answer 19)

4) compilation and output of either "vandaleur", "vandaleur 0", "vandaleur 0 1" "vandaleur 0 1 2" or "vandaleur 0 1 2 3"

if that seems a vauge answer it is because you cannot be certain of the system that the underlying os uses for allocating cycles for a thread. the chances are that once the thread has been spun off in the call to start in the method piggy the main method will run to completion and the value of sname will still be vandeluer before the thread modifies it. you cannot be certain of this though.

answer 20)

3) one button occupying the entire frame saying bye

the default layout manager for a frame is a border layout. if directions are not given (ie north, south, east or west), any button will simply go in the centre and occupy all the space. an additional button will simply be placed over the previous button. what you would probably want in a real example is to set up a flow layout as in

setlayout(new flowlayout()); 

which would allow the buttons to both appear side by side, given the appropriate font and size.
applets and panels have a default flowlayout manager

answer 21)

1,2

value for i=1 value for j=1
value for i=2 value for j=1
 

the statement continue outer causes the code to jump to the label outer and the for loop increments to the next number.

answer 22)

4) runtime error, an exception will be thrown

a call to wait/notify must be within synchronized code. with jdk1.2 this code throws the error message

java.lang.illegalmonitorstateexception: current thread not owner
        at java.lang.object.wait(native method)
        at java.lang.object.wait(object.java:424)
        at dsross.notwait(compiled code)
        at dsross.run(agg.java:21)

answer 23)

2,3

options 1, & 4 will not compile as they attempt to throw exceptions not declared in the base class. because options 2 and 3 take a parameter of type long they represent overloading not overriding and there is no such limitations on overloaded methods.