1.查询元素

import java.util.Arrays;import java.util.Scanner;public class TestArry2 {    public static void main(String[] args) {        //数组查询        int arr[] = new int[]{12, 34, 55, 11, 151};        System.out.println(Arrays.toString(arr));        System.out.println("输入要查找的数");        Scanner scanner = new Scanner(System.in);        int num = scanner.nextInt();        int index = query(arr, num);        if (index > 0) {            System.out.println("索引为" + index);        } else {            System.out.println("查无次数");        }    }    public static int query(int arr[], int num) {        int index = -1;        for (int i = 0; i <= arr.length - 1; i++) {            if (arr[i] == num) {                index = i;                break;            }        }        return index;    }}

2.添加元素

import java.util.Arrays;import java.util.Scanner;public class TestArry3 {    public static void main(String[] args){    //添加元素        int arr[]=new int[]{12,43,65,77,11};        System.out.println(Arrays.toString(arr));        Scanner scanner=new Scanner(System.in);        System.out.println("输入要添加的元素");        int num=scanner.nextInt();        System.out.println("输入要插入的索引位置");        int n=scanner.nextInt();        add(arr,n,num);        System.out.println(Arrays.toString(arr));    }    public static  void add(int arr[],int n,int num){        for (int i=arr.length-1;i>=(n+1);i--){            arr[i]=arr[i-1];        }        arr[n]=num;    }}

3.删除元素

import java.util.Arrays;import java.util.Scanner;public class TestArry4 {    public static void main(String[] args) {        //删除元素        int arr[] = new int[]{12, 34, 56, 77, 100};        System.out.println(Arrays.toString(arr));        Scanner scanner = new Scanner(System.in);        System.out.println("输入要删除的元素");        int num = scanner.nextInt();        int index = query(arr, num);        delete(arr, index);        System.out.println(Arrays.toString(arr));    }    //查找索引    public static int query(int arr[], int num) {        int index = -1;        for (int i = 0; i <= arr.length - 1; i++) {            if (arr[i] == num) {                index = i;                break;            }        }        return index;    }    //删除元素    public static void delete(int arr[], int index) {        for (int i = index; i <= arr.length - 2; i++) {            arr[i] = arr[i + 1];        }        arr[arr.length - 1] = 0;    }}