矩阵相加、相乘，Java实现

第一个类可以扩展成任意Number或其继承类型

public abstract class GenericMatrix<E extends Number> {
    protected abstract E add(E o1,E o2);
    
    protected abstract E multiply(E o1,E o2);
    
    protected abstract E zero();
    
    public E[][] addMatrix(E[][] matrix1,E[][] matrix2){
        if((matrix1.length != matrix2.length) || 
                (matrix1[0].length != matrix2[0].length)) {
            throw new RuntimeException("The matrices do not have the same size ");
        }
        
        E[][] result = (E[][])new Number[matrix1.length][matrix1[0].length];
        
        for(int i = 0;i < result.length;i++)
            for(int j = 0;j < result[i].length;j++) {
                result[i][j] = add(matrix1[i][j],matrix2[i][j]);
            }
        return result;
    }
    
    public E[][] multiplyMatrix(E[][] matrix1,E[][] matrix2){
        if(matrix1[0].length != matrix2.length) {
            throw new RuntimeException("The matrices do not compatible size ");
        }
        
        E[][] result = (E[][])new Number[matrix1.length][matrix2[0].length];
        
        for(int i = 0;i < matrix1.length;i++)
            for(int j = 0;j < matrix2[0].length;j++) {
                result[i][j] = zero();
                for(int k = 0;k < matrix1[0].length;k++) {
                    result[i][j] = add(result[i][j],multiply(matrix1[i][k],matrix2[k][j]));
                }
            }
        
        return result;
    }
    
    public static void printResult(Number[][] m1,Number[][] m2,Number[][] m3,char op) {
        for(int i = 0;i < m1.length;i++) {
            for(int j = 0;j < m1[0].length;j++)
                System.out.print(" "+m1[i][j]);
            
            if(i == m1.length / 2)
                System.out.print(" "+op+" ");
            else
                System.out.print("   ");
            
            for(int j = 0;j < m2.length;j++)
                System.out.print(" "+ m2[i][j]);
            
            if(i == m1.length / 2)
                System.out.print(" = ");
            else
                System.out.print("   ");
            
            for(int j = 0;j < m3.length;j++)
                System.out.print(m3[i][j]+" ");
            
            System.out.print("\n");
        }
    }
}

以下是扩展成Integer类的实例：

public class IntegerMatrix extends GenericMatrix<Integer>{
    @Override
    protected Integer add(Integer o1,Integer o2) {
        return o1 + o2;
    }
    
    @Override
    protected Integer multiply(Integer o1,Integer o2) {
        return o1*o2;
    }
    
    @Override
    protected Integer zero() {
        return 0;
    }
}

实现上面的两个类：

public class TestIntegerMatrix {

    public static void main(String[] args) {
        Integer[][] m1 = new Integer[][] {{1,2,3},{4,5,6},{1,1,1}};
        Integer[][] m2 = new Integer[][] {{1,1,1},{2,2,2},{0,0,0}};
        
        IntegerMatrix im = new IntegerMatrix();
        
        System.out.println("\nm1 + m2 is ");
        GenericMatrix.printResult(m1, m2, im.addMatrix(m1, m2), '+');
        
        System.out.println("\nm1 * m2 is ");
        GenericMatrix.printResult(m1, m2, im.multiplyMatrix(m1, m2), '*');
    }

}