Question

public static GetRandomFunc() {
    switch((int)(Math.random()*NUM_FUNCTIONS)  {
        case 0:
            functionA();
            break;
        case 1:
            functionB();
            break;
        case 2:
            functionC();
            break;
          //  ...
    }
}

I want to call GetRandomFunc() in main randomly until each function has been called once and then it ends. How do I make sure a function would be called once only, and if all has been called, it prints out System.out.println(“All done”)

Answer 1

create a list containing 0,1 and 2. shuffle it and iterate over it to call each function once but in random order.

List<Integer> integers = Arrays.asList(0,1,2);
Collections.shuffle(integers)
for (Integer i: integers){
   GetRandomFunc(i)
}

and your function will be

public static GetRandomFunc(int index) {
    switch(index)  {
        case 0:
            functionA();
            break;
        case 1:
            functionB();
            break;
        case 2:
            functionC();
            break;
          //  ...
    }
}