OCJP Samples Questions: Exceptions and assertions

OCP Java SE 8 Exam
Sample Questions
Exceptions and Assertions
Hari Kiran & S G Ganesh

Question
Consider the following program:
class ChainedException {
public static void foo() {
try {
throw new ArrayIndexOutOfBoundsException();
} catch(ArrayIndexOutOfBoundsException oob) {
RuntimeException re = new RuntimeException(oob);
re.initCause(oob);
throw re;
}
}
public static void main(String []args) {
try {
foo();
} catch(Exception re) {
System.out.println(re.getClass());
} } }
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When executed this program from
main() by calling foo() method,
prints which of the following?
A. class
java.lang.RuntimeException
B. class
java.lang.IllegalStateException
C. class java.lang.Exception
D. class
java.lang.ArrayIndexOutOfBou
ndsException

Answer
class ChainedException {
public static void foo() {
try {
throw new ArrayIndexOutOfBoundsException();
} catch(ArrayIndexOutOfBoundsException oob) {
RuntimeException re = new RuntimeException(oob);
re.initCause(oob);
throw re;
}
}
try {
foo();
} catch(Exception re) {
System.out.println(re.getClass());
} } }
When executed this program from
main() by calling foo() method,
prints which of the following?
A. class
java.lang.RuntimeException
B. class
java.lang.IllegalStateException
C. class java.lang.Exception
D. class
java.lang.ArrayIndexOutOfBoun
dsException

Explanation
B. class java.lang.IllegalStateException
In the expression new RuntimeException(oob);, the
exception object oob is already chained to the
RuntimeException object. The method initCause() cannot be
called on an exception object that already has an exception
object chained during the constructor call.
Hence, the call re.initCause(oob); results in initCause()
throwing an IllegalStateException .

Question
class EHBehavior {
try {
int i = 10/0; // LINE A
System.out.print("after throw -> ");
} catch(ArithmeticException ae) {
System.out.print("in catch -> ");
return;
} finally {
System.out.print("in finally -> ");
}
System.out.print("after everything");
} }
Which one of the following options best describes the behaviour of this program?
A. The program prints the following: in catch -> in finally -> after everything
B. The program prints the following: after throw -> in catch -> in finally -> after
everything
C. The program prints the following: in catch -> after everything
D. The program prints the following: in catch -> in finally ->

Answer
class EHBehavior {
try {
int i = 10/0; // LINE A
System.out.print("after throw -> ");
} catch(ArithmeticException ae) {
System.out.print("in catch -> ");
return;
} finally {
System.out.print("in finally -> ");
}
System.out.print("after everything");
} }
Which one of the following options best describes the behaviour of this program?
A. The program prints the following: in catch -> in finally -> after everything
B. The program prints the following: after throw -> in catch -> in finally -> after
everything
C. The program prints the following: in catch -> after everything
D. The program prints the following: in catch -> in finally ->

Explanation
D . The program prints the following: in catch -> in finally ->
The statement println("after throw -> "); will never be
executed since the line marked with the comment LINE A
throws an exception. The catch handles ArithmeticException ,
so println("in catch -> "); will be executed.
Following that, there is a return statement, so the function
returns. But before the function returns, the finally statement
should be called, hence the statement println("in finally -> ");
will get executed. So, the statement println("after
everything"); will never get executed

Question
import java.util.Scanner;
class AutoCloseableTest {
try (Scanner consoleScanner = new Scanner(System.in)) {
consoleScanner.close(); // CLOSE
consoleScanner.close();
}
}
}
Which one of the following statements is correct?
A. This program terminates normally without throwing any exceptions
B. This program throws an IllegalStateException
C. This program throws an IOException
D. This program throws an AlreadyClosedException

Answer
import java.util.Scanner;
class AutoCloseableTest {
try (Scanner consoleScanner = new Scanner(System.in)) {
consoleScanner.close(); // CLOSE
consoleScanner.close();
}
}
}
Which one of the following statements is correct?
A. This program terminates normally without throwing any exceptions
B. This program throws an IllegalStateException
C. This program throws an IOException
D. This program throws an AlreadyClosedException

Explanation
A . This program terminates normally without throwing any
exceptions
The try-with-resources statement internally expands to call
the close() method in the finally block. If the resource is
explicitly closed in the try block, then calling close()
again does not have any effect. From the description of the
close() method in the AutoCloseable interface: “Closes this
stream and releases any system resources associated with it.
If the stream is already closed, then invoking this method has
no effect.”

Question
class AssertionFailure {
try {
assert false;
} catch(RuntimeException re) {
System.out.println("RuntimeException");
} catch(Exception e) {
System.out.println("Exception");
} catch(Error e) { // LINE A
System.out.println("Error" + e);
} catch(Throwable t) {
System.out.println("Throwable");
}
}
}
This program is invoked from the
command line as follows:
java AssertionFailure
Choose one of the following options
describes the behaviour of this
program:
A. Prints "RuntimeException" in
console
B. Prints "Exception"
C. Prints "Error"
D. Prints "Throwable"
E. Does not print any output on
console

Answer
class AssertionFailure {
try {
assert false;
} catch(RuntimeException re) {
System.out.println("RuntimeException");
} catch(Exception e) {
System.out.println("Exception");
} catch(Error e) { // LINE A
System.out.println("Error" + e);
} catch(Throwable t) {
System.out.println("Throwable");
}
}
}
This program is invoked from the
command line as follows:
java AssertionFailure
Choose one of the following options
describes the behaviour of this
program:
A. Prints "RuntimeException" in
console
B. Prints "Exception"
C. Prints "Error"
D. Prints "Throwable"
E. Does not print any output on
console

Explanation
E . Does not print any output on the console
By default, assertions are disabled. If -ea (or the -
enableassertions option to enable assertions), then the
program would have printed "Error" since the exception
thrown in the case of assertion failure is
java.lang.AssertionError , which is derived from
the Error class

Question
Consider the following class hierarchy from the package
javax.security.auth.login and answer the questions.
Which of the following handlers that makes use of multi-catch exception handler
feature will compile without errors?
A. catch (AccountException | LoginException exception)
B. catch (AccountException | AccountExpiredException exception)
C. catch (AccountExpiredException | AccountNotFoundException exception)
D. catch (AccountExpiredException exception1 | AccountNotFoundException
exception2)

Answer
Consider the following class hierarchy from the package
javax.security.auth.login and answer the questions.
Which of the following handlers that makes use of multi-catch exception handler
feature will compile without errors?
A. catch (AccountException | LoginException exception)
B. catch (AccountException | AccountExpiredException exception)
C. catch (AccountExpiredException | AccountNotFoundException exception)
D. catch (AccountExpiredException exception1 | AccountNotFoundException
exception2)

Explanation
C . catch (A ccountExpiredException | A
ccountNotFoundException exception)
For A and B, the base type handler is provided with the
derived type handler, hence the multi-catch is incorrect.
For D, the exception name exception1 is redundant and will
result in a syntax error. C is the correct option and this will
compile fine without errors.

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OCJP Samples Questions: Exceptions and assertions

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