Week 3 Part 2

Question 1

When a parameter is passed to a method, it is known as

Answer 1

an argument

Question 2

Classes that are compiled in the same directory are considered to be in the same _______

Answer 2

package

Question 3

Most classes in Java programs need to be imported __________, by typing ______ followed by the class name

Answer 3

explicitly, import

think import java.utl

Question 4

Classes that are in the same package, are they imported explicitly or implicitly?

Answer 4

Implicitly

Question 5

For classes, what other situation is there where an import declaration is not required?

Answer 5

Not required if the class is referred to with a full qualified method name, including its package and class names.

Question 6

Describe UML design. How many compartments? Where is the class name? Where are the class attributes? What are attributes? Where are the class operations? What are class operations?

Answer 6

3 compartments, class name in the top one. Class attributes in the second, which correspond to instance variables. Class operations in the third, which correspond to methods and constructors.

Question 7

How are instance variables represented in UML?

Answer 7

-name:type

Question 8

How are operations represented in UML?

A setter for example

Answer 8

+setName(name:type)

Question 9

Apparently everything you learned in semester 1 is wrong. In UML do operations that don’t have a return type have a return value? (void)

Answer 9

Apparently not. If they do have return value it looks like this +getName():type

Question 10

What happens if a class does not define constructors? What happens to the classes instance variables if this is the case?

Answer 10

The compiler provides a default constructor with no params. The instance vars are initialized to their default values

Question 11

T/F - A default constructor will still be created if there is a declared constructor

Answer 11

False

Question 12

T/F - Java requires a constructor call for every object that is created

Answer 12

True

Question 13

T/F - Constructors specify return types

Answer 13

False

Question 14

How does UML distinguish a constructor from class operations?

Answer 14

Places the word constructor between Guillemets “&laquo_space;»” pronounced GILL MITTS

«constructor»Account(name:type)

Question 15

How does a compiler select the appropriate method to call when there’s overloading? What is this called? Explain the mechanisms behind this function

Answer 15

Inspects the:

number of arguments
types of arguments
order of arguments

It’s called the Method signature

Question 16

test (float, int)
test (int, float)

Will it work?

Answer 16

Yes, they’re in a different order

Question 17

If 2 method have a different return type but the same arguments, will method overloading occur?

Answer 17

No, that would invalid method overloading

Question 18

What are 2 advantages on method overloading?

Answer 18

Flexibility, readability

Question 19

Used to implement an object in different ways

Answer 19

Constructor overloading

Question 20

Like method overloading, how does the compiler select the correct constructor?

Answer 20

Inspects the methods signature

Question 21

4 advantages of constructor overloading

Answer 21

1. Can create new objects when you have differing amounts of data to pass
2. Variety of way to create an object
3. When adding a constructor, the compiler will not add a default no-arg constructor
4. A constructor eliminates calling the normal or ordinary method implicitly

Question 22

What is constructor chaining? Can you have constructor chaining with no overloaded constructors?

Answer 22

When a call to a constructor is made from inside another constructor in the same class. This makes constructor chaining w/ no overloaded constructors impossible.

Question 23

3 benefits of constructor chaining

ACE

Answer 23

1. Avoids code duplication
2. Consistent Usage
3. Ease of maintenance

Question 24

What term do we use for constructor chaining? What is notable about it?

Answer 24

this(). Has to be the first line in the constructor.

Question 25

Can every constructor utilize this()? What does it represent?

Answer 25

No, at least one must not have it. this() represents an object being constructed.

Question 26

Is there is a restricted order to chaining?

Answer 26

No, chaining can be realized in any given order.