In a previous post, we had shared a small function that generated random string in Java. It turns out that similar functionality is available from a class in the extremely useful apache commons lang library.

If you are using maven, download the jar using the following dependency:

<dependency>
    <groupId>commons-lang</groupId>
    <artifactId>commons-lang</artifactId>
    <version>20030203.000129</version>
</dependency>

The class we are interested in is RandomStringUtils. Listed below are some functions you may find useful.

• Generate and print a random string of length 5 from all characters available

  
  System.out.println(RandomStringUtils.random(5));

• Generate and print random string of length 10 from upper and lower case alphabets

  
  System.out.println(RandomStringUtils.randomAlphabetic(10));

• Generate and print a random number of length 12

  
  System.out.println(RandomStringUtils.randomNumeric(12));

• Generate and print a random string of length 5 using only a, b, c and d characters

  
  System.out.println(RandomStringUtils.random(10,new char[]{'a','b','c','d'}));