Understanding intents in Android

Intents are how Android components—or apps—tell each other to do something, like open a screen, send data, or start a system action. It is more of like sending a letter with the intent mentioned, and Android delivers it where it's supposed to go (opening a camera, navigating around system).

There are two types of intents mainly. Explicit Intents & Implicit intents

explicit intents : starts a specific component (own activity mainly)

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

implicit intents : invokes system or third-party actions

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setData(Uri.parse("https://openai.com"));
startActivity(intent);

#Intent filters

Defined in AndroidManifest.xml to allow other apps to call specific components intent filter consists of 3 parts :

• action - type of intent? (like "android.intent.action.VIEW")
• category - additional info telling how the component is supposed to be used ("android.intent.category.DEFAULT")
• data - type of data to accept (mimeType="text/plain" or scheme="http")

some common use cases are sharing text ACTION_SEND, picking image ACTION_PICK, open map ACTION_VIEW.

#Passing data

When using an Intent to start another Activity or Service, you can attach extra data to it using key-value pairs.

attaching data to the intent (sender)

• putExtra(key, value) for simple types
• putExtras(Bundle) for multiple key-value paris on a single instance

Intent intent = new Intent(this, ProfileActivity.class);
intent.putExtra("username", "goober");
intent.putExtra("age", 51);
startActivity(intent);

this intent now carries "username" = "goober" and "age" = 51

retrieving the data (receiver)

• inside ProfileActivity

String username = getIntent().getStringExtra("username");
int age = getIntent().getIntExtra("age", -1); // -1 = default if not found

#Debugging intents

• use adb shell am start to trigger intents with manual ----------
• logcat is your saviour use the filters :p

#Conclusion

Passing data with Intent extras is like slipping notes between Android components — just don’t forget the key, or your app’s memory might ghost you.