Java数组

实验内容：

1、矩阵的转置：设计一个3X4的矩阵C，输入该矩阵，并且输入该矩阵的转置C’

2、实现两个矩阵的乘积（A*B）和点乘（A.*B），示例如下：

 第一题代码：

package shiyan4.1;

import java.util.Scanner;

public class Matrix_Transpose {
    public static void main(String[] args) {
        transpose();
    }

    public static void transpose () {
        Scanner scanner = new Scanner(System.in);
        int C[][] = new int[3][4];  //创建一个3*4的矩阵

        //利用for循环对二维数组进行赋值
        System.out.println("请输入矩阵的值");
        for (int i = 0; i < C.length; i++) {
            for (int j = 0; j < C[1].length; j++) {
                System.out.print("请输入第"+(i+1)+"行,第"+(j+1)+"列的元素:");
                C[i][j] = scanner.nextInt();
            }
        }

        //对原矩阵进行输出
        System.out.println("矩阵创建成功，原矩阵为:");
        for (int i = 0; i < C.length; i++) {
            for (int j = 0; j < C[1].length; j++) {
                System.out.print(C[i][j] + " ");
            }
            System.out.println();
        }

        //对数组进行转置，创建一个新的数组来存放转置后的值
        int arr[][] = new int[4][3];
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr[0].length; j++) {
                arr[i][j] = C[j][i];
            }
        }

        //对转置后的矩阵进行输出
        System.out.println("矩阵转置成功，转置之后矩阵为:");
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr[0].length; j++) {
                System.out.print(arr[i][j]+" ");
            }
            System.out.println();
        }
    }
}

 第二题代码：

package Shiyan4.1;

import java.util.Scanner;
public class Matrix_Mul {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入矩阵的行数(列数):");
        int num1 = scanner.nextInt();
        int arr1[][] = creatMatrix(num1);
        int arr2[][] = creatMatrix(num1);
        dot_Mul(arr1,arr2);
        cross_Mul(arr1,arr2);
    }

    public static void cross_Mul (int a[][],int b[][]) {
        int c [][] = new int[a.length][b.length];   //用来承接两个矩阵的叉乘结果
        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a.length; j++) {
                int sum = 0;
                for (int k = 0; k < a.length; k++) {   //用来计算新的矩阵的结果
                    sum = sum + a[i][k]*b[k][j];
                }
                c[i][j] = sum;
            }
        }

        System.out.println("叉乘结果为:");
        for (int i = 0; i < c.length; i++) {
            for (int j = 0; j < c[1].length; j++) {
                System.out.print(c[i][j] + " ");
            }
            System.out.println();
        }
    }

    public static void dot_Mul (int a[][],int b[][]) {
        int c[][] = new int[a.length][b.length];    //用来承接两个矩阵的点乘结果
        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a.length; j++) {
                c[i][j] = a[i][j] * b[i][j];
            }
        }
        System.out.println("点乘结果为:");
        for (int i = 0; i < c.length; i++) {
            for (int j = 0; j < c[1].length; j++) {
                System.out.print(c[i][j] + " ");
            }
            System.out.println();
        }
    }
    
    public static int[][] creatMatrix (int a) {
        Scanner scanner = new Scanner(System.in);
        int arr[][] = new int[a][a];
        System.out.println("请输入矩阵的值");
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr[1].length; j++) {
                System.out.print("请输入第"+(i+1)+"行,第"+(j+1)+"列的元素:");
                arr[i][j] = scanner.nextInt();
            }
        }
        return arr;
    }
}

 结果示例：略