Why does my method sometimes print multiple lines?

Question

So I Have this method

public int sumMathRandomAndSystemTime(){

    n = 1 + ((int) (Math.random() * 10)+ 
            (int) (System.currentTimeMillis() % 10));

    if(n > 10){
        sumMathRandomAndSystemTime();
    }
    System.out.println(n);
    return n;

}

All I want is to print one random number (n) between 1 and 10 once. But for some reason, when I call the method it does print a random number, but some times only once, other times it prints the number like 10 times, 5 times, etc. Why is this happening?

Here's an example of my output

ok, but how do i get rid of the multiple lines of print? Any suggestions? — Jorge Padilla, Nov 07 '17 at 05:37
if you are trying to print when n is bigger than 10. wrap you print method call with else block — SungJin Steve Yoo, Nov 07 '17 at 05:37
Remove the recursive call. It doesn't even do anything (other than printing) — tkausl, Nov 07 '17 at 05:37
I just want to print a random number, which I get from the sum of a Math.Random number and another random number using System time, where the sum has to be between 1 and 10 — Jorge Padilla, Nov 07 '17 at 05:39
Put the word “return” before sumMathRandomAndSystemTime(); — cpp beginner, Nov 07 '17 at 05:44

Adiel Loinger · Answer 1 · 2017-11-07T05:45:26.923

IF the original random number is larger then 10, your code will print multiple lines: one for each recursive call.

You can change your code as following to solve this problem:

public int sumMathRandomAndSystemTime(){

    int n = getRandomNumber();
    System.out.println(n);
    return n;

}

public int getRandomNumber() {
    int n = 1 + ((int) (Math.random() * 10)+
            (int) (System.currentTimeMillis() % 10));

    if(n > 10){
        n = getRandomNumber();
    }
    return n;
}

And in general a much simpler code would be:

public int sumMathRandomAndSystemTime(){
    Random random = new Random();
    int n = random.nextInt(10);
    System.out.println(n);
    return n;
}

score 1 · Answer 2 · answered Nov 07 '17 at 05:53

If you only want to print one random number between 1 and 10, try something like this...

        int n;
        do
        {
          n = 1 + ((int) (Math.random() * 10) + (int) (System.currentTimeMillis() % 10));
        } while(n > 10);

        return n;

gifpif · Answer 3 · 2018-06-30T06:09:31.337

1

Add return statement after sumMathRandomAndSystemTime(); call.

public static int sumMathRandomAndSystemTime(){
    n = 1 + ((int) (Math.random() * 10)+ 
            (int) (System.currentTimeMillis() % 10));
    if(n > 10){
        sumMathRandomAndSystemTime();
        return n;
    }
    System.out.println(n);
    return n;
}

May be this picture can clear the flow.

edited Jun 30 '18 at 06:09

answered Nov 07 '17 at 06:17

gifpif

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Why does my method sometimes print multiple lines?

3 Answers3