Android onClick按钮单击事件的四种常用写法

<EditText 
 android:layout_width="match_parent" 
 android:layout_height="wrap_content" 
 android:inputType="phone" 
 android:ems="10" 
 android:id="@+id/et_number" 
 android:layout_alignParentTop="true" 
 android:layout_alignParentLeft="true" 
 android:layout_alignParentStart="true" /> 
<Button 
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:text="@string/dial_number" 
 android:id="@+id/bt_dial" 
 android:layout_below="@id/et_number" 
 android:layout_alignRight="@id/et_number" 
 android:layout_alignEnd="@id/et_number" /> 

protected void onCreate(Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
 setContentView(R.layout.activity_main); 
 Button bt_dial = (Button) findViewById(R.id.bt_dial); 
 bt_dial.setOnClickListener(new View.OnClickListener() { 
  @Override 
  public void onClick(View view) { 
   dialPhone(); 
  } 
 }); 
} 

protected void onCreate(Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
  et_number = (EditText) MainActivity.this.findViewById(R.id.et_number); 
  Button bt_dial = (Button) findViewById(R.id.bt_dial); 
  bt_dial.setOnClickListener(new MyListener()); 
 } 
 private class MyListener implements View.OnClickListener { 
 @Override 
 public void onClick(View view) { 
  dialPhone(); 
 } 
} 

public class MainActivity extends Activity implements View.OnClickListener { 
 EditText et_number; 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
  et_number = (EditText) MainActivity.this.findViewById(R.id.et_number); 
 Button bt_dial = (Button) findViewById(R.id.bt_dial); 
  bt_dial.setOnClickListener(this); 
 } 
 public void onClick(View view) { 
  switch (view.getId()){ 
   case R.id.bt_dial: 
    dialPhone(); 
    break; 
   default: 
    break; 
  } 
 } 
} 

<Button 
  android:onClick="dialPhoneMethod" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:text="@string/dial_number" 
  android:id="@+id/bt_dial" 
  android:layout_below="@id/et_number" 
  android:layout_alignRight="@id/et_number" 
  android:layout_alignEnd="@id/et_number" /> 
public void dialPhoneMethod(View view){ 
 dialPhone(); 
} 
private void dialPhone() { 
 String number = et_number.getText().toString().trim(); 
 if (TextUtils.isEmpty(number)){ 
  Toast.makeText(this, "电话号码不能为空", Toast.LENGTH_LONG).show(); 
  return; 
 } 
 Intent intent = new Intent(); 
 intent.setAction(Intent.ACTION_CALL); 
 intent.setData(Uri.parse("tel:" + number)); 
 startActivity(intent); 
}