Problem:
If want to reuse the existing class, but its interface does not meet the new requirement.
Solution:
Adapter pattern.
1) This is new interface we want to implement.
======================== Target.java ====================
package test.pattern.adapter;
public interface Target {
public void methodA();
public void methodB();
}
2) This is the existing class we have.
======================= Adaptee.java ================
package test.pattern.adapter;
public class Adaptee {
public void methodA() {
System.out.println("it is method A.");
}
}
3) This is an adapter class to implement above new interface Target.java
=================== Adapter.java =====================
package test.pattern.adapter;
public class Adapter extends Adaptee implements Target {
public void methodB() {
System.out.println("it is method B.");
}
}
4) This is another adapter to implement above new interface Target.java
=================== Adapter2.java ====================
package test.pattern.adapter;
public class Adapter2 implements Target {
private Adaptee adaptee;
public Adapter2(Adaptee adaptee) {
this.adaptee = adaptee;
}
public void methodA() {
this.adaptee.methodA();
}
public void methodB() {
System.out.println("this is method B.");
}
}
5) test class
============== Client.java ======================
package test.pattern.adapter;
public class Client {
public static void main(String[] args) {
Target adapter = new Adapter();
adapter.methodA();
adapter.methodB();
Adaptee adaptee = new Adaptee();
Target adapter2 = new Adapter2(adaptee);
adapter2.methodA();
adapter2.methodB();
}
}
This is output:
it is method A.
it is method B.
it is method A.
this is method B.
