Error in code to find the factorial of a number entered by a user

Question

public static int Factorial(int num) {
    int factorial = 1;
    int num = Integer.parseInt(txtFactorial.getText());

    for (int i = 1; i <= num; i++) {
        factorial = factorial * 1;
    }

    return factorial;
}

The code above is a code I'm trying to put in a subroutine to find the factorial of a number entered by a user and display it in a JLabel. The problem is that it is showing an error with the int num = Integer.parseInt(txtFactorial.getText()); code. This piece of code gets the entry of the user and stores it into the variable num for it to be later used to find the factorial.

Answer 1

You should change your calculation.

public static int Factorial(int num)
{
    int factorial = 1;
    // delete this line int num = Integer.parseInt(txtFactorial.getText());    
    for (int i = 1; i<=num; i++)
    {
        factorial = factorial * i;
    }    
    return factorial;
}

And use the function like this:

ResultLabel.setText(string.valueOf(Factorial(Integer.parseInt(txtFactorial.getText()))));