Chapter 3

Question 1

What does an if statement do?

Answer 1

It decides whether a section of code executes based on a condition.

Question 2

What is the syntax for an if statement?

Answer 2

if (boolean expression)
statement;

Question 3

What happens if an if statement doesn’t use curly braces?

Answer 3

Only the first statement after the if condition is executed conditionally.

Question 4

How do you group multiple statements in an if block?

Answer 4

Use curly braces {} to enclose the statements.
Example:

if (x > 0) {
System.out.println(“Positive”);
System.out.println(“Greater than zero”);
}

Question 5

What is a flag?

Answer 5

A boolean variable that monitors a condition in a program.

Question 6

How can characters be compared in Java?

Answer 6

Characters can be compared using relational operators because they are stored as Unicode values.
Example:

if (‘A’ < ‘Z’)
System.out.println(“A comes before Z”);

Question 7

What does an if-else statement do?

Answer 7

Executes one block of code if the condition is true and another block if the condition is false.
Syntax:

if (condition)
statement1;
else
statement2;

Question 8

What is a nested if statement?

Answer 8

An if statement inside another if statement.

Question 9

How does an if-else-if statement work?

Answer 9

It simplifies multiple decision branches.
Syntax:

if (condition1)
statement1;
else if (condition2)
statement2;
else
statement3;

Question 10

What are the three logical operators in Java?

Answer 10

Logical AND (&&)
Logical OR (||)
Logical NOT (!)

Question 11

When does && evaluate to true?

Answer 11

When both operands are true.

Question 12

When does || evaluate to true?

Answer 12

When at least one operand is true.

Question 13

What does the ! operator do?

Answer 13

It negates the truth value of a boolean expression.
Example:

if (!(temperature > 100))
System.out.println(“Below max temperature”);

Question 14

What is short-circuit evaluation?

Answer 14

&& stops evaluating as soon as one operand is false.
|| stops evaluating as soon as one operand is true.

Question 15

Can relational operators compare two String objects?

Answer 15

No, use methods like equals or compareTo.

Question 16

What is the syntax of the conditional (ternary) operator?

Answer 16

BooleanExpression ? Value1 : Value2;
Example:

int number = x > y ? 10 : 5;

Question 17

What is the scope of a local variable?

Answer 17

From the point of its declaration to the end of the method in which it is declared.

Question 18

How does the equalsIgnoreCase method work with strings?

Answer 18

It compares two String objects while ignoring case differences.

Question 19

What is the purpose of the if-else statement in Java?

Answer 19

It is used for branching based on a true/false condition.

Question 20

What data types can the SwitchExpression in a switch statement evaluate?

Answer 20

byte, short, int, long, char, or String (Java 7+

Question 21

True or False: Each CaseExpression in a switch statement must be unique.

Answer 21

Each case must have a unique value.

Question 22

What happens if a break statement is omitted in a switch case?

Answer 22

Execution will “fall through” to the next case.

Question 23

How do you define the default section in a switch statement?

Answer 23

Use the default keyword to specify the code that executes when no case matches:

default:
// statements

Question 24

Write an example of using a switch with String values.

Answer 24

switch (color) {
case “red”:
System.out.println(“Red selected”);
break;
case “blue”:
System.out.println(“Blue selected”);
break;
default:
System.out.println(“No match”);
}

Question 25

What is the syntax of the System.out.printf method?

Answer 25

System.out.printf(FormatString, ArgList);

Question 26

What does the String.format method do differently than System.out.printf?

Answer 26

It returns the formatted string instead of displaying it on the console.

Question 27

Write an example of using String.format to store a formatted string.

Answer 27

String message = String.format("Name: %s Age: %d", "Alice", 25); System.out.println(message);

Question 28

What is the purpose of the default case in a switch statement?

Answer 28

The default case executes when no CaseExpression matches the SwitchExpression.

Question 29

What will this code output if choice = 1? switch (choice) { case 1: System.out.println("Choice 1"); case 2: System.out.println("Choice 2"); default: System.out.println("Default choice"); }

Answer 29

Output: Choice 1 Choice 2 Default choice The break statements are missing, so the cases fall through.

Question 30

True or False: A switch statement can evaluate floating-point numbers like float or double.

Answer 30

switch cannot evaluate floating-point numbers. It only works with ordinal types like int, char, and String.

Question 31

What is the purpose of formatted output in Java?

Answer 31

To control the appearance of the output, such as alignment, decimal precision, or padding.