Learn android from scratch (android event handling method. 24 .)

Learn android from scratch (android event handling method. 24 .)

There are a variety of events in android, each of which has its own Processing Mechanism

For example

1	Click Event	View. OnClickListener	Public abstract void onClick (View v)	Triggered when a component is clicked
2	Click Event	View. OnLongClickListener	Public abstract boolean onLongClick (View v)	Triggered when long-pressed Components
3	Keyboard Events	View. OnKeyListener	Public abstract boolean onKey (View v, int keyCode, KeyEvent event)	Handle Keyboard Events
4	Focus event	View. OnFocusChangeListener	Public abstract void onFocusChange (View v, boolean hasFocus)	Triggered when the focus changes
5	Touch event	View. OnTouchListener	Public abstract boolean onTouch (View v, MotionEvent event)	Generate touch events
6	Create context menu	View. OnCreateContextMenuListener	Public abstract void onCreateContextMenu (ContextMenu menu, View v, ContextMenu. ContextMenuInfo menuInfo)	Triggered when the context menu is created

Listener Method

1	Public void setOnClickListener (View. OnClickListener l)	Normal	Register a click event
2	Public void setOnLongClickListener (View. OnLongClickListener l)	Normal	Registration duration event
3	Public void setOnKeyListener (View. OnKeyListener l)	Normal	Register Keyboard Events
4	Public void setOnFocusChangeListener (View. OnFocusChangeListener l)	Normal	Registration focus change event
5	Public void setOnTouchListener (View. OnTouchListener l)	Normal	Register touch events
6	Public void setOnCreateContextMenuListener (View. OnCreateContextMenuListener l)	Normal	Register context menu events

The following uses the Onclick single-host event as an example to describe three methods of event processing in android.

1. Internal handling events

2. Anonymous internal event handling

3. Data Source Processing Event

Example:

XML file

JAVA files

Package com. example. actionoperator; import android. app. activity; import android. OS. bundle; import android. view. view; import android. view. view. onClickListener; import android. widget. button; import android. widget. toast; public class MainActivity extends Activity {public Button button1, button2, button3; // get the response object ButtonOnClickListener click = new ButtonOnClickListener (); @ jsonvoid onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); super. setContentView (R. layout. activity_main); button1 = (Button) this. findViewById (R. id. button1); button2 = (Button) this. findViewById (R. id. button2); button3 = (Button) this. findViewById (R. id. button3); // use an internal class to process button1.setOnClickListener (new MyListener (); // use an anonymous internal class to process button2.setOnClickListener (new OnClickListener () {@ Overridepublic void onClick (View arg0) {// TODO Auto-generated method stubToast. makeText (MainActivity. this, "listener processing for methods of anonymous internal classes", 2 ). show () ;}}); // use the data source method for processing. It can be said that all standalone events are registered on this click to process button3.setOnClickListener (click );} class ButtonOnClickListener implements OnClickListener {public void onClick (View v) {// The reader can set the switch case statement here to determine the ID of the passed parameter to implement the same method for processing multiple events if (v = button3) {Toast. makeText (MainActivity. this, "using data sources for method listening", 2 ). show () ;}} class MyListener implements OnClickListener {@ Overridepublic void onClick (View view) {// TODO Auto-generated method stubToast. makeText (MainActivity. this, "internal class method implementation method listener processing", 2 ). show ();}}}

Final Effect

All event handling methods are basically three of the above, and we hope that readers can master them carefully.

Next forecast:

Dialog box component