Itec30

Question 1

IT ENABLES YOU TO DEFINE SUPERCLASS AND SUBCLASSES

Answer 1

INHERITANCE

Question 2

THIS METHOD RETURNS A STRING REPRESENTATION OF THE OBJECT

Answer 2

TO STRING()

Question 3

IT IS A TYPE THAT DEFINED BY A SUBCLASS

Answer 3

SUBTYPE

Question 4

IT IS A TYPE THAT DEFINED BY A SUPERCLASS

Answer 4

SUPERTYPE

Question 5

IT MEANS THAT A VARIABLE OF A SUPERTYPE CAN REFER TO A SUBTYPE OBJECT.

Answer 5

POLYMORPHISM

Question 6

It can also be used to convert an object of one class to another within an inheritance hierarchy.

Answer 6

CASTING

Question 7

It can be used to test whether an object is an instance of a class.

Answer 7

INSTANCE OF OPERATOR

Question 8

It is another method that defined in the object class that often used.

Answer 8

EQUAL METHOD

Question 9

It is a modifier can be applied on a data and methods in a class.

Answer 9

PROTECTED MODIFIER

Question 10

It is a modifier that indicates that a class is cannot be a parent class

Answer 10

FINAL MODIFIER

Question 11

It is an object that represents an error or a condition that prevents execution from proceeding normally.

Answer 11

EXCEPTION

Question 12

It is thrown if you access an object through a reference variable before an object is assigned to it.

Answer 12

NullPointerException

Question 13

It is thrown if you access an element in array outside the bounds of array.

Answer 13

IndexOutOfBoundsException

Question 14

Every method must state the types of checked exceptions it might throw. This is known as .

Answer 14

DECLARING EXCEPTIONS

Question 15

When the program detects an error, the program can create an instance of an appropriate exception type and throw it. This is known as .

Answer 15

THROWING EXCEPTION

Question 16

It is declared using the new Java keyword assert in JDK 1.4

Answer 16

ASSERTION

Question 17

It is intended to provide an abstraction that deals with most of machine-dependent complexities of files a path names in a machine-independent fashion.

Answer 17

FILE CLASS

Question 18

The directory separator for Windows is a .

Answer 18

BACKSLASH

Question 19

It is the Java directory separator.

Answer 19

FORWARDSLASH

Question 20

It is in relation to the current working directory.

Answer 20

RELATIVE FILE NAME

Question 21

T OR F

Every class in Java is descended from the java.lang.Object class.

Answer 21

TRUE

Question 22

T OR F

The Object class is the parent class of all the classes in java by default.

Answer 22

TRUE

Question 23

T OR F

Polymorphism occurs when a program invokes a method through a superclass variable.

Answer 23

TRUE

Question 24

T OR F

Explicit casting must be used when casting an object from a superclass to a subclass.

Answer 24

TRUE

Question 25

T OR F The Math class is a final class

Answer 25

TRUE

Question 26

T OR F A subclass inherits methods from a superclass. Sometimes it is necessary for the subclass to modify the implementation of a method defined in the superclass. This is referred to as method overriding.

Answer 26

TRUE

Question 27

T OR F To override a method, the method must be defined in the subclass using the same signature and the same return type as in its superclass.

Answer 27

TRUE

Question 28

T OR F Like an instance method, a static method can be inherited. However, a static method cannot be overridden.

Answer 28

TRUE

Question 29

T OR F If a static method defined in the superclass is redefined in a subclass, the method defined in the superclass

Answer 29

TRUE

Question 30

T OR F Java do not require that the statement that uses the keyword super appear first in the constructor.

Answer 30

FALSE

Question 31

T OR F Runtime errors occur while a program is running if the JVM detects an operation that is impossible to carry out.

Answer 31

TRUE

Question 32

T OR F If the exception is handled, the program will terminate abnormally.

Answer 32

FALSE

Question 33

T OR F The exception is an object created from an exception class.

Answer 33

TRUE

Question 34

T OR F The constructor ArithmethicException(int) is invoked to construct an exception object, where int is a message that describes the exception.

Answer 34

FALSE

Question 35

T OR F The try block contains the code that is executed in normal circumstances.

Answer 35

TRUE

Question 36

T OR F The exception is caught by the fetch block to handle the exception.

Answer 36

FALSE

Question 37

T OR F The root class for exceptions is java.lang.Throwable.

Answer 37

TRUE

Question 38

T OR F You can create your own exception classes by extending Exception or a subclass of Exception.

Answer 38

FALSE

Question 39

T OR F Exception describes errors caused by your program and external circumstances.

Answer 39

TRUE

Question 40

T OR F All other exceptions are known as error exceptions.

Answer 40

FALSE

Question 41

A Subclass inherits from a superclass. You can also: 1. 2. 3.

Answer 41

1. Add new properties 2. Add new methods 3. Override the methods of the superclass

Question 42

Modifier on members in a class 1. 2. 3. 4.

Answer 42

1. Public 2. Default 3. Protected 4. Private

Question 43

Final modifier characteristics 1. 2. 3.

Answer 43

1. The final class cannot be extended 2. The final variable is a constant 3. The final method cannot be overridden by its subclass

Question 44

Runtime Exception, Error and their subclasses are known as_____________

Answer 44

Unchecked Exceptions.

Question 45

___________ are checked at compile time.

Answer 45

Checked Exceptions

Question 46

An assertion contains a __________ that should be true during program execution.

Answer 46

Boolean Exceptions

Question 47

Since _______ is a new Java keyword introduced in JDK 1.4, you have to compile the program using a JDK 1.4 compiler.

Answer 47

ASSERT

Question 48

The filename is a _________.

Answer 48

STRING

Question 49

An ______________ contains a file name with its path and drive letter.

Answer 49

ABSOLUTE FILE NAME

Question 50

In order to perform I/O, you need to create objects using appropriate _______________-.

Answer 50

Java I/O Classes.

Question 51

On the ___________, the absolute file name maybe /home/liang/book/Welcome.java.

Answer 51

UNIX Platform

Question 52

The File class is a ____________ for the file name and its directory path.

Answer 52

Wrapper Class

Question 53

_________- are thrown by JVM and represented in the Error class.

Answer 53

System Errors