Task 3: Thinking Objects

What does class abstraction mean in Java?

• To allow direct access to class variables

• To define a class without any methods

• To create multiple instances of a class

• To hide the implementation details from the user

Which of the following is a characteristic of encapsulation?

• All methods must be static

• Class variables are declared as public

• Class implementation is exposed to the user

• Private variables can be accessed using public methods

What is the purpose of the get method in a class?

• To create a new variable

• To return the value of a variable

• To set the value of a variable

• To delete a variable

What is the relationship type called when one class contains a reference to another class?

• Composition

• Aggregation

• Association

• Inheritance

Which of the following statements about composition is true?

• Composition is the same as inheritance

• The aggregated object is dependent on the owner object

• The owner object can exist without the aggregated object

• The aggregated object can exist independently

Which of the following is NOT a wrapper class in Java?

• Character

• Integer

• Double

• String

What is the purpose of the valueOf method in wrapper classes?

• To convert a string to a primitive type

• To create a new object from a string

• To parse a string into a number

• To compare two wrapper objects

What does the String class in Java represent?

• A mutable sequence of characters

• An immutable sequence of characters

• A collection of strings

• A character array

Which method is used to split a string into an array of substrings?

• substring()

• concat()

• replace()

• split()

What is the output of the statement 'String s = "Java"; s = "HTML";'?

• The string s remains Java

• The string s is changed to HTML

• s is null

• An error occurs