Is it possible to get and operate the objects declared in debuggee !?

Question

Hi,
I can get the ObjectReferences of the local variables or fields and get or set their values.
But what I want is to get the real object instance, is it possible ?
for example: I have a class A, and I want to debug it
class A{
StringBuffer sb = new StringBuffer("This is ");
A(){
I can get the objectreference "objref_sb" of sb,
but I wish to get the reference of sb (that's say ref_sb)in class A, such that I can operate ref_sb directly.
i.e. ref_sb.append("test");
How can I do it ?
thanks in advance !

Answer 1

I wish to get the reference of sb (that's say ref_sb)in
class A, such that I can operate ref_sb directly.
i.e. ref_sb.append("test");You would need to evaluate that operation in the debugee VM.
Take a look at the eval <expr> command in jdb.
Something like this would do it:
% cat -n HelloWorld.java
     1  public class HelloWorld {
     2      public static void main(String args[]) {
     3          StringBuffer sb = new StringBuffer();
     4          sb.append("Hello");
     5          System.out.println(sb.toString());
     6      }
     7  }
% jdb HelloWorld
Initializing jdb...
stop at HelloWorld:5Deferring breakpoint HelloWorld:5.
It will be set after the class is loaded.
runrun HelloWorld
>
VM Started: Set deferred breakpoint HelloWorld:5
Breakpoint hit: thread="main", HelloWorld.main(), line=5, bci=15
  5         System.out.println(sb.toString());
main[1] eval sb.append(" world")
sb.append(" world") = instance of java.lang.StringBuffer(id=193)
main[1] eval sb.toString()
sb.toString() = "Hello world"
main[1] cont
Hello world
The application exited