Here are my made up questions for section 2. Please comment or point out any poorly worded questions.
1 What will the following code output?
1 Compilation fails
2 An exception occurs at runtime
3 12false
4 true
5 12true
6 5true
2 Which two of the following lines will fail to compile?
1) int x = 1; switch (x) {}
2) double d = 2; switch(d) {}
3) int [] a = {1,2,3}; switch (a.length) {}
4) char c = 'b'; switch (c) {}
5) Integer i = new Integer(2); switch (i) {}
6) int z = 2; switch (z*2) {}
3 What will be the output of the following code?
1 Compilation fails
2 An exception occurs at runtime
3 11
4 00
5 1345678910
6 135791111
7 134567899
4 What will be the output of the following code?
1 Compilation fails
2 An exception occurs at runtime
3 0123
4 00
5 01230123
6 0123012301230
7 012301230123
5 Which two of the following statements are false?
1 All exception classes derive from Throwable
2 You can catch multiple types of exceptions with a single catch clause
3 The finally block is ALWAYS executed
4 You need to explicitly handle RuntimeException for code to compile
5 You can throw an exception out of main instead of handling it
6 It is legal to use a try without a catch if you have a finally clause
7 The method printStackTrace() prints the most recent method first
6 If you wish to throw an exception of type MyExcept, what is the proper line to replace // Here
1 throw new MyExcept();
2 throws MyExcept;
3 throw MyExcept();
4 MyExcept.throw;
5 new MyExcept();
6 throw MyExcept;
7 If you compile and run the following program, what will its output be?
1 Compile time error
2 abException in
thread "main" java.lang.ArithmeticException
3 abcInfinity
4 abcd10
5 abe10
6 abd10
7 abe0
8 Consider the following code. What will its output be?
1 Compile time error
2 14
3 144
4 124
5 1404
6 24
9 Which three of the following lines could be legal and appropriate uses of assert?
1 assert count > 0: count++;
2 assert students < 30: students;
3 assert teachers < 20: System.out.print(teachers);
4 assert score > 0;
5 assert true;
6 assert false;
10 Which output is the closest to the real output of the following program if compiled with assertions and run with assertions enabled?
1 Compile error
2 zero Exception in thread "main" java.lang.AssertionError: zero
3 bigger Exception in thread "main" java.lang.AssertionError: bigger
4 zero
5 bigger smaller
6 zero zero Exception in thread "main" java.lang.AssertionError
7 bigger bigger Exception in thread "main" java.lang.AssertionError
11 Which two of the following statements are true?
1 It is often appropriate to use assert false on default cases of switch statements
2
You should use assertions to check values passed in to public methods
3 You should use assert to validate code that should never be reached is not reached
4 Assertions should be caught with a try catch block
5 assert true will throw an AssertionError
6 Causing side affects with assertions is correct for debugging
12 Which two of the following statements are false?
1 You can use the command line
java -ea to enable assertions
2 You can use assert as an identifier and have your code compile without error
3 Assertions are typically on during debugging and off in the production version
4 You can use the command line java -source 1.4 to enable assertions
5 Assertions are a replacement for exceptions
6 The
word assert is a keyword as of version 1.4
1- Objective 2.1
6 5 true
It is valid to have any expression which evaluates to a boolean as the argument for an if statement. Both the a = 4 and b = true are assignments, not comparisons. Thus b = true evaluates to true, and a is incremented to 5. The System.out.print(a) always executes regardless of the if statement above it.
2- Objective 2.1
2,5
2- can not switch on any type except those which can be promoted to integer
5- Integer is an Object, not a primitive which can be switched on
3- Objective 2.2
5- 1345678910
4- Objective 2.2
1 Compilation fails
The continue should read "continue outside;" and the break "break inside;". If it were corrected in this way, the output would be 0123012301230
5 Objective 2.3
3,4 are false
1 - True, all exception classes also derive from Object
2 - You catch multiple types of exceptions which all derive from your caught
exception
3 - False, a System.exit(0); in the catch will skip the finally from executing
4 - False, you do not need to explicitly handle RunTimeExceptions
5 - True, you can throw an exception out of main
6 - This is true, try writing the code
6 Objective 2.3
1 throw new MyExcept(); is correct
7 Objective 2.4
6 - abd10
The division by zero on an integer does throw an AirthmeticException which is caught by the first catch clause.
8 Objective 2.3
1 - Compile time error
A compile time error is generated by the line "System.out.print("2")"
9 Objective 2.5
2,4,6
1 False it is not appropriate to modify a value as a side effect of an assert
2 True- this is an appropriate check and will print out the number of students
3 False System.out.print returns a type void, which is not allowed
4 True this will throw an AssertionError if score is not greater than 0
5 False assert true will never do anything
6 True assert false is appropriate in code you think will never execute
10 Objective 2.5
3 bigger Exception in thread "main" java.lang.AssertionError: bigger
This first assert comes out to be false. It prints out the
string, then returns this which is appended to the Exception error
11 Objective 2.6
1,3 are true
1 True- Often switch statements should not use default, and assert false is a good way to discover if they are hitting the default handler by mistake
2 False- assertions should not be to check your publically exposed interfaces, this should be done with if statements
3 True- this is a good way to use the assert mechanism
4 False- assertions should not be handled- they should terminate the program
5 False- assert false will throw an AssertionError
6 False- assertions should not cause side effects
12 Objective 2.6
4,5 are false
1 True you use java -ea to enable assertions
2 True- code compiled not as source 1.4 can use assert but it will generate warnings
3 True- assertions are typically used for the
testing environment only
4 False, you use the command line javac - source 1.4 to compile in assertions
5 False, assertions are not a replacement for exceptions
6 True- assert is a keyword as of version 1.4
Section 2: Flow control, Assertions, and Exception Handling
1 Write code using if and switch statements and identify legal argument types for these statements.
2 Write code using all forms of loops including labeled and unlabeled, use of break and continue, and state the values taken by loop counter variables during and after loop execution.
3 Write code that makes proper use of exceptions and exception handling clauses (try, catch, finally) and declares methods and overriding methods that throw exceptions.
4 Recognize the effect of an exception arising at a specified point in a code fragment. Note: The exception may be a runtime exception, a checked exception, or an error (the code may include try, catch, or finally clauses in any legitimate combination).
5 Write code that makes proper use of assertions, and distinguish appropriate from inappropriate uses of assertions.
6 Identify correct statements about the assertion mechanism.
[ September 16, 2004: Message edited by: Tom Tolman ]
