title: How so I concatenate int values without adding them? (Java)
body: <p>New at coding, and I'm running some basic exercises to get used to the language.
  In this exercise I'm trying to generate a phone number with the following restrictions:</p>
  
  <ol>
  <li>1st 3 digits cannot contain an 8 or 9</li>
  <li>2nd set of 3 digits cannot be higher than 742</li>
  </ol>
  
  <p>I've seen suggestions to add an empty string (which I have), but I don't understand why that works. For now, I'll be sticking with the following, even though I don't fully understand why it works.</p>
  
  <pre><code>num1 = rand.nextInt(7) + 1;
  num2 = rand.nextInt(7) + 1;
  num3 = rand.nextInt(7) + 1;
  num4 = rand.nextInt(643) + 100;
  num5 = rand.nextInt(1001) + 1000;
  
  String number = "" + num1 + num2 + num3 + "-" + num4 + "-" + num5;
  
  System.out.print("Your assigned phone number is: " + number);
  </code></pre>
  
  <p><strong>EDIT: NEW CODE INCLUDES sb.append</strong></p>
  
  <pre><code>    StringBuilder sb = new StringBuilder();
  
      int num1, num2, num3, num4, num5;
  
      num1 = rand.nextInt(7) + 1;
      num2 = rand.nextInt(7) + 1;
      num3 = rand.nextInt(7) + 1;
      num4 = rand.nextInt(643) + 100;
      num5 = rand.nextInt(1001) + 1000;
  
      sb.append(num1);
      sb.append(num2);
      sb.append(num3);
      sb.append("-");
      sb.append(num4);
      sb.append("-");
      sb.append(num5);
  
      //String number = "" + num1 + num2 + num3 + "-" + num4 + "-" + num5;
  
      System.out.print("Your assigned phone number is: " + sb.toString());
  </code></pre>
  
  <p>@Serge 's answer worked for me. Though it does seem to require more coding with all the sb.append calls I have to include. I've yet to learn about the StringBuilder class, but it definitely seems to be helpful. Thank you, everyone.</p>