Weeks 1-4; Elementary, Conditionals, Loops

Question 1

What are the two types of Java programs?

Answer 1

Applications: Standalone programs. Applets: Require a Java-enabled browser to run.

Question 2

What are the three looping structures in Java?

Answer 2

while (pre-test loop), do-while (post-test loop), for (pre-test loop with control).

Question 3

What is the difference between while and do-while?

Answer 3

while tests the condition first; do-while executes at least once before testing.

Question 4

How do you structure a basic if statement?

Answer 4

An if statement checks a condition, and if it is true, executes a block of statements.

Question 5

How do you structure a for loop?

Answer 5

A for loop combines initialization, condition check, and update in one line.

Question 6

What is a flag in Java?

Answer 6

A boolean variable that monitors a condition in a program, e.g., boolean highScore.

Question 7

How do you generate a random number in Java?

Answer 7

Use the Random class and methods like nextInt() or nextDouble() to generate numbers.

Question 8

How are comments written in Java?

Answer 8

Single-line: // comment; Multi-line: /* comment /; Javadoc: /* comment */.

Question 9

What is the purpose of the break statement?

Answer 9

Terminates a loop prematurely.

Question 10

What is the purpose of the continue statement?

Answer 10

Skips the current iteration and moves to the next iteration.

Question 11

How are strings compared in Java?

Answer 11

Use .equals(), .equalsIgnoreCase() for equality; .compareTo() for lexicographical order.

Question 12

What is the syntax for a switch statement?

Answer 12

A switch statement evaluates a value and matches it against multiple cases for execution.

Question 13

How do you create a constant in Java?

Answer 13

Use the final keyword to declare a constant value that cannot change.

Question 14

How is input validated using a loop?

Answer 14

Use a while loop to repeatedly prompt the user until valid input is entered.

Question 15

What is the purpose of curly braces {} in loops?

Answer 15

To group multiple statements into a block to execute together.

Question 16

What are escape sequences in Java?

Answer 16

Examples: \n (newline), \t (tab), \ (backslash), “ (double quote).

Question 17

What is the purpose of the Scanner class?

Answer 17

To read input from the user using methods like nextInt() or nextLine().

Question 18

What are the three parts of a for loop?

Answer 18

Initialization: Sets the control variable. Condition: Tests the loop variable. Update: Modifies the control variable.

Question 19

What is a sentinel value?

Answer 19

A special value indicating the end of input, e.g., -1 in a list of positive numbers.

Question 20

What is the ternary operator?

Answer 20

A compact form of if-else: result = (condition) ? value1 : value2.

Question 21

What is the Random class used for?

Answer 21

To generate random numbers using methods like nextInt() and nextDouble().

Question 22

How is an infinite loop caused?

Answer 22

Forgetting to update the control variable or setting a condition that is always true.

Question 23

What is a nested loop?

Answer 23

A loop inside another loop where the inner loop completes all iterations for each outer loop iteration.

Question 24

What are Java reserved keywords?

Answer 24

Examples: abstract, class, void, static, if, else, while, etc.

Question 25

How are local variables scoped?

Answer 25

Scope begins at declaration and ends at the method’s closing brace.

Question 26

How do you concatenate strings in Java?

Answer 26

Use the + operator, e.g., "Hello " + "World".

Question 27

What are arithmetic operators in Java?

Answer 27

+, -, *, /, %

Question 28

What is integer division?

Answer 28

Division with two integers truncates the decimal part, e.g., 5 / 2 = 2.

Question 29

How does System.out.printf work?

Answer 29

Used for formatted output, allowing control over display of variables and text.

Question 30

What are relational operators?

Answer 30

>, <, >=, <=, ==, !=

Question 31

How do logical operators work?

Answer 31

&&: AND, ||: OR, !: NOT

Question 32

How is a string's length found?

Answer 32

Use the .length() method to retrieve the length of a string.

Question 33

What is a bytecode file?

Answer 33

A compiled Java file with .class extension, interpreted by the JVM.

Question 34

What are escape sequences for characters?

Answer 34

\n (newline), \t (tab), " (quote), \ (backslash).

Question 35

What is Object-Oriented Programming (OOP)?

Answer 35

A programming paradigm based on objects that encapsulate data and behavior.

Question 36

What are the four pillars of OOP?

Answer 36

Encapsulation, Inheritance, Polymorphism, and Abstraction.

Question 37

What is encapsulation in Java?

Answer 37

Bundling data (fields) and methods that operate on the data into a single unit (class).

Question 38

How is inheritance implemented in Java?

Answer 38

Using the extends keyword to create a subclass from a parent class.

Question 39

What is polymorphism in Java?

Answer 39

The ability of objects to take on multiple forms, such as method overriding or overloading.

Question 40

What is abstraction in Java?

Answer 40

Hiding complex implementation details and showing only essential features.

Question 41

What is a class in Java?

Answer 41

A blueprint for creating objects that encapsulate data and methods.

Question 42

What is an object in Java?

Answer 42

An instance of a class containing specific data and behavior.

Question 43

How do you create an object in Java?

Answer 43

Use the new keyword: ClassName obj = new ClassName();

Question 44

What are constructors in Java?

Answer 44

Special methods used to initialize new objects.

Question 45

What is method overloading?

Answer 45

Defining multiple methods with the same name but different parameter lists.

Question 46

What is method overriding?

Answer 46

Redefining a method in a subclass that already exists in the parent class.

Question 47

What is the difference between this and super?

Answer 47

this refers to the current object; super refers to the parent class.

Question 48

What are interfaces in Java?

Answer 48

A reference type that defines abstract methods a class must implement.

Question 49

How do abstract classes differ from interfaces?

Answer 49

Abstract classes can have implemented methods; interfaces cannot (prior to Java 8).

Question 50

What is the static keyword used for?

Answer 50

To declare class-level variables or methods shared among all objects of a class.

Question 51

What is a control statement in Java?

Answer 51

A statement that determines the flow of execution, e.g., if, for, while, switch.

Question 52

What is the difference between pre-test and post-test loops?

Answer 52

Pre-test loops (while, for) check the condition before executing; post-test loops (do-while) execute at least once.

Question 53

How is the order of precedence determined in Java?

Answer 53

Operators are evaluated in a specific order: ! > arithmetic > relational > logical.

Question 54

What are the types of errors in Java?

Answer 54

Syntax errors, runtime errors, and logical errors.

Question 55

What is short-circuit evaluation in logical operators?

Answer 55

Logical AND (&&) stops if the first condition is false; logical OR (||) stops if the first condition is true.

Question 56

What are flowcharts used for in programming?

Answer 56

To visually represent the flow of control in algorithms or program logic.