如何用Java实现矩阵运算 Java矩阵加减乘功能实现

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

    // 构造函数
    public Matrix(double[][] data) {
        if (data == null || data.length == 0 || data[0].length == 0) {
            throw new IllegalArgumentException("矩阵数据不能为空。");
        }
        this.rows = data.length;
        this.cols = data[0].length;
        this.data = new double[rows][cols];
        // 深度拷贝，避免外部修改影响内部数据
        for (int i = 0; i < rows; i++) {
            if (data[i].length != cols) {
                throw new IllegalArgumentException("矩阵每行的列数必须一致。");
            }
            System.arraycopy(data[i], 0, this.data[i], 0, cols);
        }
    }

    public int getRows() {
        return rows;
    }

    public int getCols() {
        return cols;
    }

    // 矩阵加法
    public Matrix add(Matrix other) {
        if (this.rows != other.rows || this.cols != other.cols) {
            throw new IllegalArgumentException("矩阵相加要求维度完全一致。");
        }

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

    // 矩阵减法
    public Matrix subtract(Matrix other) {
        if (this.rows != other.rows || this.cols != other.cols) {
            throw new IllegalArgumentException("矩阵相减要求维度完全一致。");
        }

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

    // 矩阵乘法
    public Matrix multiply(Matrix other) {
        // 矩阵A的列数必须等于矩阵B的行数
        if (this.cols != other.rows) {
            throw new IllegalArgumentException("矩阵乘法要求第一个矩阵的列数等于第二个矩阵的行数。");
        }

        double[][] resultData = new double[this.rows][other.cols];
        for (int i = 0; i < this.rows; i++) { // 结果矩阵的行
            for (int j = 0; j < other.cols; j++) { // 结果矩阵的列
                double sum = 0;
                for (int k = 0; k < this.cols; k++) { // 遍历第一个矩阵的列和第二个矩阵的行
                    sum += this.data[i][k] * other.data[k][j];
                }
                resultData[i][j] = sum;
            }
        }
        return new Matrix(resultData);
    }

    // 打印矩阵
    public void print() {
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                System.out.printf("%8.2f ", data[i][j]);
            }
            System.out.println();
        }
    }

    // 示例用法
    public static void main(String[] args) {
        System.out.println("--- 矩阵A ---");
        double[][] dataA = {{1.0, 2.0, 3.0}, {4.0, 5.0, 6.0}};
        Matrix A = new Matrix(dataA);
        A.print();

        System.out.println("\n--- 矩阵B ---");
        double[][] dataB = {{7.0, 8.0, 9.0}, {10.0, 11.0, 12.0}};
        Matrix B = new Matrix(dataB);
        B.print();

        System.out.println("\n--- 矩阵C (用于乘法) ---");
        double[][] dataC = {{1.0, 2.0}, {3.0, 4.0}, {5.0, 6.0}};
        Matrix C = new Matrix(dataC);
        C.print();

        try {
            System.out.println("\n--- A + B ---");
            Matrix sum = A.add(B);
            sum.print();

            System.out.println("\n--- A - B ---");
            Matrix diff = A.subtract(B);
            diff.print();

            System.out.println("\n--- A * C ---"); // (2x3) * (3x2) -> (2x2)
            Matrix product = A.multiply(C);
            product.print();

            // 尝试非法操作
            System.out.println("\n--- 尝试 B * A (非法操作) ---"); // (2x3) * (2x3) -> 维度不匹配
            B.multiply(A); // 这行会抛出异常
        } catch (IllegalArgumentException e) {
            System.err.println("操作失败: " + e.getMessage());
        }
    }
}

// 以加法为例
public Matrix add(Matrix other) {
    if (this.rows != other.rows || this.cols != other.cols) {
        // 抛出IllegalArgumentException是一个非常Java惯用的处理方式
        throw new IllegalArgumentException("矩阵相加要求维度完全一致。");
    }
    // ... 执行加法逻辑
}