Answer:
In the output of the given piece of code, the following lines are printed on the output screen:
There is a NullPointerException. Everything ran fine.
Explanation:
In the given code
class Student {
public void talk(){} }
This is a Student class which has a function talk()
The following is the Test class
public class Test{
public static void main(String args[])
{ Student t = null; try { t.talk(); }
catch(NullPointerException e)
{ System.out.print("There is a NullPointerException. ");
} catch(Exception e)
{ System.out.print("There is an Exception. "); }
System.out.print("Everything ran fine. "); } }
The above chunk of code creates a Student class object named t which is set to null. A null value is assigned to "t" to indicate that it points to nothing.
In the program a method talk() is called on a null reference. This results in NullPointerException. This is a run time exception. Since no object is created so compiler will not identify this error and this error comes in run time.
The try statement defines a code chunk that is to be tested in case of errors when the code chunk is execute. This is basically used for exception or error handling. The catch statement defines a code chunk (one or two lines of code) that executes if an error occurs in try part (block of code).
Sometimes it is needed to create a reference of the object even before creating an object and this has to be initialized or assigned a value. So null is assigned to such an object reference.
If the talk() method is intended to do something to the object t, which points to nothing, then try throws NullPointerException to indicate this error.
Since the program attempts to use an object reference that contains a null value , so when the program is executed, the try part throws NullPointerException and catch part is executed to indicate this exception. The catch part that executes contains the following statement:
{ System.out.print("There is a NullPointerException. ");
So this message is printed at output screen followed by this statement System.out.print("Everything ran fine. "); } } message. The second catch will not execute as there is no other error in the program except for the NullPointerException. So the output is:
There is a NullPointerException. Everything ran fine.
