Where is array's length property defined?

Question

We can determine the length of an ArrayList using its public method size(), like

ArrayList arr = new ArrayL         


        

Answer 1

It's "special" basically, with its own bytecode instruction: arraylength. So this method:

public static void main(String[] args) {
    int x = args.length;
}

is compiled into bytecode like this:

public static void main(java.lang.String[]);
  Code:
   0:   aload_0
   1:   arraylength
   2:   istore_1
   3:   return

So it's not accessed as if it were a normal field. Indeed, if you try to get it as if it were a normal field, like this, it fails:

// Fails...
Field field = args.getClass().getField("length");
System.out.println(field.get(args));

So unfortunately, the JLS description of each array type having a public final field length is somewhat misleading :(