title: Making a random string lower case
body: <p>I need to create a string of three random capital letters and three random digits, and output the result, which I have done. 
  Next I need to make this whole string lower case, output the result, then make only the first character upper case and output the result. I've been trying to use <code>substring()</code>, but it isn't compiling and I'm not too sure how to use <code>substring()</code> with random generator. Here is what I have written and it would be great if i could get some help.</p>
  
  <pre><code>import java.util.Random;
  
  public class RandomString
  {
      public static void main(String[] args)
      {  Random generator = new Random();
  
         int randomNumber = generator.nextInt(2);
         char randomChar = (char)('A');
         System.out.print("A random string is " + randomChar);
  
         randomNumber = generator.nextInt(26);
         randomChar = (char)('A' + randomNumber);
         System.out.print(randomChar);
  
         randomNumber = generator.nextInt(26);
         randomChar = (char)('A' + randomNumber);
         System.out.print(randomChar);
  
         randomNumber = generator.nextInt(10);
         System.out.print(randomNumber);
  
         randomNumber = generator.nextInt(10);
         System.out.print(randomNumber);
  
         randomNumber = generator.nextInt(10);
         System.out.println(randomNumber);
  
      }
  }
  </code></pre>