Array instantiation of unknown type in class

I'm trying to make my own Matrix class in Java. What I want is to specify the type (float, long, int ...) and size M*N of the Matrix when creating it.

In order to do that, I created the class the following way: public class Matrix<T extends Number> { ...

The problem is that when creating the Array this.m = new T[M][N];, an error occurs saying type parameter 'T' cannot be instantiated directly, I'm guessing because different types take different sizes in the memory.

The only way I could get around this was to do: this.m = (T[][]) new Number[M][N]; But I have no idea if this is a good idea, or if there is a better way to do it.

Here is the complete code:

public class Matrix<T extends Number> {

    /**
     * M represents the Matrix' number of rows.
     * N represents the Matrix' number of columns.
     */
    final private int M, N;

    /**
     * Matrix value.
     */
    private T[][] m;

    /**
     * Create a new Matrix instance.
     *
     * @param M Number of rows
     * @param N Number of columns
     */
    public Matrix(final int M, final int N) {
        this.M = M;
        this.N = N;

        this.m = (T[][]) new Number[M][N];
    }

}

Thank you for any help or clarification on this.