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

toString()

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

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.

Answer 15

throwing exception / throwing an 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

directory separator for windows

Answer 18

backslash

Question 19

java directory separator

Answer 19

forward slash

Question 20

it is in relation to the current working directory

Answer 20

relative file name

Question 21

Modifier on members in a class

Answer 21

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

Question 22

Final modifier characteristics

Answer 22

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 23

Runtime Exception, Error and their subclasses are known as

Answer 23

Unchecked exceptions

Question 24

_______checked at compile
time.

Answer 24

checked exceptions

Question 25

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

Answer 25

boolean expression

Question 26

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

Answer 26

assert

Question 27

filename is a ____

Answer 27

string

Question 28

______ contains a file name with its path and drive letter.

Answer 28

absolute filename

Question 29

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

Answer 29

java i/o classes

Question 30

absolute filename maybe home/liang/book/welcome java

Answer 30

UNIX platform

Question 31

the file class is a ____ for the file name and its directory path

Answer 31

wrapper class

Question 32

_____ are thrown by JVM and represented in the error class

Answer 32

system errors

Question 33

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

Answer 33

true

Question 34

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

Answer 34

true

Question 35

Polymorphism occurs when a program invokes a method through a superclass variable. T or F

Answer 35

true

Question 36

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

Answer 36

true

Question 37

The Math class is a final class. T or F

Answer 37

true

Question 38

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 T or F

Answer 38

true

Question 39

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. T or F

Answer 39

true

Question 40

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

Answer 40

true

Question 41

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

Answer 41

true

Question 42

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

Answer 42

false

Question 43

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

Answer 43

true

Question 44

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

Answer 44

false

Question 45

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

Answer 45

ttrue

Question 46

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

Answer 46

false

Question 47

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

Answer 47

true

Question 48

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

Answer 48

false

Question 49

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

Answer 49

true

Question 50

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

Answer 50

false

Question 51

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

Answer 51

true

Question 52

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

Answer 52

false