title: The value of the local variable is not used
body: <p>all of the variables above have the warning in the title. Could you please tell me why that is happening?</p>
  
  <pre><code>public class DataTypes {
      public static void main(String[] argv) {
          // new feature in JDK 7
          int x = 0b1010; // 12
          int y = 0b1010_1010;
          int ssn = 444_12_7691;
          long phone = 408_777_6666L;
          double num = 9_632_401_909.1_0_3;
          String twoLine = "line one\nline two";
      }
  }
  </code></pre>