chapter 4

Question 1

Do programmers type code as fast as 100 words per minute?

Answer 1

No, programming is tedious. You must check for mistakes while writing and test the code multiple times.

Question 2

Is learning programming difficult?

Answer 2

No, but it requires patience and step-by-step learning.

Question 3

Is writing and running a Java program a lot of work?

Answer 3

Yes. Even displaying a simple sentence requires extra lines of code.

Question 4

How is Java different from English?

Answer 4

Java is for communicating with computers; English is for humans. Java is easier since computers don’t understand English.

Question 5

What are Java keywords?

Answer 5

Words with a fixed meaning that never changes across programs.

Question 6

Is Java case-sensitive?

Answer 6

Yes, but identifiers (names for variables, methods, etc.) are not.

Question 7

How many keywords are in Java?

Answer 7

50. const and goto exist but are unused.

Question 8

Which words look like keywords but aren’t?

Answer 8

true, false, null are not keywords.

Question 9

Can you redefine a keyword?

Answer 9

No. Keywords are set by Oracle and cannot be used as identifiers.

Question 10

What is an identifier?

Answer 10

A name used to label something in a program.

Question 11

What happens if you change an identifier name?

Answer 11

Only the name changes, but modifying standard API names can confuse other programmers.

Question 12

What is the standard API?

Answer 12

A list of commonly used identifier names in Java.

Question 13

What is a literal?

Answer 13

A fixed value (like a number or text) written directly in code.

Question 14

How do you write large numbers clearly in Java?

Answer 14

Use underscores (e.g., 1_000_000.00).

Question 15

How do number separators vary in Java?

Answer 15

Different regions use commas, underscores, or no separators at all.

Question 16

Why is punctuation important in Java?

Answer 16

Every bracket, brace, and symbol has a role in making code functional.

Question 17

What is indentation in Java?

Answer 17

Indentation makes code structure clear by showing hierarchy.

Question 18

How do curly braces relate to indentation?

Answer 18

They act like ‘boxes’ that group related code together.

Question 19

How can Eclipse auto-indent code?

Answer 19

Select the Java file, then go to Source > Format in the menu.

Question 20

What is a comment in Java?

Answer 20

A note for programmers that the computer ignores.

Question 21

Why use comments?

Answer 21

Helps programmers remember their code when revisiting later.

Question 22

What is a traditional comment?

Answer 22

A comment enclosed in /* … */. Extra * can be added for neat formatting.

Question 23

What is an end-of-line comment in Java?

Answer 23

An end-of-line comment starts with two slashes (//) and extends to the end of the line.

Question 24

How do you switch off parts of your program without deleting code?

Answer 24

Comment out the code; it’s like turning it on/off by adding/removing the comment symbols.

Question 25

What is a Javadoc comment?

Answer 25

A Javadoc comment starts with /** and helps generate documentation for your code using Oracle’s Javadoc tool.

Question 26

What is a Java method?

Answer 26

A Java method is a block of code with a name that performs a specific task when called.

Question 27

What is a method declaration?

Answer 27

It’s the method's signature, including the name and parameters (if any), followed by the method body enclosed in curly braces.

Question 28

What is a method call?

Answer 28

A method call invokes the method to execute its instructions.

Question 29

What can be said about calling the main method into action?

Answer 29

The main method is called automatically when the program runs.

Question 30

When are instructions in a method executed?

Answer 30

When the method is called. If it's main, it's called automatically.

Question 31

Can a statement also be a method call?

Answer 31

Yes. Example: System.out.println("Hello"); is both a method call and a statement.

Question 32

What symbol ends every statement in Java?

Answer 32

A semicolon ;.

Question 33

Why do some call OOP 'Class-Oriented Programming'?

Answer 33

Because everything in Java is written inside a class.

Question 34

What is the purpose of curly braces {}?

Answer 34

To mark where a block of code starts and ends, interpreted by the computer

Question 35

Why do we indent code?

Answer 35

To make code easier for humans to read and follow.

Question 36

What symbols must be used to properly indent and structure code?

Answer 36

Curly braces {} for blocks, and spaces/tabs for visual indentation.

Question 37

What is an escape sequence in Java?

Answer 37

A special character preceded by a backslash (\) used to represent characters that can’t be typed directly into a string.

Question 38

What does the escape sequence \" do?

Answer 38

Inserts a double quote (") inside a string.

Question 39

What does the escape sequence \' do?

Answer 39

Inserts a single quote (') inside a string.

Question 40

What does the escape sequence \\ do?

Answer 40

Inserts a backslash (\) into the string.

Question 41

What does the escape sequence \n do?

Answer 41

Moves the output to a new line (newline).

Question 42

What does the escape sequence \t do?

Answer 42

Inserts a horizontal tab (adds spacing).

Question 43

What are the rules for creating valid identifier names in Java?

Answer 43

Follow these rules to create valid identifier names in Java: ✅ Must start with a letter (A–Z or a–z), an underscore (_) or dollar sign ($). ✅ Can contain letters, digits (0–9), underscores, and dollar signs after the first character. ❌ Cannot start with a digit (e.g., 7name is invalid). ❌ Cannot contain spaces or special characters like @, #, /, or -. ❌ Cannot use reserved keywords (e.g., public, class, static, etc.). ✅ Java is case-sensitive (myVar ≠ MyVar).