Java basics-one-dimensional array

Preface: Why do you need an
array? An array is a variable used to store data of the same data type.
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【Note:Array index starts from 0], if you don’t pay attention, the following exception will appear:Array subscript out of bounds exception

Declaration and definition of one-dimensional arrays

Declare the array: int[] a;
Assign Kong Jian: a = new int[5];
Assignment: a[0] = 8;
Processing data: a[0]=a[0]*10;

Common ways to define one-dimensional arrays:
int[] a =new int[5];
a[0] =8,a[1]=34...
int[] a = {12,23,23};

【example】

1. Calculate the average score of 5 students
1. Useless for loop

int [ ] scores = {60, 80, 90, 70, 85};
double avg = (scores[0] + scores[1] + scores[2] + scores[3] + scores[4])/5;
System.out.println(avg);

2. Use a for loop

int [ ] scores = {60, 80, 90, 70, 85};
int sum = 0;
double avg;
for(int i = 0; i < scores.length; i++){
    sum = sum + scores[i];
}
System.out.println(avg = sum / scores.length);

The actual address of the data in memory
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2. Calculate the sum of all elements in an array, and determine whether the input number is in the array

int []arr = {8,4,2,1,23,344,12};
int sum = 0;
for (int x:arr) {
    System.out.print(x+"\t");
    sum+=x;
}
System.out.println("\n总和为"+sum);	 		//输处数组中所有元素的总和
System.out.println("请输入一个数");         //输入一个数看是否为数组中元素
Scanner sc = new Scanner(System.in);
int input = sc.nextInt();
boolean tag =false;
for (int i = 0; i < arr.length; i++) {
    if (input == arr[i])
        tag = true;
}
if (tag) {
    System.out.println(tag);
} else {
    System.out.println(tag);
}

[Note: The output here is a bit basic, we will talk about the Arrays.toString(a) method to quickly print all elements of the array]

The results show:
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Three, find the value of the largest element in an array

int a[] = new int[10];                   //求最大值
for (int i = 0; i < a.length; i++) {
    a[i] = (int)(Math.random()*100);	//这边就用随机数代替输入
}
int max = a[0];							//默认第一个元素为最大值，同理求最小值也是一样
for (int i : a) {
    System.out.print(i+"\t");
    if(max<=i)
        max = i;
}
System.out.println("\n"+max);

The results show:
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Fourth, insert a number in the array

int[] a = {99,85,33,22,-43};             //数组插入元素，采用 从后往前比较
int[] b = Arrays.copyOf(a,6);
System.out.println(Arrays.toString(a));
int num = 100;							//要插入的数，你也可以改成自己输入
int x = 1;
for (int i = b.length-2; i >=0 ; i--) {
    if(b[i]<num){
        b[i+1] = b[i];        			//比num小的元素，往后移位
    }else {
        b[i+1] = num;        		   //比num大的，将num插入到该元素后面
        x = 2;
        break;
    }
}
if(x==1){                   		  //如果没有没有比num大的，将num插在数组第一位
    b[0] = num;
}
System.out.println(Arrays.toString(b));

The results show that:
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