Conditional Statements

tags: Control Statements

What are conditional statements in Java?

• Conditional statements allow Java programs to make decisions based on boolean expressions.
• They control the flow of execution depending on whether a condition is true or false.

What are the main types of conditional statements in Java?

• if statement
• if-else statement
• if-else if ladder
• switch statement
• Ternary operator (?:)

How does an if statement work in Java?

An if statement checks a condition and executes the block only if the condition is true.

if (x > 0) {
    System.out.println("Positive number");
}

What is the syntax of the if-else statement?

The if-else allows choosing between two blocks.

if (x % 2 == 0) {
    System.out.println("Even");
} else {
    System.out.println("Odd");
}

What is an if-else-if ladder?

Used when there are multiple conditions to check.

if (score >= 90) {
    System.out.println("Grade A");
} else if (score >= 75) {
    System.out.println("Grade B");
} else {
    System.out.println("Grade C");
}

What is the switch statement used for?

The switch statement allows selecting one block to run from multiple cases, based on the value of an expression.

int day = 2;
switch (day) {
    case 1: System.out.println("Monday"); break;
    case 2: System.out.println("Tuesday"); break;
    default: System.out.println("Invalid day");
}

---

Which data types can be used in a switch statement in Java?

• byte, short, int, char
• String (Java 7 onwards)
• enum
• Wrapper types like Integer, Character

Note: boolean conditions cannot be used in a switch statement.

What happens if you forget break in a switch statement?

Without break, fall-through occurs — execution continues into the next case.

int x = 1;
switch (x) {
    case 1: System.out.println("One");
    case 2: System.out.println("Two"); // This will also run
}

What is the ternary operator in Java?

It is a compact version of if-else. It returns one of two values based on the condition.

int max = (a > b) ? a : b;

What are nested if statements?

An if inside another if. Used for multi-level decisions.

if (x > 0) {
    if (x % 2 == 0) {
        System.out.println("Positive Even");
    }
}

What are the rules for writing conditional expressions?

• The condition inside if must be boolean
• Use {} braces to avoid bugs even for single-line blocks
• Avoid deep nesting for better readability

Can a switch statement have duplicate case values?

No. Duplicate case values will cause a compile-time error.

Can default come before case in a switch block?

Yes. The position of default does not matter, but it’s conventionally written at the end.

What is short-circuiting in Java conditions?

In conditions using && or ||:

• A && B: if A is false, B is not evaluated
• A || B: if A is true, B is not evaluated

This improves performance and avoids unnecessary operations.