// patterns/adapt/Adapter.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Variations on the Adapter pattern
// {java patterns.adapt.Adapter}
package patterns.adapt;

class WhatIHave {
 public void g() {}
 public void h() {}
}

interface WhatIWant {
 void f();
}

class ProxyAdapter implements WhatIWant {
 WhatIHave whatIHave;
 ProxyAdapter(WhatIHave wih) {
 whatIHave = wih;
 }
 @Override
 public void f() {
 // Implement behavior using
 // methods in WhatIHave:
 whatIHave.g();
 whatIHave.h();
 }
}

class WhatIUse {
 public void op(WhatIWant wiw) {
 wiw.f();
 }
}

// Approach 2: build adapter use into op():
class WhatIUse2 extends WhatIUse {
 public void op(WhatIHave wih) {
 new ProxyAdapter(wih).f();
 }
}

// Approach 3: build adapter into WhatIHave:
class WhatIHave2 extends WhatIHave
implements WhatIWant {
 @Override
 public void f() {
 g();
 h();
 }
}

// Approach 4: use an inner class:
class WhatIHave3 extends WhatIHave {
 private class InnerAdapter implements WhatIWant{
 @Override
 public void f() {
 g();
 h();
 }
 }
 public WhatIWant whatIWant() {
 return new InnerAdapter();
 }
}

public class Adapter {
 public static void main(String[] args) {
 WhatIUse whatIUse = new WhatIUse();
 WhatIHave whatIHave = new WhatIHave();
 WhatIWant adapt= new ProxyAdapter(whatIHave);
 whatIUse.op(adapt);
 // Approach 2:
 WhatIUse2 whatIUse2 = new WhatIUse2();
 whatIUse2.op(whatIHave);
 // Approach 3:
 WhatIHave2 whatIHave2 = new WhatIHave2();
 whatIUse.op(whatIHave2);
 // Approach 4:
 WhatIHave3 whatIHave3 = new WhatIHave3();
 whatIUse.op(whatIHave3.whatIWant());
 }
}