----- Original Message -----
From: "Nicholas R. Rinard" <email@hidden>
To: "Java Listserv java-dev" <email@hidden>
Sent: Thursday, April 14, 2005 8:27 PM
Subject: Re: question about null pointers
> Alas, we may never know,
if (model.equals(null)) System.out.println("null");
6: putfield #2; //Field model:Ljava/lang/Object;
9: aload_0
10: getfield #2; //Field model:Ljava/lang/Object;
13: aconst_null
14: invokevirtual #3; //Method
java/lang/Object.equals:(Ljava/lang/Object;)Z
17: ifeq 28
20: getstatic #4; //Field java/lang/System.out:Ljava/io/PrintStream;
Invokes a method java/lang/Object.equals:(Ljava/lang/Object;)Z
which can NullPointerException if the first java/lang/Object is null.
if (model == null) System.out.println("null");
5: aconst_null
6: putfield #2; //Field model:Ljava/lang/Object;
9: aload_0
10: getfield #2; //Field model:Ljava/lang/Object;
13: ifnonnull 24
16: getstatic #3; //Field java/lang/System.out:Ljava/io/PrintStream;
Does not invoke a method to NPE.
Impossible as stated or the compiler is broke or doing something very
different or the JVM is broke or doing something very different, either way
it would not be different in a good way.
javap -c
output fwiw.
Mike Hall mikehall at spacestar dot net
http://www.spacestar.net/users/mikehall
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