edittext登录界面，用户名修改，密码自动删除效果

/**

 * 登录界面

 */

public class Login extends Activity implements OnClickListener {
private Button btn_login;
private EditText et_username;
private EditText et_userpwd;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.login);
btn_login = (Button) findViewById(R.id.btn_login);
et_username = (EditText) findViewById(R.id.et_username);
et_username.addTextChangedListener(textWatcher); 
et_userpwd = (EditText) findViewById(R.id.et_userpwd);

}
private TextWatcher textWatcher = new TextWatcher() {  
@Override
public void afterTextChanged(Editable s) {

}
       @Override 
       public void beforeTextChanged(CharSequence s, int start, int count,  
               int after) {  
       
et_userpwd.setText("");  //输入的文字发生变化，设置密码输入为空
       }  
 
        @Override    
       public void onTextChanged(CharSequence s, int start, int before,     
               int count) {     
                             
       }                    
   };  

}