Functions and Modules

Question 1

What is a method in Java?

Answer 1

a method is a section of the program that contains a set of instructions. When the method is called, the set of instructions within the method is executed.

Question 2

What are parameters in a Java method?

Answer 2

data that are inputted or passed into the method

Question 3

Identify the name, parameters in the Java method below:

public int calculateAge ( int m, int n) {
statements…}

Answer 3

calculateAge is the name of the method
m,n are the parameters

Question 4

What is the first method executed in Java?

Answer 4

the main method

Question 5

Why is the main method in Java declared as static?

Answer 5

because it allows the main method to be called as the first method without having to create an instance of the method.

Question 6

How is the return value declared in a method?

Answer 6

By the data type alone before the method name

Question 7

Can Java methods return more than one value?

Answer 7

No Java methods can only return one or no values.

Question 8

The number of strings passed into the main method’s local variable named args can be obtained via _____.

Answer 8

args.length

The number of elements stored in any Java array is kept in an internal property named length. Therefore args.length will return the number of elements in the String array args.

Question 9

_____ are passed to the main method as an array of String objects.

Answer 9

The command line options.

The space separated command line options (which occur AFTER the name of the file containing the Java program) are passed to the main method.

Question 10

If you want to protect members of a class, but still allow other classes in the package, or subclasses to use them, the __________ keyword can be used.

Answer 10

protected

Question 11

A ____________ is a class that inherits variables and methods from another class. Private members can’t be shared down to children, but protected members can.

Answer 11

subclass

Question 12

A __________ in Java is like a project: it is a group of similar class types all contained within the same set of code.

Answer 12

package

Question 13

The _________ keyword provides the highest level of protection for members of classes.

Answer 13

private

Question 14

It is recommended to create most methods and variables as _____.

Answer 14

private

Question 15

Which type of variable or method is protected but can be used with classes in the package (and also subclasses)?

Answer 15

Protected

Question 16

The Java _______ keyword protects code, variables, classes, and methods. It ensures you can’t create subclasses from the main class. It ensures variables stay local to their methods.

Answer 16

final

Question 17

When used to create a class, the final keyword will prevent the creation of _____

Answer 17

A subclass from the class

Question 18

Trying to create a subclass from a final class, or re-initialize a final variable, will result in what?

Answer 18

Compiler errors: program will not run

Question 19

Final can be used to protect the following:

Answer 19

Variables, methods, and classes

Question 20

What is a static method?

Answer 20

A static method in Java (also called class method) is a method that belongs to the class and not the instance. Therefore, you can invoke the method through the class instead of creating an instance first and calling the method on that instance.

Question 21

What is the difference between an instance method and a static method?

Answer 21

Static methods should be accessed through class and not instance

Question 22

Given a class Example with static method called action with no parameters, which of the following is never a correct call for the static method ?

Answer 22

cannot use the keyword this as there is no instance

Question 23

To make a method a static method we need to:

Answer 23

Add the keyword ‘static’ to the method signature

Question 24

What does a static method belong to?

Answer 24

In Java a static method belongs to the class

Question 25

What does a non-static method belong to?

Answer 25

In Java a non-static method belongs to the object of a class.

Question 26

Characteristics of static methods:

Answer 26

A static method can call only other static methods; it cannot call a non-static method

A static method can be called directly from the class, without having to create an instance of the class

A static method can only access static variables; it cannot access instance variables

Since the static method refers to the class, the syntax to call or refer to a static method is: class name.method name

To access a non-static method from a static method, create an instance of the class

Question 27

Characteristics of Non-Static Methods:

Answer 27

can access any static method or variable without creating an instance of the class

Question 28

What is modular programming?

Answer 28

instead of writing a program as one large block of code, we divide it into small and independent modules,

Question 29

An object is implemented as a Java class and has a name, some characteristics (called _________) and some actions (__________) that can be performed on it or by it.

Answer 29

attributes, methods

Question 30

Each Java ________ represents a noun (for example, Student, Car, Building, Address, Reservation, etc.). One way to think of the Java class is as a __________.

Answer 30

class, template

Question 31

Class characteristics and data we want to store related to that class are called _________________________.

Answer 31

class attributes

Question 32

The _____________, which is where a Java program always starts executing, is a static method because when it starts, there are no _________ of any classes yet.

Answer 32

main method, instances

Question 33

java.util

Answer 33

classes for lists, maps, queues, sets, arrays, date, scanner for reading data, etc.

Question 34

java.lang

Answer 34

fundamental classes for stdin and stdout (System), data types (Boolean, Character, Integer, etc.), math methods (Math), and more

Question 35

java.awt

Answer 35

classes for creating user interfaces, graphics, and images

Question 36

java.swing

Answer 36

classes and support for GUI components

Question 37

When passing an array to the function where is the reference to the array stored?

Answer 37

The parameter variable.

Question 38

Arrays allow the storing of multiple values of the ______ data type.

Answer 38

same

Question 39

In programming, a __________ method is like this: it calls itself over and over until something triggers its exit.

Answer 39

recursive

Question 40

When a Java function calls itself, it’s known as _________. When we have a repeating loop, we’re using ___________.

Answer 40

recursion, iteration

Question 41

What are measures of performance?

Answer 41

Execution time and memory usage

Question 42

What can help prevent infinite loops?

Answer 42

An exit point