title: Why can't Java variable names start with a number?
body: <p>In Java, variable names start with a letter, currency character (<code>$</code>) etc. but not with number, <code>:</code>, or <code>.</code> </p>
  
  <p>Simple question: why is that? </p>
  
  <p>Why doesn't the compiler allow to have variable declarations such as </p>
  
  <pre><code>int 7dfs;
  </code></pre>