数组的简单认识及其学习（二）

public static void main(String[] args) {
        //静态初始化   多维数组
        int[][] arr1 = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
        System.out.println(arr1);//不转
        System.out.println(Arrays.toString(arr1));//之前的方式
        System.out.println(Arrays.deepToString(arr1));//多维数组转化
        //动态初始化
        int[][] ints = new int[5][2]; //外层5个  内层2个  数据5*2=10
        for (int i = 0; i < ints.length; i++) {
            for (int j = 0; j < ints[i].length; j++) {
                //(Math.random() *100)  随机数  1-99 的范围
                ints[i][j] = (int) (Math.random() * 100);
                System.out.print(ints[i][j] + "\t");
            }
        }
        //System.out.print("\t");
        System.out.println(Arrays.deepToString(ints));
        //遍历数组
        for (int i = 0; i < arr1.length; i++) {
            for (int j = 0; j < arr1[i].length; j++) {
                System.out.print(arr1[i][j] + "\t");
            }
            System.out.println();
        }
        //本质 一维数组  外层是3层  里层不断递增
        int[][] ints1 = new int[3][];
        ints1[0] = new int[]{1,2};
        ints1[1] = new int[]{3,4,5};
        ints1[2] = new int[]{6,7,8,9};
        System.out.println(Arrays.deepToString(ints1));
        //更多的维度数组
        int[][][] arr3={
                {{11,12}},{{13,14}},{{15,16}}
        };
        System.out.println(Arrays.deepToString(arr3));

[[I@5a39699c
[[I@3cb5cdba, [I@56cbfb61, [I@1134affc]
[[1, 2, 3], [4, 5, 6], [7, 8, 9]]
83  36  76  96  61  86  31  46  64  7 [[83, 36], [76, 96], [61, 86], [31, 46], [64, 7]]
1 2 3 
4 5 6 
7 8 9 
[[1, 2], [3, 4, 5], [6, 7, 8, 9]]
[[[11, 12]], [[13, 14]], [[15, 16]]]

public static void main(String[] args) {
        //构造数组
        int[] arr= new int[5];
        for (int i = 0; i < arr.length; i++) {
          arr[i]= (int) (Math.random() * 100);
        }
        System.out.println(Arrays.toString(arr));
        //数组倒转
        //第一个和最后一个倒转 以此类推
        //第一个 arr[0] 最后一个 arr[length-1-0]
        //arr[1]  arr[length-1-1]
        //arr[2]   arr[length-1-2]
        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;
        }
        System.out.println(Arrays.toString(arr));
    }

[64, 24, 78, 34, 39]
[39, 34, 78, 24, 64]

public static void main(String[] args) {
        //初始化数组
        int[] nums = new int[5];
        int index = 0;
        int sum = 0;
        int grade = 1;
        double avg = 0;
        //记录输入
        Scanner scan = new Scanner(System.in);
        System.out.println("请输入数字，负数结束流程");
        while (true){
            int temp = scan.nextInt();
            if (temp < 0){
                break;
            }
            nums[index] = temp;
            sum = sum + temp;
            avg = (double) sum / grade;
            grade = grade +1;
            if (++index > nums.length - 1){
                nums = Arrays.copyOf(nums,nums.length+5);
            }
        }
        scan.close();
//      System.out.println(Arrays.toString(nums));
//      System.out.println(sum);
        System.out.println("平均数是="+avg);
        for (int i = 0 ;i < nums.length;i++){
            if (nums[i] > avg){
                System.out.print("比平均数大的值是="+nums[i]+"\t");
            }
        }
    }

请输入数字
65
36
59
2365
5
4
1
8
56
-4
平均数是288.77777777777777
比平均数大的值是2365

public static void main(String[] args) {
        //冒泡排序  构造数组
        int[] ints = new int[8];
        for (int i = 0; i < ints.length - 1; i++) {
            ints[i] = (int) (Math.random() * 100);
        }
        System.out.println("初始默认值是"+Arrays.toString(ints));
        //轮次
        for (int i = 0; i < ints.length - 1; i++) {
            //比较的次数
            // 1次： 下标  0 -- ints.length-1
            // 下标： 1 -- ints.length-1  类推
            //循环的边界
            //j=ints.length-1-i-1
            //j+1=ints.length--1-i
            for (int j = 0; j < ints.length-1-i-1; j++) {
              //从大到小
                if (ints[j] < ints[j+1]) {
                    int temp=ints[j];
                    ints[j]=ints[j+1];
                    ints[j+1]=temp;
                }
            }
            //打印完整的排序过程
            System.out.println(Arrays.toString(ints));
        }
    }

[40, 59, 96, 30, 16, 40, 45, 0]
[59, 96, 40, 30, 40, 45, 16, 0]
[96, 59, 40, 40, 45, 30, 16, 0]
[96, 59, 40, 45, 40, 30, 16, 0]
[96, 59, 45, 40, 40, 30, 16, 0]
[96, 59, 45, 40, 40, 30, 16, 0]
[96, 59, 45, 40, 40, 30, 16, 0]
[96, 59, 45, 40, 40, 30, 16, 0]