Java Random : How to return int value with non significative 0

Question

I need to get a random value between 0 and 100 in String format.

I use Random class, but when i cast the result in String, the non significative 0 are not kepped.

 sb.append((rand.nextInt(99)));

Is there a method in StringBuilder or Random for force the result with this 0 ?

What would you expect `Random` to do here? It just returns an `int`, and there's no notion of an `int` having a difference between 1, 01, or 001. I suspect you want to format the integer as a string first, then append that string to the `StringBuilder`. So the next thing to research is "formatting integers as strings in Java". — Jon Skeet, Feb 03 '21 at 08:13
I need to generate a French phone number with 0X YY YY YY YY format. X is between 0 and 7, NN are number between 0 and 99 with significative 0. But with this command, StringBuilder don't add these 0 ... — Broshet, Feb 03 '21 at 08:15
@Broshet I don't really see how that invalidates the answers in the link I mentioned. `sb.append(String.format("%02d", rand.nextInt(99)));` always appends two digits. When the random number is less than 10, it will prepend a `0`. — Ivar, Feb 03 '21 at 08:24
*FYI:* `nextInt(99)` generates a number in range 0-98 *(both inclusive)*, not a number "between 0 and 100", where it is unspecified whether 0 and 100 are considered "between" too. If yes, range would be 0-100, if no range would be 1-99. None of this generates a number in range 0-99, which is what I think you're looking for. — Andreas, Feb 03 '21 at 08:45
That's it: I want get the numbers between 0 and 99 inclusive, i will use range 0-100. Thanks — Broshet, Feb 03 '21 at 12:40

score 3 · Accepted Answer · answered Feb 03 '21 at 08:19

3

You asked: Is there a method in StringBuilder or Random for force the result with this 0 ?

Answer: No. You need to research for String formatting options. One options is String.format().

Example:

String formatted = String.format("%03d", rand.nextInt(99));
sb.append( formatted );

answered Feb 03 '21 at 08:19

Victor Polo De Gyves Montero

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Sure, but this method allways add a 0 even number is greater than 10 ? Should I have to test lenght each time ? (I execute this traitement 4 time in a hurge data) – Broshet Feb 03 '21 at 08:23
1

@Broshet did you actually try to run the code? – Amongalen Feb 03 '21 at 08:24
Yes, the length is 3 – Broshet Feb 03 '21 at 08:25
@Broshet in the question you talk about numbers up to 100 so Victor assumed that there have to be 3 numbers. Just change it to `"%02d"` to get 2 numbers. – Amongalen Feb 03 '21 at 08:26
1

@Broshet Do your research for String.format at google or SO, test the code. If you find errors, you can open a new question with the errors. – Victor Polo De Gyves Montero Feb 03 '21 at 08:27

score 0 · Answer 2 · answered Feb 03 '21 at 08:20

0

You can use String.format:

public class FormatExample {  
    public static void main(String[] args) {         
        int i = 4;
        int j = 44;
        int k = 102;
        String str1 = String.format("%03d", i);  
        String str2 = String.format("%03d", j);  
        String str3 = String.format("%03d", k); 

        System.out.println(str1);  
        System.out.println(str2);  
        System.out.println(str3);  
    }  
}

Prints:

004
044
102

answered Feb 03 '21 at 08:20

don-joe

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Thanks, I misunderstood the syntax. This is what I was looking for. Thank you all for your help. My explanation was ambiguous, it was 2 digits (00 to 99) – Broshet Feb 03 '21 at 08:35

Java Random : How to return int value with non significative 0

2 Answers2