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Intents

An Intent is a messaging object used to request an action from another app component (Activity, Service, BroadcastReceiver). They facilitate communication between different parts of your app or even between different apps entirely.

Types of Intents​

1. Explicit Intents​

Used to start a specific component within your own application. You provide the exact class name.

val intent = Intent(this, DetailActivity::class.java)
intent.putExtra("ITEM_ID", 123)
startActivity(intent)

2. Implicit Intents​

Used to ask the system to find an app that can handle a generic action (like taking a photo, opening a URL, or sharing text). You do not specify the exact component name.

val intent = Intent(Intent.ACTION_SEND).apply {
    type = "text/plain"
    putExtra(Intent.EXTRA_TEXT, "Check out this app!")
}
startActivity(Intent.createChooser(intent, "Share via..."))

Intent Filters​

For your app to respond to implicit intents from other apps, you declare <intent-filter> elements within the component's declaration in the AndroidManifest.xml.

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

Note: The android:exported="true" flag is required in modern Android (API 31+) if an intent filter is present.

PendingIntent​

A PendingIntent is a wrapper around a regular intent that grants another application (like the NotificationManager, AlarmManager, or a Home Screen Widget) the right to execute the wrapped intent as if it were executed by your own app, with your app's permissions.

Interview Questions​

Q: What are the primary uses of PendingIntent? Answer: PendingIntent is primarily used for handling taps on Notifications, scheduling alarms via AlarmManager, or interacting with App Widgets. It allows external applications to execute predefined actions on behalf of your app.

Q: Explain Intent Flags. Answer: Flags dynamically alter the behavior of how an intent is handled or which task an Activity belongs to. For example, FLAG_ACTIVITY_CLEAR_TOP clears all activities on top of the target activity if it is already in the back stack. FLAG_ACTIVITY_NEW_TASK starts a new task stack (often needed when starting an Activity from outside a standard Activity context, like from a Service).