//为Button点击事件注册一个监听器
public class Click extends Activity{
   private Button button;
   
   @Override
   ptotected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button = (Button) findViewById(R.id.button);
    button.setOnClickListener(new OnClickListener(){
    @Override
     public void OnClick(View v){
        //点击逻辑
     }
   });
   }  
} 

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  button = (Button) findViewById(R.id.button);
  editText = (EditText) findViewById(R.id.edit);
  button.setOnClickListener(new View.OnClickListener(){
   @Override
   public void onClick(View view) {
    String inputText = editText.getText().toString();
    Toast.makeText(MainActivity.this, inputText,
      Toast.LENGTH_SHORT).show();
   }
  });
 }

@Override
 protected void onCreate(Bundle savedInstanceState){
   super.onCreate(savedInstanceState);
  setContentView(R.layout.image);
  button = (Button) findViewById(R.id.button_img);
  imageView = (ImageView) findViewById(R.id.image);
  button.setOnClickListener( new View.OnClickListener(){
   @Override
   public void onClick(View view){
     imageView.setImageResource(R.drawable.two);
   }
  });
 }
//通过调用 ImageView 的 setImageResource()方法将显示的图片改成two

public class ProgressBar extends Activity {
 private Button button;
 private ProgressBar progressBar;

 @Override
 protected void onCreate(Bundle savedInstanceState){
  super.onCreate(savedInstanceState);
  setContentView(R.layout.progressbar);
  button = (Button) findViewById(R.id.button_progress);
 /*  progressBar = (ProgressBar) findViewById(R.id.progress);*/
  button.setOnClickListener( new View.OnClickListener(){
   @Override
   public void onClick(View view){

   }
  });
 }
}