I am assuming that by “packages” you mean applications.
We have:
– ApplicationA with FirstActivity
– ApplicationB with SecondActivity
If, in the ApplicationB’s AndroidManifest.xml file, in the declaration of SecondActivity you add an intent filter such as:
<activity android:name=".SecondActivity">
<intent-filter>
<action android:name="applicationB.intent.action.Launch" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
You can create an Intent to launch this SecondActivity from the FirstActivity with:
Intent intent = new Intent("applicationB.intent.action.Launch");
startActivity(intent);
What this all means is:
- The SecondActivity has a filter for the intent action of “applicationB.intent.action.Launch”
- When you create an intent with that action and call ‘startActivity’ the system will find the activity (if any) that responds to it
The documentation for this is at: https://developer.android.com/reference/android/content/Intent.html