似乎无法弄清楚为什么我的循环不会进展

Question

I can't seem to figure out why my for loop is not working. I have been on the for about an hour now and the closest I have come is this. I'm trying to find out how many McNuggets you can buy using the 6, 9, and 20 packs. All I need dopeChecker(x) to do is return a true or a false. I haven't implemented check the next number yet because it wont even find that a 6 pack can be bought yet. I know it's in the loop somewhere but I just can't find out where. This is form the MIT open course ware problem 2. I don't know if you guys have seen it but I'm just letting you know this is where I'm getting my info.

int x = 0, y = 0, z = 0;// These will the the pack of McNuggets that we can buy.
int testFor = 0; //This will be the number of McNuggets we are looking for.
int matches = 0; //This will be the number of consecutive matches we will be looking for.

public void dopeEquation(){

    while (matches < 6){//It's 6 Because that is the smallest order of nuggets we can buy.

        //Looking for smaller nuggets then we can buy would not make sense. 
        while (testFor < 6){
            testFor++;
        }

        if (dopeChecker(testFor)){
            matches++;

        } else{
            matches = 0;
            System.out.println(x + "," + y +"," + z +"," + testFor + "," + matches);
        }

    }
}

private boolean dopeChecker(int testFor){

    for (  x = 0 ; x*6 <= testFor;  x++){
        for ( y = 0 ; y*9 <= testFor;  y++){
            for (z = 0 ; z*20 <= testFor;){
                System.out.println(x + "," + y +"," + z +"," + testFor + "," + matches);

                if (x*6 + y*9 + z*20 == testFor){
                    matches++;
                    System.out.println("match");
                    return true;
                }else{
                    System.out.println("no match");
                }
            }
        }

    }
    return false;

}
}

Answer 1

The z variable is always 0, you're not changing it.

Answer 2

The following is the innermost for loop. I have commented where the problem is. as you can see, z never gets implemented. therefore, the loop will never terminate, as 0 <= testFor, since TestFor >= 6.

        for (z = 0 ; z*20 <= testFor;/* incrementor needed here*/){
            System.out.println(x + "," + y +"," + z +"," + testFor + "," + matches);

            if (x*6 + y*9 + z*20 == testFor){
                matches++;
                System.out.println("match");
                return true;
            }else{
                System.out.println("no match");
            }
        }

Answer 3

Your code goes inside the first while loop:

while (matches < 6){

Then increased testFor to 6 with the following code:

 while (testFor < 6){
            testFor++;
        }

Then goes to dopeChecker:

 dopeChecker(int testFor)

Then insde the 3rd loop, for z:

 for (z = 0 ; z*20 <= testFor;) {
 ...
 }

z is never incremented, so you need to write this as:

 for (z = 0 ; z*20 <= testFor; z++){
}