Control Flow in Java

- July 18, 2025

Chapter 5: Control Flow in Java

Control flow in Java refers to the order in which instructions, statements, and function calls are executed or evaluated. Java provides several mechanisms to control the flow of execution through the program:

🧩 1. Conditional Statements

Conditional statements execute different blocks of code based on certain conditions.

🔸 if Statement


int number = 10;
if (number > 5) {
    System.out.println("Number is greater than 5");
}

🔸 if-else Statement


int number = 4;
if (number > 5) {
    System.out.println("Greater than 5");
} else {
    System.out.println("Less than or equal to 5");
}

🔸 if-else-if Ladder


int score = 85;
if (score >= 90) {
    System.out.println("Grade A");
} else if (score >= 80) {
    System.out.println("Grade B");
} else {
    System.out.println("Grade C");
}

🧩 2. switch Statement

The switch statement allows a variable to be tested for equality against multiple values.


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");
}

🔁 3. Looping Statements

Loops are used to execute a block of code repeatedly until a condition is met.

🔸 while Loop


int i = 0;
while (i < 5) {
    System.out.println(i);
    i++;
}

🔸 do-while Loop


int i = 0;
do {
    System.out.println(i);
    i++;
} while (i < 5);

🔸 for Loop


for (int i = 0; i < 5; i++) {
    System.out.println(i);
}

🔸 Enhanced for Loop (for-each)


int[] numbers = {1, 2, 3, 4};
for (int num : numbers) {
    System.out.println(num);
}

🛑 4. Control Flow Keywords

🔸 break Statement

Used to exit a loop or switch block prematurely.


for (int i = 0; i < 10; i++) {
    if (i == 5) break;
    System.out.println(i);
}

🔸 continue Statement

Skips the current iteration and continues with the next iteration of the loop.


for (int i = 0; i < 5; i++) {
    if (i == 2) continue;
    System.out.println(i);
}

🔸 return Statement

Ends the execution of the current method and optionally returns a value.


public int sum(int a, int b) {
    return a + b;
}

📘 Chapter Summary

if/else: Used for decision making
switch: Multiple condition branching
Loops: Repetitive execution
break/continue: Modify loop behavior
return: Exit from method

❓ FAQs with Answers

Q1: What is the difference between if-else and switch?

A: if-else can handle ranges and complex conditions, while switch is used for fixed values. Use switch for better readability with many fixed cases.

Q2: What is the use of break in loops?

A: break immediately exits the loop or switch statement where it is present, skipping the remaining iterations.

Q3: What is the difference between while and do-while loop?

A: while checks condition before execution, do-while executes at least once regardless of the condition.

Q4: What is the use of continue?

A: continue skips the current iteration and proceeds to the next loop cycle.

Q5: When should we use return?

A: return is used to exit a method and optionally return a value to the calling method.

Q6: What is an enhanced for loop in Java?

A: It is a simplified for loop used for arrays or collections where index manipulation is not needed.

Q7: Can break be used outside of loops or switch?

A: No, break must be used inside loops or switch statements only.

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