Java/Random numbers

[edit] Java Random Numbers

Java provides one utility class called Random. This class mainly used to generate random numbers. This class is very much useful for an application that selects a winner randomly. This class can also be used to generate random passwords. I mainly use this class for "Forgot your Password" section.

The below example will generate random number ten times and every time it will generate a different number between 0 and 50.

import java.util.Random;
 
public class RandomNumberExample {
 
  public static void main(String[] args) {
 
    Random randomNumber = new Random( System.currentTimeMillis() );
 
    for (int i = 0; i < 10; i++) {
      System.out.println(randomNumber.nextInt(50));
    }
 
  }
 
}

[edit] How to create Random passwords

If you are looking for an example to generate a random password then below example will help you. In this example the word range will be 0-9, A-Z and a-z. Since we want the combination of this characters, we have put a condition where we are checking for the integer value to be in range of 48 - 57 or 65 - 90 or 97 - 122. These integer values represents the ASCII values for the above word range.

Please refer the ASCII chart.

import java.util.Random;
 
public class RandomPassword {
 
  public static void main(String[] args) {
 
    Random randomNumber = new Random();
 
    char password[] = new char[15];
 
    for (int i = 0; i < 15;) {
 
      int value = randomNumber.nextInt(125);
      System.out.println(value);
      if ((value >= 48 && value <= 57) || (value >= 65 && value <= 90)
          || (value >= 97 && value <= 122)) {
 
        password[i] = (char) value;
        i++;
      }
    }
    System.out.println("Your password is " + new String(password));
  }
}