Collections

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<String> 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");
        
    }
}