CODEWITHSUNDEEP
javafunctionprogram-entry-point
user872009
user872009

Reputation: 438

Get Random Functions from Main

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")

Upvotes: 3

Views: 124

Answers (3)

Masood_mj
Masood_mj

Reputation: 1184

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;
          //  ...
    }
}

Upvotes: 5

vektor
vektor

Reputation: 2926

Make a list of the functions and take from it at random. When it's empty, you can be sure you used every function exactly once.

public interface Function { void execute(); }

public static runFunctionsRandomly(List<Function> functions) {
  while (!functions.isEmpty()) {
      int index = Math.random() * functions.size();
      Function f = functions.get(index);
      f.execute();
      functions.remove(index);
  }
}

class ExampleFunction implements Function {
  void execute() {
    System.out.println("Hello world!");
  }
}
...

Upvotes: 3

JB Nizet
JB Nizet

Reputation: 691775

Use a list of Runnables (or of Integers mapping to each function, as you did in your code), shuffle it, then iterate through the list and call each function.

http://docs.oracle.com/javase/6/docs/api/java/util/Collections.html#shuffle%28java.util.List%29

Upvotes: 3

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