Not working

help me please :(



import java.util.Scanner;

public class FractionTester {

public static void main(String[] args) {
MixedFraction operand1, operand2;

operand1 = enterFractionValue("fraction 1: ");
operand2 = enterFractionValue("fraction 2: ");

// place code below

}


private static MixedFraction enterFractionValue(String operand) {
Scanner keyboard = new Scanner(System.in);
System.out.println("Form of " + operand);
System.out.println(" (a) Fraction: whole value");
System.out.println(" (b) Fraction: with numerator and denominator");
System.out.println(" (c) Mixed Fraction");
char choice;
do {
System.out.println("Enter choice: ");
choice = Character.toLowerCase(keyboard.nextLine().charAt(0 ));
} while (choice != 'a' && choice != 'b' && choice != 'c');
System.out.println();

MixedFraction f;
switch(choice){
case 'a':
System.out.print("Enter the whole value: ");
int whole = keyboard.nextInt();
f = new MixedFraction(whole,0,1);
break;
case 'b':
f = new MixedFraction(0,inputRegularFraction(keyboard));
break;
default:
int w;
do {
System.out.print("Enter whole part: ");
w = Integer.parseInt(keyboard.nextLine());
} while (w == 0);
f = inputRegularFraction(keyboard);
return new MixedFraction(w,f);
}
return f;
}

private static Fraction inputRegularFraction(Scanner kb){
System.out.print("Enter numerator: ");
int n = Integer.parseInt(kb.nextLine());
int d;
do {
System.out.println("Enter denominator: ");
d = Integer.parseInt(kb.nextLine());
} while (d == 0);
return new Fraction(n,d);
}

}