title: Why Underscores in Numeric Literals in Java SE 1.7 Rules are different in Octal and Hexadecimal? Isn't Octal literal violating the rule?
body: <p>According to <a href="https://docs.oracle.com/javase/7/docs/technotes/guides/language/underscores-literals.html" rel="nofollow noreferrer">oracle doc</a> underscores cannot be put at the beginning of a number which is just fine. But when it comes to Octal Number we can put underscores at the beginning. Isn't it weird?</p>
  
  <pre><code>int x1 = 0x_52;            // Invalid; cannot put underscores at the beginning of a number
  int x2 = 0_52;             // OK (octal literal)
  </code></pre>