Strategy Pattern

The intent of Strategy pattern is to define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets a class behavior or its algorithm can be changed at run time. It captures the abstraction in an interface, and provides implementation details in derived classes.

Here is one example to demonstrate Decorator pattern implementation and usage.

Strategy class


package net.tecbar.designpattern.strategy;

public interface Strategy {
	void doOpeation();
}

package net.tecbar.designpattern.strategy;

public interface Strategy {

void doOpeation();

}

Concrete strategy classes


package net.tecbar.designpattern.strategy;

public class StrategyA implements Strategy {

	@Override
	public void doOpeation() {
		System.out.println("execute algorithm in StrategyA");
	}
}

package net.tecbar.designpattern.strategy;

public class StrategyA implements Strategy {

@Override

public void doOpeation() {

System.out.println("execute algorithm in StrategyA");

}


package net.tecbar.designpattern.strategy;

public class StrategyB implements Strategy {

	@Override
	public void doOpeation() {
		System.out.println("execute algorithm in StrategyB");
	}
}

package net.tecbar.designpattern.strategy;

public class StrategyB implements Strategy {

@Override

public void doOpeation() {

System.out.println("execute algorithm in StrategyB");

}

Context class


package net.tecbar.designpattern.strategy;

public class Context {
	private Strategy strategy;
	
	public Context(Strategy strategy) {
		this.strategy = strategy;
	}
	
	public void myMethod() {
		strategy.doOpeation();
	}
}

package net.tecbar.designpattern.strategy;

public class Context {

private Strategy strategy;

public Context(Strategy strategy) {

this.strategy = strategy;

}

public void myMethod() {

strategy.doOpeation();

}

Client


package net.tecbar.designpattern.strategy;

public class StrategyDemo {

	public static void main(String[] args) {
		Context ctx = new Context(new StrategyA());
		ctx.myMethod();
		
		Context ctx2 = new Context(new StrategyB());
		ctx2.myMethod();
	}
}