java 动态实现数组增删（韩顺平）

一.简单的数组扩容

        int[] arr1 = {1,2,3};
        int[] arrNew = new int[arr1.length + 1];
        for (int i = 0; i < arr1.length; i++) {
            arrNew[i] = arr1[i];
        }
        arrNew[arr1.length] = 5;
        arr1 = arrNew;//将arrnew的地址传给arr1后，数组arr1将消失
        for (int i = 0; i < arr1.length + 1; i++) {
            System.out.println(arrNew[i]);
        }
        for (int i = 0; i < arr1.length; i++) {
            System.out.println(arr1[i]);
        }

二.连续进行数组扩容

不知道用户什么时候结束扩容，用do-while + break语句来实现

        Scanner myscanner = new Scanner(System.in);

        int[] arr = {1,2,3};

        do {
            int[] arrnew = new int[arr.length + 1];

            for (int i = 0; i < arr.length; i++) {
                arrnew[i] = arr[i];
            }

            arrnew[arrnew.length - 1] = myscanner.nextInt();
            arr = arrnew;

            for (int i = 0; i < arrnew.length; i++) {
                System.out.println(arrnew[i]);
            }

            System.out.println("是否继续输入");
            char key = myscanner.next().charAt(0);
            if (key == 'n') break;//输入n结束扩容
        }while (true);

三.数组删减

        int[] arr = {1,2,3};
        Scanner myscanner = new Scanner(System.in);
        do {

            int[] newarr = new int[arr.length - 1];

            for (int i = 0; i < newarr.length; i++) {
                newarr[i] = arr[i];
            }

            arr = newarr;
            char s = myscanner.next().charAt(0);

            if (newarr.length == 0 || s == 'n') break;//输入n或数组大小为0时结束缩减

            for (int i = 0; i < newarr.length; i++) {
                System.out.println(newarr[i]);
            }

        }while (true);