注册事件

package net.learn2develop.UIActivity;import android.app.Activity;import android.os.Bundle;import android.view.KeyEvent;import android.view.View;import android.widget.Toast;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity{/**Calledwhentheactivityisfirstcreated.*/@Overridepublic void onCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);//---the two buttons are wired to the same event handler---Button btn1 = (Button)findViewById(R.id.btn1);btn1.setOnClickListener(btnListener);Button btn2 = (Button)findViewById(R.id.btn2);btn2.setOnClickListener(btnListener);}//---create an anonymous class to act as a button click listener---private OnClickListener btnListener= new OnClickListener(){public void onClick(View v){Toast.makeText(getBaseContext(),((Button) v).getText() + “ was clicked”,Toast.LENGTH_LONG).show();}};@Overridepublic boolean onKeyDown(intkeyCode,KeyEventevent){switch(keyCode){//...//...}returnfalse;}}这是定义一个匿名类来注册事件。import android.widget.EditText;public class MainActivity extends Activity{Listening for Ui notifications ❘ 121/**Calledwhentheactivityisfirstcreated.*/@Overridepublic void onCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);//---thetwobuttonsarewiredtothesameeventhandler---Buttonbtn1=(Button)findViewById(R.id.btn1);btn1.setOnClickListener(btnListener);Buttonbtn2=(Button)findViewById(R.id.btn2);btn2.setOnClickListener(btnListener);EditText txt1 = (EditText)findViewById(R.id.txt1);//---create an anonymous inner class to act as an onfocus listener---txt1.setOnFocusChangeListener(newView.OnFocusChangeListener(){@Overridepublic void onFocusChange(View v, booleanhasFocus) {Toast.makeText(getBaseContext(),((EditText) v).getId() + “ has focus - “+ hasFocus,Toast.LENGTH_LONG).show();}});}这是一个匿名内部类。
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