Java基础快速入门之数组概念、定义格式与动态初始化详解

// 格式1：数据类型[] 数组名;
int[] arr;
// 格式2：数据类型 数组名[];
int arr2[];

数据类型[] 数组名 = new 数据类型[数组长度];

int[] arr = new int[5];   // 可以存储5个int型整数
byte[] bArr = new byte[3]; // 可以存储3个byte型整数

数组名[索引]

int[] arr = new int[3];
System.out.println(arr[0]); // 0
System.out.println(arr[1]); // 0
System.out.println(arr[2]); // 0
arr[0] = 11;
arr[1] = 22;
arr[2] = 33;
System.out.println(arr[0]); // 11
System.out.println(arr[1]); // 22
System.out.println(arr[2]); // 33

int[] arr = new int[3];
arr[0] = 11;
arr[1] = 22;
arr[2] = 33;
System.out.println(arr[0]);
System.out.println(arr[1]);
System.out.println(arr[2]);

int[] arr1 = new int[2];
arr1[0] = 11;
arr1[1] = 22;
int[] arr2 = new int[3];
arr2[0] = 33;
arr2[1] = 44;
arr2[2] = 55;

int[] arr1 = new int[2];
arr1[0] = 11;
arr1[1] = 22;
int[] arr2 = arr1;   // 将arr1记录的地址赋给arr2
arr2[0] = 33;
System.out.println(arr1[0]); // 33
System.out.println(arr1[1]); // 22
System.out.println(arr2[0]); // 33 
System.out.println(arr2[1]); // 22

数据类型[] 数组名 = new 数据类型[]{元素1, 元素2, ...};

数据类型[] 数组名 = {元素1, 元素2, ...};

int[] arr = new int[]{11, 22, 33};
int[] arr2 = {44, 55, 66};

int[] arr = new int[3]; // 索引0~2
System.out.println(arr[3]); // 越界

int[] arr = new int[3];
arr = null;
System.out.println(arr[0]); // 空指针异常

int[] arr = {11, 22, 33, 44, 55};
for (int i = 0; i < arr.length; i++) {
    System.out.println(arr[i]);
}

public static void printArray(int[] arr) {
    System.out.print("[");
    for (int i = 0; i < arr.length; i++) {
        if (i == arr.length - 1) {
            System.out.print(arr[i] + "]");
        } else {
            System.out.print(arr[i] + ", ");
        }
    }
    // 换行
    System.out.println();
}

int[] arr = {12, 45, 98, 73, 60};
int max = arr[0];
for (int i = 1; i < arr.length; i++) {
    if (arr[i] > max) {
        max = arr[i];
    }
}
System.out.println("max:" + max);

Scanner sc = new Scanner(System.in);
int sum = 0;
int[] arr = new int[5];
for (int i = 0; i < arr.length; i++) {
    System.out.println("请输入第" + (i + 1) + "个整数:");
    arr[i] = sc.nextInt();
}
for (int i = 0; i < arr.length; i++) {
    sum += arr[i];
}
System.out.println("sum:" + sum);

int[] arr = {19, 28, 37, 46, 50};
Scanner sc = new Scanner(System.in);
System.out.println("请输入您要查找的元素:");
int num = sc.nextInt();
int index = -1; // 假设不存在 
for (int i = 0; i < arr.length; i++) {
    if (arr[i] == num) {
        index = i;
        break; // 找到后结束循环
    }
}
System.out.println(index);

int[] arr = new int[6];
Scanner sc = new Scanner(System.in);
// 录入评委分数，并保证数据合法
for (int i = 0; i < arr.length; i++) {
    System.out.println("请输入第" + (i + 1) + "个评委的打分:");
    int score = sc.nextInt();
    if (score >= 0 && score <= 100) {
        arr[i] = score;
    } else {
        System.out.println("您的打分输入有误, 请检查是否是0-100之间的");
        i--; // 重新输入本位置
    }
}
// 求最大值
int max = arr[0];
for (int i = 1; i < arr.length; i++) {
    if (arr[i] > max) max = arr[i];
}
// 求最小值
int min = arr[0];
for (int i = 1; i < arr.length; i++) {
    if (arr[i] < min) min = arr[i];
}
// 求和
int sum = 0;
for (int i = 0; i < arr.length; i++) {
    sum += arr[i];
}
// 计算平均分
int avg = (sum - max - min) / 4;
System.out.println(avg);