演示事件处理的三种方式（以SayHello为例）

1.MainActivity1

public class MainActivity extends Activity {  private Button clickButton;     private EditText nameText;     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);        /* ImageView imageView=new ImageView(this);         imageView.setImageResource(R.drawable.bg);         setContentView(imageView);*/         setContentView(R.layout.activity_main);         initialComponents();         //绑定事件源和事件处理者         clickButton.setOnClickListener(new ClickHandler());             }     //编写有能力处理按钮点击事件类     private  class ClickHandler implements OnClickListener{

  @Override   public void onClick(View v) {    String name=nameText.getText().toString();    Toast.makeText(MainActivity.this, "你好"+name, Toast.LENGTH_LONG).show();   }           }         private void initialComponents(){      clickButton=(Button) this.findViewById(R.id.clickButton);         nameText=(EditText) findViewById(R.id.name);     }     @Override     public boolean onCreateOptionsMenu(Menu menu) {         getMenuInflater().inflate(R.menu.activity_main, menu);         return true;     }

    }

2.MainActivity2

public class MainActivity extends Activity {  private Button clickButton;     private EditText nameText;     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);        /* ImageView imageView=new ImageView(this);         imageView.setImageResource(R.drawable.bg);         setContentView(imageView);*/         setContentView(R.layout.activity_main);         initialComponents();         //绑定事件源和事件处理者         //clickButton.setOnClickListener(new ClickHandler());匿名对象         clickButton.setOnClickListener(new OnClickListener(){

   @Override    public void onClick(View v) {     String name=nameText.getText().toString();     Toast.makeText(MainActivity.this, "你好"+name, Toast.LENGTH_LONG).show();    }                   });             }         private void initialComponents(){      clickButton=(Button) this.findViewById(R.id.clickButton);         nameText=(EditText) findViewById(R.id.name);     }     @Override     public boolean onCreateOptionsMenu(Menu menu) {         getMenuInflater().inflate(R.menu.activity_main, menu);         return true;     }

    }[/code]3.MainActivity2

public class MainActivity extends Activity {     private EditText nameText;     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);         initialComponents();     }         public void clickHandler(View view){      String name=nameText.getText().toString();   Toast.makeText(MainActivity.this, "你好"+name, Toast.LENGTH_LONG).show();     }     private void initialComponents(){         nameText=(EditText) findViewById(R.id.name);     }     @Override     public boolean onCreateOptionsMenu(Menu menu) {         getMenuInflater().inflate(R.menu.activity_main, menu);         return true;     }

    }