1. Introduction to Control Flow

1.1 What are Control Flow Statements

Control flow statements determine the order in which code is executed.

1.2 Importance

They help in:

• Decision making
• Repeating tasks
• Controlling execution path

1.3 Types

• Conditional statements
• Looping statements
• Jump statements

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2. Conditional Statements

2.1 Overview

Conditional statements are used to execute code based on conditions.

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2.2 if Statement

Syntax

if (condition) {
    // code
}

Example

int age = 20;
if (age > 18) {
    System.out.println("Adult");
}

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2.3 if-else Statement

Syntax

if (condition) {
    // true block
} else {
    // false block
}

Example

int num = 5;
if (num % 2 == 0) {
    System.out.println("Even");
} else {
    System.out.println("Odd");
}

if-else-if Ladder

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

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2.4 Nested if Statements

Definition

An if statement inside another if statement.

Example

int age = 20;
boolean hasID = true;if (age > 18) {
    if (hasID) {
        System.out.println("Allowed");
    }
}

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2.5 switch Statement

Syntax

switch (value) {
    case 1:
        // code
        break;
    case 2:
        // code
        break;
    default:
        // code
}

Example

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

Key Points

• Uses break to stop execution
• default executes if no case matches

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3. Looping Statements

3.1 Introduction

Loops are used to repeat a block of code multiple times.

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3.2 for Loop

Syntax

for (initialization; condition; update) {
    // code
}

Example

for (int i = 1; i <= 5; i++) {
    System.out.println(i);
}

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3.3 while Loop

Syntax

while (condition) {
    // code
}

Example

int i = 1;while (i <= 5) {
    System.out.println(i);
    i++;
}

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3.4 do-while Loop

Syntax

do {
    // code
} while (condition);

Example

int i = 1;do {
    System.out.println(i);
    i++;
} while (i <= 5);

Difference

• Executes at least once

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3.5 Enhanced for Loop

Syntax

for (type variable : array) {
    // code
}

Example

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

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4. Jump Statements

4.1 Introduction

Jump statements alter the normal flow of loops and methods.

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4.2 break Statement

Definition

Terminates the loop immediately.

Example

for (int i = 1; i <= 5; i++) {
    if (i == 3) {
        break;
    }
    System.out.println(i);
}

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4.3 continue Statement

Definition

Skips the current iteration.

Example

for (int i = 1; i <= 5; i++) {
    if (i == 3) {
        continue;
    }
    System.out.println(i);
}

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4.4 return Statement

Definition

Exits from a method.

Example

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

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Conclusion

Control flow statements are essential for building logical and interactive Java programs. By mastering conditional statements, loops, and jump statements, you can control how your program behaves and responds to different situations. These concepts form the foundation for solving real-world programming problems.