java数组插入元素的三种方法

import java.util.Arrays;

public class Test{

    public static void main(String args[]) throws Exception {

        int array[] = {

      2, 5, -2, 6, -3, 8, 0, -7, -9, 4 };

        Arrays.sort(array);

        int index = Arrays.binarySearch(array, 1);

        System.out.println("元素 1 所在位置（负数为不存在）："

                + index);

        int newIndex = -index - 1;

        array = insertElement(array, 1, newIndex);

        System.out.println("添加元素1后:"+Arrays.toString(array));

    }

    private static int[] insertElement(int original[],

                                       int element, int index) {

        int length = original.length;

        int destination[] = new int[length + 1];

        System.arraycopy(original, 0, destination, 0, index);

        destination[index] = element;

        System.arraycopy(original, index, destination, index

                + 1, length - index);

        return destination;

    }

}

/* 输出结果:

元素 1 所在位置（负数为不存在）：-6

添加元素1:[-9, -7, -3, -2, 0, 1, 2, 4, 5, 6, 8]

 */

import java.util.*;

public class Test{

    public static void main(String[] args) {

        String[] arr = {

     "ID", "姓名"};

        // 将数组转化为集合 1

        List<String> list1 = Arrays.asList(arr);

        List<String> list2 = new ArrayList<>();

        // 定义集合 2 、并向其中添加元素: 性别

        list2.add("性别");

        List<String> List = new ArrayList<String>();

        // 定义新集合、将集合1、2中的元素添加到新集合

        List.addAll(list1);

        List.addAll(list2);

        // 将新集合转化回新数组

        String[] newArr = List.toArray(new String[List.size()]);

        System.out.println(Arrays.toString(newArr));

    }

}

/* 输出结果: [ID, 姓名, 性别]  */