Strategy Pattern

Strategy Pattern: defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.

Example

Car.java

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package com.strategypattern.example;   public abstract class Car {  EngineType engineType;  BodyStyle bodyStyle;    public void setEngineType(EngineType engineType) {   this.engineType = engineType;  }    public void setBodyStyle(BodyStyle bodyStyle) {   this.bodyStyle = bodyStyle;  }    public void drive() {   engineType.engine();   bodyStyle.body();  }   }

EngineType.java

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package com.strategypattern.example;   public interface EngineType {  public void engine(); }

BodyStyle.java

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package com.strategypattern.example;   public interface BodyStyle {  public void body(); }

GasolineEngine.java

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package com.strategypattern.example;   public class GasolineEngine implements EngineType{    @Override  public void engine() {   System.out.println("Engine Type : Gasoline");  }   }

DieselEngine.java

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package com.strategypattern.example;   public class DieselEngine implements EngineType{    @Override  public void engine() {   System.out.println("Engine Type : Diesel");  }   }

CompactSedan.java

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package com.strategypattern.example;   public class CompactSedan implements BodyStyle{    @Override  public void body() {   System.out.println("Body Style : Compact Sedan");  }   }

Hatchback.java

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package com.strategypattern.example;   public class Hatchback implements BodyStyle{    @Override  public void body() {   System.out.println("Body Style : Hatchback");  }   }

HondaCivic.java

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package com.strategypattern.example;   public class HondaCivic extends Car {  public HondaCivic(){   engineType = new GasolineEngine();   bodyStyle = new CompactSedan();  }     public String toString(){   return "Honda Civic";  } }

SuzukiSwift.java

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package com.strategypattern.example;   public class SuzukiSwift extends Car {  public SuzukiSwift(){   engineType = new GasolineEngine();   bodyStyle = new Hatchback();  }     public String toString(){   return "Suzuki Swift";  } }

CarTestDrive.java

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package com.strategypattern.example;   public class CarTestDrive {  public static void main(String[] args) {   Car suzukiSwift = new SuzukiSwift();   System.out.println("You are Driving " + suzukiSwift);   suzukiSwift.drive();       Car hondaCivic = new HondaCivic();   System.out.println("You are Driving " + hondaCivic);   hondaCivic.drive();   //Hand Civic is giving low mileage on Gasoline,so Engine Type changed to Diesel   hondaCivic.setEngineType(new DieselEngine());   hondaCivic.drive();     } }

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