public class PowerMethod {
    double[][] a;
    double tol;
    double[][] initial;
    double eigenValue;
    double eigenVector[][];

    public PowerMethod(double[][] a, double tol, double[][] initial) {
        this.a = a;
        this.tol = tol;
        this.initial = initial;
    }

    public int findErrorTol() {
        return 0;
    }

    public int powerMethod(double[][] a, double[][] initial) {
        return 0;
    } 
}

public class PowerMethod {
    double[][] a;
    double tol;
    double eigenValApprox;
    double eigenVecApprox[][];

    public PowerMethod(double[][] a, double tol, double[][] initial) {
        this.a = a;
        this.tol = tol;
        eigenVecApprox = initial;
    }

    public int findErrorTol() {
        return 0;
    }

    public int powerMethod(double[][] a, double[][] vecApprox) {
        eigenValApprox = vecApprox[0][0];
        eigenVecApprox = (a * vecApprox) / vecApprox[0][0];                 //implement matrix multiplication
    } 
}

Update PowerMethod.java