ITCS 1213 Final Exam
Which type of classes cannot be instantiated
abstract
A java interface contains only
abstract method headings and public final fields
When a class implements an interface it must provide what
all the methods that are listed in interface with exact signatures and return types specified
What are ragged arrays
arrays with different columns in each row
How man interfaces can another class implement
as many as needed
Which is subclass in the heading: Public class classA extends classB implements classC
classA
One or more statements that are always executed after the try block has executed and after any catch blocks if exception was thrown
finally block
This method is used to retrieve the error message from an Exception
getMessage())
What is the command to run a java program from command prompt
java fileName
What is the command to compile code from command prompt
javac fileName.java
What does Java assign each object in an array of objects
null
All classes directly or indirectly inherit from
object class
How many classes can a given class extend
one
What is two or more methods in the same class definition file having the same name but different signatures
overloading
What data type is a char
primitive
These superclass members are accessible only to the subclasses and class in the same package
protected
The following is an explicit call to the superclass's default constructor
super();
A checked Exception is checked by
the Java compiler
What is required for two methods to have the same signatures
the name of the methods and the data type of the parameters need to be the same
This informs the compiler of the Exceptions that could get thrown for a method
throws clause
What is meant by args?
An array of arguments
What does super do in this code? public class classB extends classA { Public classB() { Super(10) } }
It will call the constructor of ClassA that receives an integer as an argument
What will happen If a subclass constructor does not explicitly call a superclass constructor
Java will automatically call the superclass's default constructor just before the code in the subclass's constructor executes
All static class members must be declared with what access
Public
What is the access specifier for access to all methods
Public
What are two categories of errors in Java
Runtime (unchecked) Exceptions & Checked Exceptions
What line of code creates a Scanner object to read data from a file
Scanner input = new Scanner(new File("c:\\file.txt"));
T/F: A class may extend at most one superclass
True
T/F: A superclass constructor always executes before the subclass constructor
True
T/F: Every class has a toString method and an equal's method inherited from Object class
True
T/F: It is not possible for a superclass to call a subclass method
True
What is each element in a numerical array initialized to
0
In a subcass constructor, a call to the superclass constructor must
Appear as the very first statement
What is difference between a checked exception an unchecked
Checked exception must be either declared that it may occur or be caught in your code
What is meant by the error going up through the call stack
Error Propagation
This is the keyword that indicates a class inherits from another class
Extends
T/F: A class may implement at most one interface
False
T/F: A programmer can code only one thrown exception in a try block
False
T/F: All methods in an abstract class must also be declared abstract
False
T/F: If a method in a subclass has the same signature as a method in the superclass, the subclass method overloads the superclass method
False
T/F: Overloading methods and overriding methods are synonymous
False
T/F: If two methods in the same class have the same name but different signatures, the second overrides the first
False (overloading)
List the exceptions in the order they should be caught
FileNotFoundException, IOException, Exception
What kind of fields cannot be changed
Final
What block in exception-handling mechanism is optional?
Finally block
What line of code opens a file for output
PrintWriter outputFile = new PrintWriter("c:\\file.txt"));
A subclass does not have access to these superclass members
Private
Which access specifier give access of members to any subclass and classes in the same package only
Protected
In an inheritance relationship, this is the general class
Superclass
Any object that can be thrown as an Exception must inherit from this class
Throwable
What are two reasons for interfaces in Java
To implement a list of methods and organization