Java 基本类型数组、包装类数组、集合之间的相互转换（以及遍历方法）

import java.util.*;
import java.util.stream.Collectors;


import static java.util.Arrays.*;

public class ZhuanHuan{
     
    public static void main(String[] args) {
     
        //数组: int[]
        int[] arrayInt = new int[]{
     1,2,3,4,5,6};
        printElement(arrayInt);

        //原生数组转包装类数组: int[] 2 Integer[]
        Integer[] arrayInter = Arrays.stream(arrayInt).boxed().toArray(Integer[]::new);
        printElement(arrayInter);

        //*包装类数组转List/ArrayList: Integer[] 2 List
        List<Integer> listInter = Arrays.asList(arrayInter);
        printElement(listInter);

        //*List/ArrayList转包装类数组: List 2 Integer[]
        Integer[] arrayInter2 = listInter.toArray(new Integer[listInter.size()]);
        printElement(arrayInter2);

        //包装类数组转原生数组: Integer[] 2 int[]
        int[] arrayInt2 = Arrays.stream(arrayInter2).mapToInt(Integer::valueOf).toArray();
        printElement(arrayInt2);

        //原生数组转List/ArrayList: int[] 2 List
        List<Integer> listInter2 = Arrays.stream(arrayInt2).boxed().collect(Collectors.toList());
        printElement(listInter2);

        //List/ArrayList转原生数组： List 2 int[]
        int[] arrayInt3 = listInter2.stream().mapToInt(Integer::valueOf).toArray();
        printElement(arrayInt3);

    }
    //原生数组遍历输出
    private static void printElement(int[] arr){
     
        for(int i=0;i<arr.length;i++){
     
            System.out.println(arr[i]);
        }
    }
    //包装类数组遍历输出
    private static void printElement(Integer[] arr){
     
        for(int i=0;i<arr.length;i++){
     
            System.out.println(arr[i]);
        }
    }
    //List遍历输出
    private static void printElement(List list){
     
        Iterator iter = list.iterator();
        while(iter.hasNext()){
     
            System.out.println(iter.next());
        }
    }

}