PPJ

Question 1

Physical components like processors, memory, storage, and input/output devices.

Answer 1

Hardware

Question 2

Software that manages hardware and provides services to applications.

Answer 2

Operating System

Question 3

Tools used to create software instructions.

Answer 3

Programming Language

Question 4

The smallest unit of data (0 or 1).

Answer 4

Bits

Question 5

A sequence of 8 bits.

Answer 5

Bytes

Question 6

A base-16 numbering system used for representing binary data.

Answer 6

Hexadecimal

Question 7

The central processing unit that executes instructions.

Answer 7

Processor

Question 8

Basic operations performed by the processor.

Answer 8

Instructions

Question 9

A sequence of instructions that performs a task.

Answer 9

Program

Question 10

Translates human-readable code into machine code.

Answer 10

Compiler

Question 11

Close to machine code (e.g., assembly language).

Answer 11

Low-level

Question 12

More human-readable (e.g., Python, Java, C++).

Answer 12

High-level

Question 13

values in the range [−128,127];

Answer 13

byte (1)

Question 14

values in the range [−32 768,32 767];

Answer 14

short (2)

Question 15

values in range[0,65 535] interpreted as Unicode code
points of characters (always non-negative);

Answer 15

char(2)

Question 16

values in the range [−2 147 483 648,2 147 483 647];

Answer 16

int (4)

Question 17

values in an astronomical range [−9 223 372 036 854 775 808, 9 223 372 036 854 775 807].

Answer 17

long (8)

Question 18

values in the range [≈1.4·10−45,≈ 3.4·10+38] positive or negative, with roughly 7 significant decimal digits – rarely used;

Answer 18

float (4)

Question 19

values in the range [≈4.9·10−324 ≈ 1.8·10+308] positive or negative, with roughly 16 significant decimal digits.

Answer 19

double (8)

Question 20

has only two possible values: true and false.

Answer 20

boolean

Question 21

Built-in data types for basic values like numbers or characters

Answer 21

Primitive types

Question 22

User-defined or pre-defined complex data structures.

Answer 22

Object types

Question 23

are named storage locations in memory that hold specific data types. Only primitive types can be directly assigned names. Object types are accessed through references.
Literals are the actual data values assigned to variables.

Answer 23

Variables

Question 24

Primitive types are stored on the ___, while objects reside on the ___

Answer 24

stack, heap

Question 25

automatically manages memory allocation and deallocation for objects

Answer 25

garbage collector

Question 26

0 1 1 0 1 1 0 0
0 1 0 1 0 1 0 1
6
—————
& 0 1 0 0 0 1 0 0

Answer 26

AND

Question 27

0 1 1 0 1 1 0 0
0 1 0 1 0 1 0 1
—————
| 0 1 1 1 1 1 0 1

0 1 1 1 1 1 0 1

Answer 27

OR

Question 28

0 1 1 0 1 1 0 0
0 1 0 1 0 1 0 1
—————
^ 0 0 1 1 1 0 0 1

Answer 28

XOR

Question 29

~ 0 1 1 0 1 1 0 0 -> 1 0 0 1 0 0 1 1

Answer 29

Negation

Question 30

• A region of memory used for storing local variables and function call information.
• Follows LIFO (Last-In-First-Out) principle: values are added and removed from the top.
• Automatically managed by the JVM.
• Efficient for accessing and storing data.
• Variables declared within blocks are typically stored on the stack.

Answer 30

Stack

Question 31

• A region of memory used for dynamically allocated objects.
• Requires manual memory management (allocation and deallocation).
• Slower to access than the stack due to pointer indirection.
• Objects created using new are stored on the heap.
• The garbage collector automatically reclaims unused heap memory.

Answer 31

Heap

Question 32

• \a – (BEL) alert;
• \b – (BS) backspace;
• \f – (FF) form-feed (new page);
• \n – (LF) new line (linefeed);
• \r – (CR) carriage return;
• \t – (HT) horizontal tab;
• \v – (VT) vertical tab;
• \’ – apostrophe;
• " – quotation mark;
• \– backslash;

Question 33

double x = 7.7;
int a = (int)x;

Question 34

Symbols that represent actions to be performed on values (operands).

