New to Java

So my initial problem was how to prevent any program I wrote from crashing if I asked the user for an integer, and they entered a double or a string.

Using Keyboard.hasNext() and Keyboard.next() I've been able to elude this problem. But now, if the user inputs two strings, that is: "box cover" or "daffy duck," my prompt asking for input will appear twice.

public static Scanner Keyboard=new Scanner(System.in);
public static double GetDoubleFromUser(){
     double value = -1;
     String invalidentry;
     while(value<0){
          System.out.print("Enter a double: ");
               if(Keyboard.hasNext()){
                    if(Keyboard.hasNextDouble()){
                         value=Keyboard.nextDouble;
                         return value;
                    }else {
                         invalidentry=Keyboard.next();
                    }
               }
         }
}

So the output would appear:

Enter a double: box box
Enter a double: Enter a double:

This has been bugging me for awhile, so any help would be greatly appreciated. I kind of understand the idea of Strings being broken into tokens, but I have no idea how to fix it.