Three methods of event listening and three methods of event listening

Three methods of event listening and three methods of event listening

1. Add three buttons to the activity_main.xml file.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:orientation="vertical"    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">    <Button        android:id="@+id/btn1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="@string/btn"        />    <Button        android:id="@+id/btn2"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="@string/btn"        />    <Button        android:id="@+id/btn3"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="@string/btn"        /></LinearLayout>

2,

Method 1: Implement event listening through internal classes

/* Method 1: Implement event listening through internal Classes */btn1.setOnClickListener (new View. onClickListener () {@ Override public void onClick (View v) {Log. I ("tag", "first method: Implement event listening through internal classes"); Toast. makeText (MainActivity. this, "the first button is clicked", Toast. LENGTH_SHORT ). show ();}});

3,

Method 2: Implement event listening through external classes (implement independently)

/* Method 2: Implement event listening through external classes (implemented independently) */btn2.setOnClickListener (new MyOnClickListener () {@ Override public void onClick (View v) {super. onClick (v); Log. I ("tag", "second method: Implement event listening through internal classes") ;}}); class MyOnClickListener implements View. onClickListener {@ Override public void onClick (View v) {Toast. makeText (MainActivity. this, "the second button is clicked", Toast. LENGTH_SHORT ). show ();}}

Note: The second method is to implement event listening through the external class (implemented independently). This method is generally used when multiple components need to implement the same method.

4,

Method 3: Implement event listening through the OnClickListener Interface

Public class MainActivity extends Activity implements View. onClickListener {private Button btn3; protected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); btn3.setOnClickListener (this);}/* method 3: Implement event listening through the OnClickListener interface */@ Override public void onClick (View v) {Log. I ("tag", "method 3: event listening through the OnClickListener interface ");}}

Note: btn3.setOnClickListener (this); here, this Is The onClick method under OnClickListener.