【Java Collections工具类】

package com.yuzhenc.collection;

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

/**
 * @author: yuzhenc
 * @date: 2022-03-09 23:10:21
 * @desc: com.yuzhenc.collection
 * @version: 1.0
 */
public class Test19 {
    public static void main(String[] args) {
        //addAll
        ArrayList<String> arrayList = new ArrayList<>();
        arrayList.add("abc");
        arrayList.add("def");
        arrayList.add("ghi");
        Collections.addAll(arrayList,"jkl","mno");
        System.out.println(arrayList);//[abc, def, ghi, jkl, mno]
        //升序排序
        Collections.sort(arrayList);
        System.out.println(arrayList);//[abc, def, ghi, jkl, mno]
        //二分查找
        System.out.println(Collections.binarySearch(arrayList,"ghi"));//2
        //copy替换
        ArrayList<String> arrayList1 = new ArrayList<>();
        arrayList1.add("aa");
        arrayList1.add("bb");
        System.out.println(arrayList);//[abc, def, ghi, jkl, mno]
        System.out.println(arrayList1);//[aa, bb]
        Collections.copy(arrayList,arrayList1);
        System.out.println(arrayList);//[aa, bb, ghi, jkl, mno]
        System.out.println(arrayList1);//[aa, bb]
        //Collections.copy(arrayList1,arrayList);//拿长度长的复制到长度短的，会直接报错
        //fill填充
        Collections.fill(arrayList,"zzz");
        System.out.println(arrayList);//[zzz, zzz, zzz, zzz, zzz]
    }
}