java数组

1.数组初始化的含义以及值：

数组初始化，即在内存开辟连续的n个空间。

初始化：

2.数组三要素：维度，数据类型，内存地址。

3.数组静态初始化与数组动态初始化：

4.数组存储图解：

4.打印数组所有元素

public class demo3_数组1 {
    public static void main(String[] args){
        int[] arr= new int[]{11,22,33,44,55};
        System.out.println(arr[0]);
        System.out.println(arr);
        System.out.println(arr[3]);
        for(int i=0;i<=4;i++)
            System.out.println(arr[i]);
    }
}

数组初始化不允许动静结合。

5.数组倒序输出及遍历（traversal）

public class demo3_数组1 {
    public static void main(String[] args) {


        int[] arr1 = new int[]{11, 22, 33, 44, 55, 66};
        convert(arr1);
    }
    public static void convert(int[] arr) {

        if (arr.length % 2 == 0) {
            for (int i = 0; i < (arr.length) / 2; i++) {
                int temp = arr[i];
                arr[i] = arr[arr.length - 1 - i];
                arr[arr.length - 1 - i] = temp;


            }
            for (int j = 0; j < arr.length; j++) {
                System.out.print(arr[j] + "\t");
            }
        } else {
            for (int i = 0; i < (arr.length - 1) / 2; i++) {
                int temp2 = arr[i];
                arr[i] = arr[arr.length - 1 - i];
                arr[arr.length - 1 - i] = temp2;


            }
            for (int x = 0; x < arr.length; x++) {
                System.out.print(arr[x] + "\t");
            }

        }
    }
        /*
        int max=arr1[0];
        for(int i=1;i<arr1.length;i++){
            if(max<arr1[i]){
                max=arr1[i];

            }


        }
        System.out.print(max);
        /*

        for(int i=0;i<arr1.length;i++) {
            System.out.print(arr1[i] + "\t");
        }
        System.out.println();

        int[] arr2={3,4,5};
        /*
        Traversal(arr1);
        Traversal(arr2);

         */



    /*
    public static void Traversal(int[] arr ){
        for(int i=0;i<arr.length;i++){
            System.out.print(arr[i]+"\t");
        }

    }
    */

}

7.根据索引输出星期

import java.util.Scanner;
public class weekBiao {
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入星期");
        int week=sc.nextInt();
        System.out.println("星期"+getWeek(week));
    }
    public static char getWeek(int week ){
        char [] getWeek= {' ','一','二','三','四','五','六','日',};
        return(getWeek[week]);
    }
}

8.查索引表

import java.util.Scanner;
public class weekBiao {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入星期");
        int week = sc.nextInt();
        System.out.println("星期" + getWeek(week));
        getIdex();

    }

    public static char getWeek(int week) {
        char[] getWeek = {' ', '一', '二', '三', '四', '五', '六', '日',};
        return (getWeek[week]);
    }


    //输入数字求索引
    public static int getIdex(){
        Scanner sc= new Scanner(System.in);
        System.out.println("请输入数字");
        int value=sc.nextInt();
        int [] arr=new int []{11,22,33,44,55};
        for(int i=0;i<arr.length;i++){
            if(arr[i]==value) {
                int index=i;
                System.out.println(index);
            }
        }
        return -1;


    }



}