLauncher.launch(intent);
}

Handling Image & PDF Selection

1. The Launcher (Receiver)

This code sits at the top of your Activity. It waits for the user to pick a file.

// Assumed UI elements
ImageView myImageView = findViewById(R.id.imgPreview);
TextView myPdfTextView = findViewById(R.id.pdfNamePreview);

ActivityResultLauncher<Intent> filePickerLauncher = registerForActivityResult(
    new ActivityResultContracts.StartActivityForResult(),
    result -> {
        if (result.getResultCode() == Activity.RESULT_OK) {
            Intent data = result.getData();
            if (data != null) {
                // 1. Get the File Path (Uri)
                Uri selectedUri = data.getData();
                
                // 2. Check: Is it Image or PDF?
                String type = getContentResolver().getType(selectedUri);
                
                if (type != null) {
                    if (type.startsWith("image/")) {
                        // HANDLE IMAGE
                        // Simplest way to show image from Uri
                        myImageView.setImageURI(selectedUri);
                        
                        // Hide PDF text
                        myPdfTextView.setVisibility(View.GONE);
                        myImageView.setVisibility(View.VISIBLE);
                        
                    } else if (type.equals("application/pdf")) {
                        // HANDLE PDF
                        // We cannot "show" a PDF in an ImageView. 
                        // Instead, we show an icon or the file name.
                        myPdfTextView.setText("PDF Selected: " + selectedUri.getLastPathSegment());
                        
                        // Hide Image view
                        myImageView.setVisibility(View.GONE);
                        myPdfTextView.setVisibility(View.VISIBLE);
                    }
                }
            }
        }
    }
);

#### Launch Image or PDF Picker

```java
public void uploadMixed() {
    Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
    intent.setType("*/*");

    String[] mimeTypes = {"image/*", "application/pdf"};
    intent.putExtra(Intent.EXTRA_MIME_TYPES, mimeTypes);

    filePickerLauncher.launch(intent);
}

B. Explicit Usage (Returning Result from Activity)

MainActivity (Sender)

ActivityResultLauncher<Intent> myActivityLauncher =
        registerForActivityResult(
                new ActivityResultContracts.StartActivityForResult(),
                result -> {
                    if (result.getResultCode() == Activity.RESULT_OK) {
                        Intent data = result.getData();
                        String message = data.getStringExtra("RESULT_KEY");
                    }
                }
        );

public void openActivityB() {
    Intent intent = new Intent(MainActivity.this, SecondActivity.class);
    myActivityLauncher.launch(intent);
}

SecondActivity (Receiver)

Intent resultIntent = new Intent();
resultIntent.putExtra("RESULT_KEY", "Task Completed Successfully");

setResult(Activity.RESULT_OK, resultIntent);
finish();

6. Result Codes Explained

When an Activity returns data, it sends a status code (resultCode) to tell the parent what happened.

Code	Value	Meaning
RESULT_OK	`-1`	The operation succeeded. The user picked a file, took a photo, or submitted data.
RESULT_CANCELED	`0`	The user backed out. They pressed the "Back" button or closed the picker without selecting anything.
RESULT_FIRST_USER	`1`	Start of custom user-defined codes. You can use this if you want to define specific custom results (e.g., `EDIT_COMPLETED = 1`, `DELETE_COMPLETED = 2`).

Usage Example:

if (result.getResultCode() == Activity.RESULT_CANCELED) {
    // User pressed back without selecting anything
    Toast.makeText(this, "Selection Cancelled", Toast.LENGTH_SHORT).show();
}

7. Runtime Permissions (The Modern Way)

This uses ActivityResultLauncher with the RequestPermission contract. It returns a Boolean (True/False) instead of an Intent.

A. Setup (Manifest)

Crucial: You must always declare the permission in AndroidManifest.xml first.

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

Common Android Permissions

Permission Name	Usage
`INTERNET`	Allows the app to access the Internet (APIs, Web).
`ACCESS_NETWORK_STATE`	Checks if the device is connected to WiFi or Mobile Data.
`READ_EXTERNAL_STORAGE`	accessing files on shared storage (Android 12 and below).
`READ_MEDIA_IMAGES`	Accessing photos/images only (Android 13+).
`READ_MEDIA_VIDEO`	Accessing video files only (Android 13+).
`CAMERA`	Accessing the camera sensor for photos or video.
`RECORD_AUDIO`	Accessing the microphone for voice notes or calls.
`ACCESS_FINE_LOCATION`	Precise location using GPS satellites.
`ACCESS_COARSE_LOCATION`	Approximate location using WiFi/Cell towers.
`READ_CONTACTS`	Reading user's address book data.
`CALL_PHONE`	Initiating a phone call directly without user confirmation.
`SEND_SMS`	Sending text messages in the background.
`READ_SMS`	Reading messages from the user's Inbox.
`BLUETOOTH_CONNECT`	Connecting to paired Bluetooth devices (Headphones, etc.).

B. The Launcher (Receiver)

Define this variable at the top of your class (outside methods).

private final ActivityResultLauncher<String> requestPermissionLauncher =
    registerForActivityResult(new ActivityResultContracts.RequestPermission(),
        new ActivityResultCallback<Boolean>() {
            @Override
            public void onActivityResult(Boolean isGranted) {
                if (isGranted) {
                    startRecording();
                } else {
                    handleDenial();
                }
            }
        });

C. The Trigger Logic (Asking User)

Do not launch immediately. Check if you already have it first.

public void onRecordButtonClick() {
    // 1. Check if permission is ALREADY granted
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO) 
            == PackageManager.PERMISSION_GRANTED) {
        
        // We have it -> Go!
        startRecording();
        
    } else {
        // We don't have it -> Ask the user
        // This triggers the System Dialog (or auto-denies if blocked)
        requestPermissionLauncher.launch(Manifest.permission.RECORD_AUDIO);
    }
}

8. Handling "Don't Ask Again" (Settings Redirect)

If the user selects "Don't Ask Again" (or denies twice on modern Android), the system blocks the popup. You must detect this and send them to Settings.

Logic Flow:

Launcher returns false.
check shouldShowRequestPermissionRationale().

True: User denied normally. Show a Toast.
False: User is blocked ("Don't Ask Again"). Show Dialog to open Settings.

Implementation:

private void handleDenial() {
    // Check if the system blocked the popup
    if (shouldShowRequestPermissionRationale(Manifest.permission.RECORD_AUDIO)) {
        // Case 1: Normal Denial
        Toast.makeText(this, "Permission is needed to record audio.", Toast.LENGTH_SHORT).show();
    } else {
        // Case 2: "Don't Ask Again" Checked (Permanent Denial)
        showSettingsDialog();
    }
}

private void showSettingsDialog() {
    new AlertDialog.Builder(this)
        .setTitle("Permission Required")
        .setMessage("You have permanently disabled this feature. Please enable it in Settings.")
        .setPositiveButton("Go to Settings", (dialog, which) -> {
            // Intent to open App Settings Page
            Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
            Uri uri = Uri.fromParts("package", getPackageName(), null);
            intent.setData(uri);
            startActivity(intent);
        })
        .setNegativeButton("Cancel", null)
        .show();
}

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