Calling Java Constructors with this()

The things I don’t know about Java… could fill a book. Here’s a new one, from the Hadoop sources:

public ArrayWritable(Class valueClass) {
    // ...

public ArrayWritable(Class valueClass, Writable[] values) {
  this.values = values;

The second constructor uses the syntax this(arg) to call a different constructor, then follows with initialization code of its own. I had no idea you could do that.