Java Collections shuffle()

shuffle() 工作原理是随机置换指定列表元素。有以下两个重载方法：

• Java Collections shuffle(list) 方法
• Java Collections shuffle(list, random) 方法

1 语法

public static void shuffle(List<?> list)  

或

public static void shuffle(List<?> list, Random random)  

2 参数

list：这是将被改组的列表。

random：它是随机性的来源，用于随机排列列表。

3 返回值

无

4 Collections shuffle()示例1

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java Collections.shuffle的例子
 */
import java.util.*;

public class Demo {

    public static void main(String[] args) {
        List<String> list = Arrays.asList("A", "B", "C", "D");
        System.out.println("List before Shuffle : "+list);
        Collections.shuffle(list);
        System.out.println("List after shuffle : "+list);
    }
}

输出结果为：

List before Shuffle : [A, B, C, D]
List after shuffle : [D, A, B, C]

5 Collections shuffle()示例2

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java Collections.shuffle的例子
 */
import java.util.*;

public class Demo {

    public static void main(String[] args) {
        //Create linked list object
        LinkedList<Integer> list = new LinkedList<Integer>();
        //Add values in the list
        list.add(10);
        list.add(-20);
        list.add(50);
        list.add(90);
        list.add(-15);
        System.out.println("List before Shuffle : "+list);
        Collections.shuffle(list);
        System.out.println("List after shuffle : "+list);
    }
}

输出结果为：

List before Shuffle : [10, -20, 50, 90, -15]
List after shuffle : [-15, 10, 90, 50, -20]

6 Collections shuffle()示例3

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java Collections.shuffle的例子
 */
import java.util.*;

public class Demo {

    public static void main(String[] args) {
        //Create linked list object
        LinkedList<Integer> list = new LinkedList<Integer>();
        //Add values in the list
        list.add(45);
        list.add(20);
        list.add(55);
        list.add(90);
        list.add(15);
        System.out.println("List before Shuffle = "+list);
        //We use Random() to shuffle given list.
        Collections.shuffle(list, new Random());
        System.out.println("Shuffled List with Random() = "+list);
        //We use Random(3) to shuffle given list.
        Collections.shuffle(list, new Random(3));
        System.out.println("Shuffled List with Random(3) = "+list);
    }
}

输出结果为：

List before Shuffle = [45, 20, 55, 90, 15]
Shuffled List with Random() = [15, 45, 20, 90, 55]
Shuffled List with Random(3) = [90, 45, 15, 20, 55]

7 Collections shuffle()示例4

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java Collections.shuffle的例子
 */
import java.util.*;

public class Demo {

    public static void main(String[] args) {
        List<String> list = Arrays.asList("one", "two", "three", "four");
        System.out.println(list);
        Collections.shuffle(list, new Random(2));
        System.out.println(list);
    }
}

输出结果为：

[one, two, three, four]
[four, two, one, three]