how to set start Activity in androi studio code example
Example 1: how to open activity in android studio
Intent intent = new Intent(this, DisplayMessageActivity.class);
intent.putExtra(key:,value:);
startActivity(intent);
Example 2: how to change the first activity on android
<activity android:name=".put your started activity name here"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>