title: What does regex pattern "[\\P{L}]+" mean in Java?
body: <p>Code:</p>
  
  <pre><code>Arrays.asList("AAAA DDDD, DDDD".split("[\\P{L}]+")).forEach(System.out::println);
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>AAAA
  DDDD
  DDDD
  </code></pre>
  
  <p>Please notice it's <code>P{L}</code> instead of <code>p{L}</code>(which means letters). I googled it but find nothing. So could any one give me some hint about that?</p>