Collections class (collections continued)

Collections class (collections continued)

The collections class is a tool class of collections, similar to the tool class Arrays of arrays

Define a large number of static methods

• Methods to synchronize collection objects

• How to sort List

package day4;

import java.util.ArrayList;
import java.util.Collections;

public class CollectionDemo {
    
    
    public static void main(String[] args) {
    
    
        ArrayList<String> list1 = new  ArrayList<>();
        list1.add("a");
        list1.add("a");
        list1.add("a");
        list1.add("a");

        ArrayList<String> list = new  ArrayList<>();
        list.add("c");
        list.add("a");
        list.add("b");
        list.add("d");
        list.add("e");

        Collections.sort(list); //根据指定的比较器引起的顺序对指定的列表进行排序。
        System.out.println(Collections.binarySearch(list, "b"));//使用二叉搜索算法搜索指定对象的指定列表

        Collections.addAll(list,"x","y","z");
         Collections.copy(list1, list);//被复制的列表中的内容长度不能小于复制列表的长度
         Collections.fill(list, "A");
        Collections.reverse(list);
        Collections.swap(list,0, 1);
        System.out.println(list);
        System.out.println(Collections.max(list));
        System.out.println(list1);
    }
}