Android buttons: Four event types

Android buttons: Four event types

In the course of studying Android, whether watching videos or blogs, I found that everyone has different preferences in coding, obviously, it is different in writing controls to respond to events. So I want to summarize these writing methods and compare the advantages and disadvantages of different writing methods. I hope that I can flexibly select the encoding method.

 

Xml file

 1     <Button 2         android:id="@+id/button1" 3         android:layout_width="wrap_content" 4         android:layout_height="wrap_content" 5         android:text="Button1" /> 6  7     <Button 8         android:id="@+id/button2" 9         android:layout_width="wrap_content"10         android:layout_height="wrap_content"11         android:text="Button2" />

 

Four methods:

• Anonymous internal class

 1 public class TestButtonActivity extends Activity { 2  3     Button btn1, btn2; 4     Toast tst; 5  6     @Override 7     protected void onCreate(Bundle savedInstanceState) { 8         super.onCreate(savedInstanceState); 9         setContentView(R.layout.activity_test_button);10 11         btn1 = (Button) findViewById(R.id.button1);12         btn2 = (Button) findViewById(R.id.button2);13 14         btn1.setOnClickListener(new OnClickListener() {15 16             @Override17             public void onClick(View v) {18                 // TODO Auto-generated method stub19                 Toast tst = Toast.makeText(TestButtonActivity.this, "111111111", Toast.LENGTH_SHORT);20                 tst.show();21 22             }23         });24 25         btn2.setOnClickListener(new OnClickListener() {26 27             @Override28             public void onClick(View v) {29                 // TODO Auto-generated method stub30                 Toast tst = Toast.makeText(TestButtonActivity.this, "222222222", Toast.LENGTH_SHORT);31                 tst.show();32             }33         });34     }35 36 }

 

• Custom click event listening class

 1 public class TestButtonActivity extends Activity { 2  3     Button btn1, btn2; 4     Toast tst; 5  6     class MyClickListener implements OnClickListener { 7  8         @Override 9         public void onClick(View v) {10             // TODO Auto-generated method stub11             switch (v.getId()) {12             case R.id.button1:13                 tst = Toast.makeText(TestButtonActivity.this, "111111111", Toast.LENGTH_SHORT);14                 tst.show();15                 break;16             case R.id.button2:17                 tst = Toast.makeText(TestButtonActivity.this, "222222222", Toast.LENGTH_SHORT);18                 tst.show();19                 break;20             default:21                 break;22             }23         }24 25     }26 27     @Override28     protected void onCreate(Bundle savedInstanceState) {29         super.onCreate(savedInstanceState);30         setContentView(R.layout.activity_test_button);31 32         btn1 = (Button) findViewById(R.id.button1);33         btn2 = (Button) findViewById(R.id.button2);34 35         btn1.setOnClickListener(new MyClickListener());36         btn2.setOnClickListener(new MyClickListener());37     }38 39 }

 

• The Activity inherits View. OnClickListener, and The OnClick (View view) method is implemented by the Activity. In The OnClick (View view) method, switch-case is used to process the buttons represented by different IDs.

 1 public class TestButtonActivity extends Activity implements OnClickListener { 2  3     Button btn1, btn2; 4     Toast tst; 5  6     @Override 7     protected void onCreate(Bundle savedInstanceState) { 8         super.onCreate(savedInstanceState); 9         setContentView(R.layout.activity_test_button);10 11         btn1 = (Button) findViewById(R.id.button1);12         btn2 = (Button) findViewById(R.id.button2);13 14         btn1.setOnClickListener(this);15         btn2.setOnClickListener(this);16     }17 18     @Override19     public void onClick(View v) {20         // TODO Auto-generated method stub21         switch (v.getId()) {22         case R.id.button1:23             tst = Toast.makeText(this, "111111111", Toast.LENGTH_SHORT);24             tst.show();25             break;26         case R.id.button2:27             tst = Toast.makeText(this, "222222222", Toast.LENGTH_SHORT);28             tst.show();29             break;30         default:31             break;32         }33     }34 }

 

• The last one is a method I saw today. In the XML file, "The onClick attribute of the specified button is displayed. In this way, when you click a button, the click () in the corresponding Activity is called Using Reflection () method "[NOTE 1]

 1     <Button 2         android:id="@+id/button1" 3         android:layout_width="wrap_content" 4         android:layout_height="wrap_content" 5         android:onClick="onClick" 6         android:text="Button1" /> 7  8     <Button 9         android:id="@+id/button2"10         android:layout_width="wrap_content"11         android:layout_height="wrap_content"12         android:onClick="onClick"13         android:text="Button2" />

Here, the message indicating the onClick attribute is displayed when you press Alt +/when you enter android: onClick = ". However, when you press Alt +/, The onClick option is not displayed, it suddenly seems a problem to me.

1 public class TestButtonActivity extends Activity {2 3 Button btn1, btn2; 4 Toast tst; 5 6 @ Override 7 protected void onCreate (Bundle savedInstanceState) {8 super. onCreate (savedInstanceState); 9 setContentView (R. layout. activity_test_button); 10} 11 12 // note that there is no @ Override label 13 public void onClick (View v) {14 // TODO Auto-generated method stub15 switch (v. getId () {16 case R. id. button1: 17 tst = Toast. makeText (this, "111111111", Toast. LENGTH_SHORT); 18 tst. show (); 19 break; 20 case R. id. button2: 21 tst = Toast. makeText (this, "222222222", Toast. LENGTH_SHORT); 22 tst. show (); 23 break; 24 default: 25 break; 26} 27} 28}

In this way, the Click Event of the button can be implemented without declaring the button in the code.

 

The above are four methods for implementing button-click events.

In a rough summary, it is faster to use an anonymous internal class when there are few buttons, such as writing a demo test or logging on to the interface.

When there are many buttons, I chose the third method for convenience.

I feel the most convenient about the fourth method, but I still think that the writing is quite small after reading a lot of code. I still need to study this point for some reason.

 

[NOTE 1] Four methods for responding to click events from Android-Button

What he said

1 public void click(View v){2 ...3 }

I tried the method and an error will be reported during the running. We recommend that you use the sample code above. The time was too short to take a closer look at the cause of the error.

In android, add a click event to you.

Public onCreate (Bundle bundle ){
Button btn = (Button) findViewById (R. id. button1 );
Btn. setOnClickListener (listener );
}
Public onClickListener listener = new onClickListener (this ){
Public void onClick (View paramView ){
// What you want to do
} |
}

Android button add Click Event

First, the number has an initial value. Suppose int num = 0;
Bt. setOnClickListener (new OnClickListener (){
Public void onClick {
Num ++;
TV. setText (num );
}
});