Android Physics keystroke finishing and instance code _android

Let's look at a piece of code and then explain.

Import android.app.Activity;
 Import Android.os.Bundle;
 Import Android.util.Log;
 Import android.view.KeyEvent;
 
 Import Android.widget.Toast;
     public class Mainactivity extends activity {@Override protected void onCreate (Bundle savedinstancestate) {
     Super.oncreate (savedinstancestate);
   Setcontentview (R.layout.activity_main); //We are dealing with physical key events, the callback methods provided are onkeyup (), OnKeyDown (), and onkeylongpress (), such as volume keys, return keys @Override public boolean onKeyDown (in
     T KeyCode, KeyEvent event) {if (keycode = = Keyevent.keycode_back) {log.e ("TAG", "This is the monitor keyboard operation, press the back Key");
   Return Super.onkeydown (KeyCode, event);
       @Override public boolean onKeyUp (int keycode, keyevent event) {if (keycode = = keyevent.keycode_volume_up) {
     LOG.E ("TAG", "Volume add Key");
   Return Super.onkeyup (KeyCode, event); 
   In//activity, we can rewrite the onbackpressed () method to handle the return key, such as two times the key to exit///First press, record Event//second pressed event minus the first pressed time less than 2s to exit, otherwise the current time will be assigned to the first event
   
   Long StartTime; @OvErride public void onbackpressed () {LOG.E ("TAG", "Monitor back Key"); if (System.currenttimemillis ()-starttime<2000) {super.onbackpressed ()//Releasing resources, this can also be directly finish (), but the invocation of the parent class's release is more thorough}e
       lse{//Record current time StartTime = System.currenttimemillis ();
     Toast.maketext (This, "press the back key again", Toast.length_short). Show ();
 
 }
   }
   
 }

Some common physical buttons

Power Key Keycode_power

Back Key Keycode_back

Menu Key Keycode_menu

Home Key Keycode_home

Camera Key Keycode_camera

Volume key KEYCODE_VOLUME_UP/KEYCODE_VOLUME_DOWM

Search Key Keycode_search

Directional key Keycode_dpad_center

Keycode_dpad_up

Keycode_dpad_down

Keycode_dpad_left

Keycode_dpad_right

Keyboard keys Keycode_0...keycode_9

Keycode_a ..... Keycode_z

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