Answer 34

Operators

Question 35

operate on two operands (e.g., +, -, *, /).

Answer 35

Binary operators

Question 36

operate on one operand (e.g., ++, –).

Answer 36

Unary operators

Question 37

is the only operator with three operands.

Answer 37

Ternary operator (?:)

Question 38

Work with int, long, float, and double.

Answer 38

Arithmetic types

Question 39

Operands may be converted to match the same type

Answer 39

Implicit conversion

Question 40

Truncates the fractional part towards zero.

Answer 40

Integer division:

Question 41

Remainder follows the sign of the first operand.

Answer 41

Negative operands

Question 42

System.out.println(“ 7 / 2 = “ + ( 7 / 2 ));

Question 43

Determines the order of operations when multiple
operators are present.

Answer 43

Operator Precedence:

Question 44

• Defines the grouping of operands with the same
  precedence.
• Most operators are left-to-right associative.

Answer 44

Associativity

Question 45

are single orders for the computer to perform.
* They often correspond to multiple low-level machine instructions.

Answer 45

Instructions

Question 46

are instructions that have a value (expressions) or don’t (e.g., variable declarations).

Answer 46

Statements

Question 47

Used to control program flow based on conditions.

Answer 47

Conditional Statements

Question 48

if statement: executes a block of code if a condition is true.
else if statements: optional checks for additional conditions if the first fails.
else statement: optional block to execute if none of the previous conditions are true.

Question 49

are expressions that evaluate to true or false.

Answer 49

Conditions

Question 50

Similar to if statements but with multiple conditions.
Evaluates a selector expression against case values.
Executes code associated with the matching case.
break statement: exits the switch after a case is matched (optional).
default clause: executes if no case matches (optional).

Answer 50

Switch Statements

Question 51

Used to repeat a block of code multiple times.

Answer 51

Loops

Question 52

Executes the body as long as a condition is true.
Checks the condition before each iteration.

Answer 52

while loop

Question 53

Similar to while but executes the body at least once.
Checks the condition after each iteration.

Answer 53

do-while loop

Question 54

Concise loop construct with initialization, condition, and increment/decrement.
Executes the body as long as the condition is true, updating the expression after each iteration.

Answer 54

for loop

Question 55

are the simplest data structure.
* They store a fixed-size collection of elements of the same type.
* Elements are ordered and accessed using their index (starting from 0).

Answer 55

Arrays

Question 56

are created using the new keyword followed by the type and size in square brackets ([]).
* The size cannot be changed after creation.
* Example: int[] arr = new int[10]; creates an array of 10 integers.

Answer 56

Arrays

Question 57

• Elements are accessed using their index within square brackets (arr[i]).
• Example: arr[3] = 25; assigns the value 25 to the fourth element (index 3).

Question 58

• The for loop is commonly used to iterate through each element.
  o for (int i = 0; i < arr.length; i++) { … }
• Alternatively, the for-each loop can be used for concise iteration.
  o for (int element : arr) { … }

Question 59

don’t exist directly in Java.
* Instead, you create arrays of references to objects.
* Example: String[] names = new String[5];

Answer 59

• Arrays of objects

Question 60

• Java doesn’t have true multi-dimensional arrays.
• Arrays can hold references to other arrays, simulating multiple dimensions.
• Example: int[][] matrix = new int[3][4]; creates a 3x4 matrix of integers.

Question 61

• Definition: Functions declared with the static keyword belong to the class itself, not to instances of the class.
• Access: Invoked using the class name followed by a dot (.) and the function name (ClassName.functionName()).

Answer 61

Static Functions

Question 62

Static Functions

• Components:
  o static keyword
  o Return type …
  o Function name …
  o Parameter list …
  o Function body …

Answer 62

(or void if no return value)
(starts with a lowercase letter)
(optional, enclosed in parentheses)
(enclosed in curly braces)

Question 63

o Arguments passed are copies of values, pushed onto the program stack.
o Function operates on these copies, originals remain unchanged.
o Arrays are passed by reference (address of the array), but modifications affect the original array.

