Listening and processing instances of the Back key in Android applications
- 2020-05-17 06:23:17
- OfStack
MainActivity is as follows:
main. xml as follows:
package cn.testnbackpressed;
import android.os.Bundle;
import android.view.KeyEvent;
import android.app.Activity;
/**
* Demo describe :
* To deal with Back Press the event
*
* Matters needing attention :
* There are two ways 1 The use
*/
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
/**
* Listening to the Back Press the event , methods 1:
* Pay attention to :
* super.onBackPressed() Will automatically call finish() methods , Shut down
* The current Activity.
* If you want to block Back The keyboard , Just comment the line of code
*/
@Override
public void onBackPressed() {
super.onBackPressed();
System.out.println(" Press the back key onBackPressed()");
}
/**
* Listening to the Back Press the event , methods 2:
* Pay attention to :
* Return value representation : Whether the event can be fully handled
* Return here false, So it will continue to spread the story .
* The return value here is project-specific .
*/
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK)) {
System.out.println(" Press the back key onKeyDown()");
return false;
}else {
return super.onKeyDown(keyCode, event);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
System.out.println(" perform onDestroy()");
}
}
main. xml as follows:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" for Back Two ways of dealing with keys "
android:layout_centerInParent="true"
android:textSize="20sp"
/>
</RelativeLayout>