Java Puzzler

NullVarArgs.java

public class NullVarArgs {

    public static void main(String... args) {

        // 1
        exec(null);

        // 2
        exec((String) null);

        // 3
        final String s = null;
        exec(s);
    }


    private static void exec(String... args) {
        System.out.println(args);
    }
}

Output:

null
[Ljava.lang.String;@5a07e868
[Ljava.lang.String;@76ed5528

// class version 52.0 (52)
// access flags 0x21
public class meh/NullVarArgs {

  // compiled from: NullVarArgs.java

  // access flags 0x1
  public <init>()V
   L0
    LINENUMBER 3 L0
    ALOAD 0
    INVOKESPECIAL java/lang/Object.<init> ()V
    RETURN
   L1
    LOCALVARIABLE this Lmeh/NullVarArgs; L0 L1 0
    MAXSTACK = 1
    MAXLOCALS = 1

  // access flags 0x89
  public static transient varargs main([Ljava/lang/String;)V
   L0
    LINENUMBER 8 L0
    ACONST_NULL
    INVOKESTATIC meh/NullVarArgs.exec ([Ljava/lang/String;)V
   L1
    LINENUMBER 11 L1
    ICONST_1
    ANEWARRAY java/lang/String
    DUP
    ICONST_0
    ACONST_NULL
    CHECKCAST java/lang/String
    AASTORE
    INVOKESTATIC meh/NullVarArgs.exec ([Ljava/lang/String;)V
   L2
    LINENUMBER 14 L2
    ACONST_NULL
    ASTORE 1
   L3
    LINENUMBER 15 L3
    ICONST_1
    ANEWARRAY java/lang/String
    DUP
    ICONST_0
    ALOAD 1
    AASTORE
    INVOKESTATIC meh/NullVarArgs.exec ([Ljava/lang/String;)V
   L4
    LINENUMBER 16 L4
    RETURN
   L5
    LOCALVARIABLE args [Ljava/lang/String; L0 L5 0
    LOCALVARIABLE s Ljava/lang/String; L3 L5 1
    MAXSTACK = 4
    MAXLOCALS = 2

  // access flags 0x8A
  private static transient varargs exec([Ljava/lang/String;)V
   L0
    LINENUMBER 20 L0
    GETSTATIC java/lang/System.out : Ljava/io/PrintStream;
    ALOAD 0
    INVOKEVIRTUAL java/io/PrintStream.println (Ljava/lang/Object;)V
   L1
    LINENUMBER 21 L1
    RETURN
   L2
    LOCALVARIABLE args [Ljava/lang/String; L0 L2 0
    MAXSTACK = 2
    MAXLOCALS = 1
}

Warning:(8, 14) java: non-varargs call of varargs method with inexact argument type for last parameter;
cast to java.lang.String for a varargs call
cast to java.lang.String[] for a non-varargs call and to suppress this warning