83 lines
1.8 KiB
Java
83 lines
1.8 KiB
Java
// patterns/adapt/Adapter.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// Variations on the Adapter pattern.
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// {java patterns.adapt.Adapter}
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package patterns.adapt;
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class WhatIHave {
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public void g() {}
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public void h() {}
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}
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interface WhatIWant {
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void f();
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}
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class ProxyAdapter implements WhatIWant {
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WhatIHave whatIHave;
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ProxyAdapter(WhatIHave wih) {
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whatIHave = wih;
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}
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@Override public void f() {
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// Implement behavior using
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// methods in WhatIHave:
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whatIHave.g();
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whatIHave.h();
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}
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}
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class WhatIUse {
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public void op(WhatIWant wiw) {
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wiw.f();
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}
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}
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// Approach 2: build adapter use into op():
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class WhatIUse2 extends WhatIUse {
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public void op(WhatIHave wih) {
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new ProxyAdapter(wih).f();
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}
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}
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// Approach 3: build adapter into WhatIHave:
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class WhatIHave2 extends WhatIHave
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implements WhatIWant {
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@Override public void f() {
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g();
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h();
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}
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}
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// Approach 4: use an inner class:
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class WhatIHave3 extends WhatIHave {
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private class InnerAdapter implements WhatIWant{
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@Override public void f() {
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g();
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h();
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}
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}
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public WhatIWant whatIWant() {
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return new InnerAdapter();
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}
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}
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public class Adapter {
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public static void main(String[] args) {
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WhatIUse whatIUse = new WhatIUse();
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WhatIHave whatIHave = new WhatIHave();
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WhatIWant adapt= new ProxyAdapter(whatIHave);
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whatIUse.op(adapt);
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// Approach 2:
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WhatIUse2 whatIUse2 = new WhatIUse2();
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whatIUse2.op(whatIHave);
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// Approach 3:
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WhatIHave2 whatIHave2 = new WhatIHave2();
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whatIUse.op(whatIHave2);
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// Approach 4:
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WhatIHave3 whatIHave3 = new WhatIHave3();
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whatIUse.op(whatIHave3.whatIWant());
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}
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}
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