Java矩阵转置

1、不开辟新数组
注意循环条件，j=i，避免已经转置过的元素又被转置回去。

import java.util.Scanner;

public class homework2 {
    public static void main(String[] args) {
        int[][] arr=new int[3][3];
        Scanner sc=new Scanner(System.in);
        int temp=0;
        System.out.println("获取3*3的矩阵");
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                arr[i][j]=sc.nextInt();
            }
        }
        sc.close();
        System.out.println("转置3*3的矩阵");
        for (int i = 0; i < 3; i++) {
            for (int j = i; j < 3; j++) {
                temp=arr[i][j];
                arr[i][j]=arr[j][i];
                arr[j][i]=temp;
            }
        }
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                System.out.print(arr[i][j]+" ");
            }
            System.out.println();
        }
    }
}

2、开辟新数组
注意循环条件，i和j都从0开始，否则arr2数组中会有元素没有被赋值。

import java.util.Scanner;

public class homework2 {
    public static void main(String[] args) {
        int[][] arr1=new int[3][3];
        int[][] arr2=new int[3][3];
        Scanner sc=new Scanner(System.in);
        int temp=0;
        System.out.println("获取3*3的矩阵");
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                arr1[i][j]=sc.nextInt();
            }
        }
        sc.close();
        System.out.println("转置3*3的矩阵");
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                arr2[j][i]=arr1[i][j];
            }
        }
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                System.out.print(arr2[i][j]+" ");
            }
            System.out.println();
        }
    }
}