二维不规则数组的打印

public class Test {
        public static void main(String[] args) {
            int data[][] = new int[][]{ //定义数组
                    {1,2,3,4,5},{2,4,3,2},{1}
            };

            //for循环
            for(int x=0; x<data.length; x++){
                for(int y=0; y<data[x].length; y++){
                    System.out.print(data[x][y] + " ");
                }
                System.out.println("\t");
            }

            //foreach循环
            for(int temp[] : data){ //第一行data[]数值赋值给temp[]
                for(int num : temp){
                    System.out.print(num + " ");
                }
                System.out.println("\t");
            }
        }
    }

打印数组结构

数组的冒泡排序

对一列数组进行简单的两两比较升序排列

public class SortArrayTest {
    public static void main(String args[]){
        int[] arr = new int[] {23,12,45,32,14,66,89,4,3};
        for(int j=0; j<arr.length-1;j++){
            for(int i=0; i<arr.length-1-j;i++){
                if (arr[i] > arr[i+1]) {
                    int tmp = arr[i];
                    arr[i] = arr[i+1];
                    arr[i+1] = tmp;
                }
            }
        }
        //输出数组顺序
        for (int num: arr) {
            System.out.print(num + " ");
        }
    }
}

结果

数组转置

数组转置举例：
转置前 [1,2,3,4,5,6,7,8,9]
转置后 [9,8,7,6,5,4,3,2,1]

方法一
定义一个新的数组来保存转置后的数据

public class SortArrayTest {
    public static void main(String args[]){
        int[] arr = new int[] {1,2,3,4,5,6,7,8,9};
        int[] tmp = new int[arr.length];

        for(int i=0; i<=arr.length-1;i++){
            int cc = arr[i];
            tmp[arr.length-1-i] = cc;
        }

        for (int num: tmp) {
            System.out.print(num + " ");
        }
    }
}

方法二
在一个数组中互换首尾数据

public class SortArrayTest {
    public static void main(String args[]){
        int[] arr = new int[] {1,2,3,4,5,6,7,8,9};
        int center = arr.length/2;
        int head = 0;
        int tail = arr.length-1;

        for(int i=0; i<=center;i++){
            int tmp;
            tmp = arr[head];
            arr[head] = arr[tail];
            arr[tail] = tmp;

            head ++;
            tail --;
        }

        for(int num : arr){
            System.out.print(num + " ");
        }
    }
}