java design pattern - strategy pattern

Strategy pattern also known as Policy Pattern. 

挺有意思的看了一个例子，将不通的Algorithm 设计为不同的类，然后通过一个Context 类联系在一起。

package policypattern;

interface Strategy{
    public void sort(int[] numbers);
}

class MyContext{
    private Strategy strategy;

    //constructor
    public MyContext(Strategy strategy){
        this.strategy= strategy;
    }

    public void arrange(int[] input){
        strategy.sort(input);
    }
}

class BubbleSort implements Strategy{
    @Override
    public void sort(int[] numbers){
        System.out.println("Sorting array using bubble sort strategy");
    }
}

class InsertionSort implements Strategy{

    @Override
    public void sort(int[] numbers){
        System.out.println("Sorting array with insertion sort strategy");
    }
}


class MergeSort implements Strategy{
    @Override
    public void sort(int[] numbers){
        System.out.println("Sorting array using merge sort strategy");
    }
}

class QuickSort implements Strategy{
    @Override
    public void sort(int[] numbers){
        System.out.println("Sorting array using quick sort strategy");
    }
}



public class StrategyPatternDemo {
    public static void main(String[] args){
        int[] var = {1,2,9,6,4,10};

        //provide any strategy to do the sorting
        MyContext ctx = new MyContext(new BubbleSort());
        ctx.arrange(var);

        //we can change the Strategy without changing Context class
        ctx = new MyContext(new QuickSort());
        ctx.arrange(var);
    }
}