Collections-类集工具类

定义了若干用于类集和映射的算法,这些算法被定义为静态方法

package com.Set;import java.util.ArrayList;import java.util.Collections;import java.util.List;public class ConnectionsDemo {    public static void main(String[] args) {        List
     
       list = new ArrayList<>();        list.add("A");        list.add("B");        list.add("C");        list.add("D");        for (String string : list) {            System.out.print(string + " ");        }        // 交换顺序        Collections.swap(list, 1, 2);        for (String string : list) {            System.out.print(string + " ");        }        // 自然排序        Collections.sort(list);        for (String string : list) {            System.out.print(string + " ");        }        // 二分法查找        System.out.println(Collections.binarySearch(list, "B"));                //打乱顺序        Collections.shuffle(list);                //填充方法        Collections.fill(list, "E");            }}