making an exception in java

October 7, 2023

I am creating a matrix class in java, and the following is the method for adding two matrices.

public MyMatrix addMatrix(MyMatrix matB) {
        // if (myR != matB.myR || myC != matB.myC) throw an exception
        MyMatrix res = new MyMatrix("", myR, myC, 0.0);
        for (int i = 0; i < myR; i++) {
            for (int j = 0; j < myC; j++) {
                res.myElements[i][j] = myElements[i][j] + matB.myElements[i][j];
            }
        }
        return res;
}

myR is the number of rows and myC is the number of columns in the MyMatrix class.
I want to throw an exception if the number of rows or columns of two matrices are different.
How can I throw an exception in the simplest way possible, without having to create a custom exception or anything else?

I tried
if (myR != matB.myR || myC != matB.myC) throw new Exception();
but it didn’t work. Specifically, it is giving the error "main" java.lang.Error: Unresolved compilation problem: Unhandled exception type Exception".

>Solution :

use : IllegalArgumentException is a Runtime exception

public MyMatrix addMatrix(MyMatrix matB) {
    if (myR != matB.myR || myC != matB.myC) {
        throw new IllegalArgumentException("Matrices must have the same number of rows and columns to be added.");
    }
    MyMatrix res = new MyMatrix("", myR, myC, 0.0);
    for (int i = 0; i < myR; i++) {
        for (int j = 0; j < myC; j++) {
            res.myElements[i][j] = myElements[i][j] + matB.myElements[i][j];
        }
    }
    return res;
}