title: In java, why I can declare a variable named "a" but not "1" ?
body: <p>Everything is fine when I declare</p>
  
  <pre><code>String a;
  </code></pre>
  
  <p>but it says <strong>Syntax error on token "1", invalid VariableDeclaratorId</strong> when I do this</p>
  
  <pre><code>String 1;
  </code></pre>
  
  <p>Why is that?</p>