Answer 63

Static Functions

Question 64

o Can call themselves within their definition.
o Important to have a base case to prevent infinite recursion.

Answer 64

• Recursive Functions:

Question 65

o Defining multiple functions with the same name but different parameter lists.
o Compiler chooses the appropriate function based on argument types.
o Useful for functions with similar functionality but different input types.

Answer 65

• Function Overloading:

Question 66

Represent real-world entities with data (fields) and actions (methods).

Answer 66

• Objects

Question 67

Define blueprints for creating objects with specific characteristics.

Answer 67

• Classes

Question 68

Fields and methods that belong to a class.

Answer 68

• Members

Question 69

Accessed through object references.

Answer 69

o Non-static members

Question 70

Belong to the class itself, accessed without object references

Answer 70

o Static members

Question 71

• The new operator is used to create objects from a class definition.
• The object gets its own copy of non-static fields.
• Static fields are shared among all objects of the class.

Answer 71

Creating Objects

Question 72

• Non-static methods are invoked on object references using dot notation (.).
• Static methods are accessed using the class name followed by the dot notation.

Answer 72

Member Access:

Question 73

• Access control keywords (public, private, protected, default) determine how members can be accessed from other classes.

Answer 73

Member Visibility

Question 74

• Special methods with the same name as the class.
• Used to initialize object fields during creation.
• Can be overloaded (have different parameter lists).

Answer 74

Constructors

Question 75

• Methods used to access and modify private fields.

Answer 75

Getters and Setters:

Question 76

• Used for data or functions common to all objects of the class.
• Accessible even before creating any objects.

Answer 76

Static Members

Question 77

• Immutable: Once created, their content cannot be changed.
• Better for security and thread safety: Modifications require creating new objects, which makes them less prone to errors and safer in multi-threaded environments.
• Used for constant data: Ideal for storing data that won’t be modified, like configuration values or text displayed on the screen.
• Slower for frequent modifications: String concatenation with the + operator creates new String objects each time.

Answer 77

Strings

Question 78

• Mutable: Their content can be modified after creation.
• More efficient for frequent changes: Operations like append, insert, and delete directly modify the internal character array, avoiding unnecessary object creation.
• Can be less secure and thread-unsafe: Modifications happening concurrently can lead to unexpected results. Use with caution in multi-threaded environments.
• Used for building strings dynamically: Great for scenarios where you need to construct a string by combining different parts.

Answer 78

StringBuilders

Question 79

• Ordered sequence of elements.
• Each element (node) holds data and a reference to the next node.
• Efficient for adding/removing elements at the beginning or end.
• Less efficient for random access or modifying elements in the middle.
• Good for implementing stacks and queues.

Answer 79

Singly Linked Lists

Question 80

• Elements are added (pushed) and removed (popped) from the top.
• Think of a stack of plates - you remove the top plate first.
• Implemented using singly linked lists (adding/removing from the front) or arrays.
• Used for function calls, undo/redo functionality, and expression evaluation.

Answer 80

Stacks (LIFO - Last In, First Out)

Question 81

• Elements are added (enqueued) at the back and removed (dequeued) from the front.
• Think of a line at a store - the first person in line gets served first.
• Implemented using singly linked lists (adding/removing from the beginning and end).
• Used for task scheduling, printer queues, and breadth-first search algorithms

Answer 81

Queues (FIFO - First In, First Out):

Question 82

is a fundamental concept in object-oriented programming (OOP) that allows you to create new classes based on existing ones.

Answer 82

Inheritance

Question 83

• Inheritance creates a relationship between classes, where a new class (subclass or derived class) inherits properties and behaviors from an existing class (superclass or base class).

Question 84

• Think of it as “is-a” relationship. For example, a Dog is-a Animal.

Question 85

Benefits of Inheritance:
* Code Reusability: You don’t need to rewrite code for common functionalities present in the superclass. The subclass inherits these functionalities and can add its own specific behavior.
* Maintainability: Changes made to the superclass automatically propagate to subclasses that inherit from it, making code updates easier.
* Polymorphism: Inheritance enables polymorphism, where objects of different subclasses can be treated as objects of the superclass. This allows for flexible and dynamic behavior in your programs.