Question about making Random Numbers in Java?

Question

I'm making a number guessing game for a school project. I need my "secret number" to be a number from 1 - 100 and rather than hard coding in the number I wanted to make a random number but I don't know how. Any help?

McFate · Accepted Answer

Math.random() returns a random number that is between 0 and 1 (greater than or equal to zero, strictly less than 1).

If you want X different integers, you multiply Math.random() times X, and truncate it to an integer.  So...

(int) (Math.random() * 100)

... is a number from 0 to 99.  Add 1 to that, and you get a number between 1 and 100, inclusive:

(int) (Math.random() * 100) + 1

@M

modulo_function · Answer

If you want an int between 1 and 100, inclusive then use the 
Random 
class.

import java.util.Random;

Random randObj = new Random(); // the object
int randNum = randObj.nextInt(100) + 1;

Saajan · Answer

import java.util.Random;

/** Generate 10 random integers in the range 0..99. */
public final class RandomInteger {
  
  public static final void main(String... aArgs){
    log("Generating 10 random integers in range 0..99.");
    
    //note a single Random object is reused here
    Random randomGenerator = new Random();
    for (int idx = 1; idx <= 10; ++idx){
      int randomInt = randomGenerator.nextInt(100);
      log("Generated : " + randomInt);
    }
    
    log("Done.");
  }
  
  private static void log(String aMessage){
    System.out.println(aMessage);
  }
}

if u want to learn more then go to:
http://www.javapractices.com/topic/TopicAction.do?Id=62

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Question about making Random Numbers in Java?

3 Answers