How to use JDI handle event, need you help!~

Question

Hi,
In our recent project, I need listen some event such as ClassPrepareEvent, MethodEntryEvent using JDI and handle it. I am trying to mend the TTY and let it
do something simple when MethodEntryEvent occur.
I just add a print line in the method methodEntryEvent in TTY.java. But I noticed that this method is not invocated after I input "run" commond. I don't konw why? And how can I listen this event? And when the methodEntryEvent method in TTY will be invocated?
Anyone can help me ???
Thank you!!!
PS: methodEntryEvent method is post as follow:
public void methodEntryEvent(MethodEntryEvent me) {
Thread.yield(); // fetch output
//notice:
//i want print this sentens when every method entry.
System.out.println("Method Entry:");
StringBuffer buffer = new StringBuffer("\nMethod Entered: ");
buffer.append(me.method().declaringType().name());
buffer.append(".");
buffer.append(me.method().name());
buffer.append(" ");
out.print(buffer.toString());
otherEvent(me);
Duan
SJTU

Answer 1

You must enable a MethodEntryRequest before any MethodEntryEvent will
be reported.
In the jdb/TTY reference debugger, use the 'trace methods [thread]'
and 'untrace methods [thread]' commands to turn tracing on or off
for method entry and exit.
Once you request MethodEntry/Exit notification, then the methodEntryEvent
handler in TTY.java will be called and you will see the println() you
added to the code.