用Java 编写程序实现对矩阵的加法、减法和乘法运算。

好的，以下是 Java 编写程序实现对矩阵的加法、减法和乘法运算的示例代码：

public class Matrix {
    private int[][] data;
    private int rows;
    private int cols;

    public Matrix(int[][] data) {
        this.data = data;
        this.rows = data.length;
        this.cols = data[0].length;
    }

    public Matrix add(Matrix other) {
        if (this.rows != other.rows || this.cols != other.cols) {
            throw new IllegalArgumentException("Matrices must have the same dimensions");
        }

        int[][] result = new int[rows][cols];
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                result[i][j] = this.data[i][j] + other.data[i][j];
            }
        }

        return new Matrix(result);
    }

    public Matrix subtract(Matrix other) {
        if (this.rows != other.rows || this.cols != other.cols) {
            throw new IllegalArgumentException("Matrices must have the same dimensions");
        }

        int[][] result = new int[rows][cols];
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                result[i][j] = this.data[i][j] - other.data[i][j];
            }
        }

        return new Matrix(result);
    }

    public Matrix multiply(Matrix other) {
        if (this.cols != other.rows) {
            throw new IllegalArgumentException("The number of columns in the first matrix must be equal to the number of rows in the second matrix");
        }

        int[][] result = new int[this.rows][other.cols];
        for (int i = 0; i < this.rows; i++) {
            for (int j = 0; j < other.cols; j++) {
                for (int k = 0; k < this.cols; k++) {
                    result[i][j] += this.data[i][k] * other.data[k][j];
                }
            }
        }

        return new Matrix(result);
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                sb.append(data[i][j]).append(" ");
            }
            sb.append("\n");
        }
        return sb.toString();
    }
}

使用示例：

int[][] data1 = {{1, 2}, {3, 4}};
int[][] data2 = {{5, 6}, {7, 8}};
Matrix matrix1 = new Matrix(data1);
Matrix matrix2 = new Matrix(data2);

// 加法
Matrix sum = matrix1.add(matrix2);
System.out.println("Sum:\n" + sum);

// 减法
Matrix difference = matrix1.subtract(matrix2);
System.out.println("Difference:\n" + difference);

// 乘法
Matrix product = matrix1.multiply(matrix2);
System.out.println("Product:\n" + product);

输出结果：

Sum:
6 8 
10 12 

Difference:
-4 -4 
-4 -4 

Product:
19 22 
43 50