数组元素的赋值与数组复制

举例1：使用简单数组

   public static void arraycp() {
        int[] array1 = new int[]{2, 3, 5, 7, 11, 13, 17, 19};
        int[] array2 = array1;

        for (int i : array2) {
            System.out.println(i);
        }
        System.out.println("---------------------");

        for (int i = 0; i < array2.length; i++) {
            if (array2[i] % 2 == 0) {
                array2[i] = i;
            }
        }

        for (int i : array2) {
            System.out.println(i);
        }
        System.out.println("---------------------");
        System.out.println(array1 == array2);
    }

 

举例2：一个数组，让数组的每个元素去除第一个元素，得到的商作为被除数所在位置的新值。

    public static void arraycp1() {
        int[] array1 = new int[]{2, 3, 5, 7, 11, 13, 17, 19};
        for (int i = 0; i < array1.length; i++) {
            array1[i] = (int) array1[i] / array1[0];
        }
        //遍历
        for (int i : array1) {
            System.out.println(i);
        }
    }

举例3：创建一个长度为6的int型数组，要求数组元素的值都在1-30之间，且是随机赋值。同时，要求元素的值各不相同

    public static void randomArr() {
        int[] arr = new int[6];
        for (int i = 0; i < arr.length; i++) {
            arr[i] = (int) (Math.random() * 30) + 1;
            for (int j = 0; j < i; j++) {
                if (arr[i] == arr[j]) {
                    i--;
                    break;
                }
            }

        }
        for (int i1 : arr) {
            System.out.println(i1);
        }
    }

举例4：扑克牌

案例：遍历扑克牌

遍历扑克牌，效果如图所示：

提示：使用两个字符串数组，分别保存花色和点数，再用一个字符串数组保存最后的扑克牌。 String[] hua = {"黑桃","红桃","梅花","方片"}; String[] dian = {"A","2","3","4","5","6","7","8","9","10","J","Q","K"};

   public static void pic() {
        String[] hua = {"黑桃", "红桃", "梅花", "方片"};
        String[] dian = {"A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K"};

        String[] arr = new String[hua.length * dian.length];
        int k = 0;
        for (int i = 0; i < hua.length; i++) {
            for (int j = 0; j < dian.length; j++) {
                arr[k++] = hua[i] + dian[j];
            }
        }
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + ", ");
            if (i % 13 == 12) {
                System.out.println();
            }
        }
    }

举例5：回形数

从键盘输入一个整数（1~20） ，则以该数字为矩阵的大小，把1,2,3…n*n 的数字按照顺时针螺旋的形式填入其中。

例如： 输入数字2，则程序输出：  1 2  4 3

输入数字3，则程序输出：  1 2 3  8 9 4  7 6 5  输入数字4， 则程序输出：  1 2 3 4  12 13 14 5  11 16 15 6  10 9 8 7

    public static void rectangleNew() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("输入一个数字");
        int n = scanner.nextInt();
        int[][] arr = new int[n][n];

        int count = 0; //要显示的数据
        int maxX = n - 1; //x轴的最大下标
        int maxY = n - 1; //Y轴的最大下标
        int minX = 0; //x轴的最小下标
        int minY = 0; //Y轴的最小下标
        while (minX <= maxX) {
            for (int x = minX; x <= maxX; x++) {
                arr[minY][x] = ++count;
            }
            minY++;
            for (int y = minY; y <= maxY; y++) {
                arr[y][maxX] = ++count;
            }
            maxX--;
            for (int x = maxX; x >= minX; x--) {
                arr[maxY][x] = ++count;
            }
            maxY--;
            for (int y = maxY; y >= minY; y--) {
                arr[y][minX] = ++count;
            }
            minX++;
        }


        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr.length; j++) {
                String space = (arr[i][j] + "").length() == 1 ? "0" : "";
                System.out.print(space + arr[i][j] + " ");
            }
            System.out.println();
        }
        scanner.close();
    }