2023 Assesment Exam

Question 1

Define syntax

Answer 1

refers to the set of rules that define the structure of a program

Question 2

Define Java API

Answer 2

Application Programming Interface, is a collection of pre-written software components that developers can use in their Java programs.

Question 3

Define a Variable

Answer 3

a named storage location in memory that holds a value during program execution.

Question 4

Define source code

Answer 4

the set of instructions written by a programmer using the Java programming language.

Question 5

Define an Algorithm

Answer 5

set of well-defined instructions that are executed in a specific order to solve a particular problem

Question 6

State examples of eselctive control structures

Answer 6

sequence , The If statement , the Switch(case) statement , iteration loops(For Loop, Do-while loop, while loop)

Question 7

Assume that there is a java class called Test and it has not been compiled but we want to run it.
i. Identify the appropriate command to use to compile this class on command line interface.

Answer 7

javac Test.java

Question 8

Assume that there is a java class called Test and it has not been compiled but we want to run it.

Answer 8

java Test

Question 9

Use one java instruction to write a statement that displays the following output on the screen.
Hello
World

Answer 9

System.out.println(“Hello”+”\n”+”World”);

Question 10

Identify (3) rules which a programmer must consider when using a loop that should terminate at some point.

Answer 10

1. INITIALIZE the loop control variable outside the loop
2. Use the loop control variable as a variable in the loop
3. Alter the loop control variable

Question 11

Identify a loop which should be used in a situation where it should execute at least once.

Answer 11

Do while statement

Question 12

Justify why statements in the body of a loop must be indented.

Answer 12

• Improve legibility
• Improve readability
• Neatness

Question 13

Define Sub routines

Answer 13

Methods are essentially self-contained blocks of code that perform specific tasks within a class.

Question 14

Define a constructor

Answer 14

a constructor is a special type of method that is called automatically whenever you create an object of a class using the “new” keyword.

Question 15

Give an example demonstrating how subroutines/methods are defined in Java

Answer 15

public static void add(int a, int b ){
int sum;
sum = a + b;
}

Question 16

Differentiate between a void and non-void subroutine?

Answer 16

A void method does not return a value while a non void returns a value.

Question 17

Why is it important to use parameterized constructors.

Answer 17

because they allow you to create objects with specific initial values, making your objects more flexible and customizable.

Question 17

What is the purpose of assignment operators in Java? Give an example.

Answer 17

assign values to variables. e,g
int age = 25

Question 17

How can you use the += operator in Java to increment a variable’s value by a specified amount? Give an example.

Answer 17

The += operator in Java is a shorthand way to increment a variable by a specified amount. It combines addition and assignment.
e,g
int count = 5;
count += 3; // Equivalent to count = count + 3; // Now count will be 8

Question 18

What is implicit cast in Java? Provide an example of implicit

Answer 18

Implicit casting (widening conversion): Automatic conversion of smaller data types to larger ones (e.g., int to double). No data loss, happens automatically.

int x = 10; double d = x; // No cast needed

Question 19

What is explicit cast in Java? Provide an example of explicit.

Answer 19

Explicit casting (narrowing conversion): Manual conversion of larger data types to smaller ones (e.g., double to int). Possible data loss, requires the cast operator (type).

double d = 3.14; int x = (int) d; // Possible data loss (decimal part truncated)

Question 20

Define a literal in Java and provide examples of 5 different types of literals.

Answer 20

A literal in Java is a fixed value directly written in your code. It represents a constant data that cannot be changed during program execution.
e,g ; integer , character , String , Double , Float, Boolean.

Question 21

explain 4 primitive data types

Answer 21

Primitive Data Types: These are basic building blocks that hold specific data types and have predefined sizes in memory.:

byte: Stores small whole numbers (8 bits).
short: Stores whole numbers (16 bits).
int: Stores whole numbers (32 bits, commonly used).
long: Stores large whole numbers (64 bits).

Question 22

explain reference data types

Answer 22

Non-primitive Data Types: These are reference types that refer to objects in memory. They are more complex and user-defined. Examples include:

String: Represents text data.

Question 23

you didnt do arrays and coding questions boy!!