collection常用方法(小工具)

package Collection;

import java.util.*;

/**
 * collection   小工具
 *
 * @author liu
 */
public class Demo01 {
    public static void main(String[] args) {
        List arrayList = new ArrayList<>();
        arrayList.add(1);
        arrayList.add(12);
        arrayList.add(21);
        arrayList.add(15);
        arrayList.add(15);
        arrayList.add(16);

        //sort排序
        System.out.println("排序前：" + arrayList);
        Collections.sort(arrayList);
        System.out.println("排序后：" + arrayList);


        //binarySearch查找
        System.out.println("--------查找-----------");
        int i = Collections.binarySearch(arrayList, 15);
        System.out.println(i);

        //copy复制,需要添加元素
        System.out.println("--------复制-----------");
        List listt = new ArrayList<>();
        for (int k = 0; k < arrayList.size(); k++) {
            listt.add(0);
        }
        Collections.copy(listt, arrayList);
        System.out.println(listt);

        //reverse反转
        System.out.println("--------反转-----------");
        Collections.reverse(listt);
        System.out.println(listt);

        //shuffle打乱
        System.out.println("--------打乱-----------");
        Collections.shuffle(listt);
        System.out.println(listt);

        //补充list转数组
        System.out.println("--------集合转数组-----------");
        Integer[] A = listt.toArray( new Integer[10]);
        System.out.println(Arrays.toString(A));

        //数组转集合
        System.out.println("--------数组转集合-----------");
        String[] name ={"张三","李思","王五"};
        //转集合后，是一个受限集合，不能添加、删除
        List strList = Arrays.asList(name);
        //strList.add("2");
        //strList.remove(0);
        System.out.println(strList);

        //数组转集合，类型不能为int,需要修改为包装类型
        Integer[] nums = {1,2,5,7,1,1,22};
        List list1 =Arrays.asList(nums);
        System.out.println(list1);
    }
}