Common Interface Usage and usage in android listening

 

Common usage: callback method interface, dynamic binding to upward transformation, constant interface.

Callback method interface:

 

Java code

Public interface ICallback {

Public void func ();

}

 

Public class Caller {

ICallback callback;

Public void doCallback (){

Callback. func ();

}

 

Public void setCallback (ICallback callback ){

This. callback = callback;

}

 

}

 

Public class MainClass {

Public MainClass (){

}

 

Public static void main (String [] args ){

Caller caller = new Caller ();

Caller. setCallback (new ICallback (){

Public void func (){

System. out. println ("dosomething ");

}

});

Caller. doCallback ();

}

}

 

Upward Transformation:

 

Java code

Interface People {

Void peopleList ();

}

Class Student implements People {

Public void peopleList (){

System. out. println ("I'm a student .");

}

}

Class Teacher implements People {

Public void peopleList (){

System. out. println ("I'm a teacher .");

}

}

Public class Example {

Public static void main (String args []) {

People a; // declare interface Variables

A = new Student (); // instantiation, where the interface variable stores object references

A. peopleList (); // interface callback

A = new Teacher (); // instantiate, the interface variable stores the object reference

A. peopleList (); // interface callback

}

}

Result:

I'm a student.

I'm a teacher.

 

 

 

The constant interface is not used as an example. Here is an example of a callback interface in Android.

Instance (simulate a Button click event listener on the Android Interface ):

1. Define the interface

 

 

Java code

Public interface OnClickListener {

 

Public void OnClick (Button B );

 

}

 

 

 

2. Define the Button

Java code

Public class Button {

 

OnClickListener listener;

 

Public void click (){

 

Listener. OnClick (this );

 

}

 

Public void setOnClickListener (OnClickListener listener ){

 

This. listener = listener;

 

}

 

}

 

3. Assign the OnClickListener interface object to the interface member of the Button.

Java code

Public class MyActivity extends Activity {

 

Button button = new Button ();

 

Button. setOnClickListener (new OnClickListener (){

 

Public void OnClick (Button B ){

 

System. out. println ("clicked ");

 

}

 

});

 

}

 

}

 

5-digit space,