Re: Show stack objects/instructions

On 03/27/2011 11:57 PM, [email protected] wrote:
> hi,
>
> is there any posibility to generate/display stack or instructions which added
> elements to stack from actual instruction?
>
> regards

PrintWriter pw = new PrintWriter(System.out);
CheckClassAdapter.verify(new ClassReader(byteArray), true, pw);

with byteArray containing the actual bytecode.

You will get something like the code below:
main([Ljava/lang/String;)V
00000 String . .  :  :     NEW java/lang/Object
00001 String . .  : Object  :     ASTORE 1
00002 String Object .  :  :     ALOAD 1
00003 String Object .  : Object  :     INVOKESPECIAL 
java/lang/Object.<init> ()V
00004 String Object .  :  :     ALOAD 1
00005 String Object .  : Object  :     IFNONNULL L0
00006 String Object .  :  :     GETSTATIC java/lang/System.out : 
Ljava/io/PrintStream;
00007 String Object .  : PrintStream  :     ASTORE 1
00008 String PrintStream .  :  :     LDC "null !"
00009 String PrintStream .  : String  :     ASTORE 2
00010 String PrintStream String  :  :     ALOAD 1
00011 String PrintStream String  : PrintStream  :     ALOAD 2
00012 String PrintStream String  : PrintStream String  :     
INVOKEVIRTUAL java/io/PrintStream.println (Ljava/lang/String;)V
00013 String PrintStream String  :  :    L1
00014 String PrintStream String  :  :     RETURN
00015 String Object .  :  :    L0
00016 String Object .  :  :     GETSTATIC java/lang/System.out : 
Ljava/io/PrintStream;
00017 String Object .  : PrintStream  :     ASTORE 1
00018 String PrintStream .  :  :     LDC "not null !"
00019 String PrintStream .  : String  :     ASTORE 2
00020 String PrintStream String  :  :     ALOAD 1
00021 String PrintStream String  : PrintStream  :     ALOAD 2
00022 String PrintStream String  : PrintStream String  :     
INVOKEVIRTUAL java/io/PrintStream.println (Ljava/lang/String;)V
00023 String PrintStream String  :  :     GOTO L1

To decode it:
   String . . : : NEW java/lang/Object
means:
   String . . : we have 3 locals, the first one contains a String the 
others are uninitialized
   :               empty stack

Rémi

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