title: how to make sure an integer number is unique / not repeated
body: <p>program is where users enter their details and they are searched by their social security numbers</p>
  <p>i have the program running but i can enter the same social secirty number over and over</p>
  <p>how can i make sure that users making input enters a unique number??</p>
  <pre><code>Scanner keyboardIn = new Scanner(System.in);
        
        //Create objects of FileWriter and PrintWriter classes
        FileWriter PersonFile = new FileWriter(&quot;persons.txt&quot;);
        PrintWriter pw = new PrintWriter(PersonFile);
  
  int PPSNumber
  
  System.out.print(&quot;Enter PPS Number:&quot;);
           PPSNumber = keyboardIn.nextInt()
  
  pw.println(&quot;PPS Number: &quot; +PPSNumber+ &quot; &quot;); 
  </code></pre>
  <p>Thank you all</p>