WindowEvent is generated when a window is activated, closed, deactivated, 

deiconfied, iconfied, opened or quit.

Thread t is seeded to currently program, hence when you run the program the thread 

becomes active & code 't.isAlive' returns true.
Output:
$ javac multithreaded_programing.java
$ java multithreaded_programing
true

reverse() method reverses all characters. It returns the reversed object on which it was called.
Output:
$ javac output.java
$ java output
olleH

For the 1st iteration -1 is displayed. The 2nd exception is caught in catch block and 0 

is displayed.
Output:
$ javac exception_handling.java
$ java exception_handling
-10

AdjustmentEvent is generated when a scroll bar is manipulated.

The output of program is Thread[main,5,main], Since we have not explicitly named the 

thread they are named by the group to they belong i:e main method. Hence they are 

named ‘main’.

Output:
$ javac multithreaded_programing.java
$ java multithreaded_programing
Thread[main,5,main]

Value of variable sum is printed outside of try block, sum is declared only in try block, 

outside try block it is undefined.
Output:
$ javac exception_handling.java
Exception in thread "main" java.lang.Error: Unresolved compilation problem:
sum cannot be resolved to a variable

EventObject class is a super class of all the events and is defined in java.util package.

The output of program is Thread[main,5,main], in this priority assigned to the thread

is 5. Its the default value.  Since  we have not named  the thread they  are named by 

the group to they belong i:e main method.
Output:
$ javac multithreaded_programing.java
$ java multithreaded_programing
Thread[main,5,main]

length() method is used to obtain length of StringBuffer object, length of "Hello" is 5.
Output:
$ javac output.java
$ java output
5