Java Switch Statement

The switch statement in Java is a control structure that lets you execute a block of code among multiple options. It is a cleaner alternative to multiple if-else-if conditions, making your code more readable and efficient.

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Syntax of Switch Statement

switch (expression) {
    case value1:
        // Code block for case 1
        break;
    case value2:
        // Code block for case 2
        break;
    // Add more cases as needed
    default:
        // Code block if none of the cases match
}

• expression: The value being tested (integer, string, or enum type).
• case value: A possible value for the expression.
• break: Stops the execution of the switch block.
• default: Executes if no cases match.

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Example 1: Basic Switch Statement

public class SwitchExample {
    public static void main(String[] args) {
        int day = 3;

        switch (day) {
            case 1:
                System.out.println("Monday");
                break;
            case 2:
                System.out.println("Tuesday");
                break;
            case 3:
                System.out.println("Wednesday");
                break;
            case 4:
                System.out.println("Thursday");
                break;
            case 5:
                System.out.println("Friday");
                break;
            default:
                System.out.println("Weekend");
        }
    }
}

Output:

Wednesday

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Real-Life Example: Grade System

public class GradeSystem {
    public static void main(String[] args) {
        char grade = 'B';

        switch (grade) {
            case 'A':
                System.out.println("Excellent!");
                break;
            case 'B':
                System.out.println("Well done!");
                break;
            case 'C':
                System.out.println("Good effort!");
                break;
            case 'D':
                System.out.println("You passed.");
                break;
            default:
                System.out.println("Invalid grade.");
        }
    }
}

Output:

Well done!

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Switch Without Break

If you omit the break statement, all cases after the matching one will execute until a break or the end of the switch block.

Example 3: Fall-Through Behavior

public class FallThroughExample {
    public static void main(String[] args) {
        int number = 2;

        switch (number) {
            case 1:
                System.out.println("One");
            case 2:
                System.out.println("Two");
            case 3:
                System.out.println("Three");
            default:
                System.out.println("Other number");
        }
    }
}

Output:

Two
Three
Other number

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Solution: Use break

public class BreakExample {
    public static void main(String[] args) {
        int number = 2;

        switch (number) {
            case 1:
                System.out.println("One");
                break;
            case 2:
                System.out.println("Two");
                break;
            case 3:
                System.out.println("Three");
                break;
            default:
                System.out.println("Other number");
        }
    }
}

Output:

Two

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Nested Switch

You can use a switch inside another switch for complex decision-making.

Example 4: Nested Switch Example

public class NestedSwitch {
    public static void main(String[] args) {
        String department = "Engineering";
        int year = 3;

        switch (department) {
            case "Engineering":
                switch (year) {
                    case 1:
                        System.out.println("Engineering, First Year");
                        break;
                    case 2:
                        System.out.println("Engineering, Second Year");
                        break;
                    case 3:
                        System.out.println("Engineering, Third Year");
                        break;
                }
                break;
            case "Arts":
                System.out.println("Arts Department");
                break;
            default:
                System.out.println("Invalid department.");
        }
    }
}

Output:

Engineering, Third Year

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Switch with Strings

Since Java 7, switch supports strings, which improves flexibility.

Example 5: String-Based Switch

public class StringSwitchExample {
    public static void main(String[] args) {
        String fruit = "Apple";

        switch (fruit) {
            case "Apple":
                System.out.println("It's red!");
                break;
            case "Banana":
                System.out.println("It's yellow!");
                break;
            case "Grapes":
                System.out.println("They're green or purple!");
                break;
            default:
                System.out.println("Unknown fruit.");
        }
    }
}

Output:

It's red!

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Switch vs. If-Else

Feature	Switch	If-Else
Readability	Easier with multiple conditions	Complex for many conditions
Data Types Supported	Limited (int, char, String, enums)	Supports all data types
Performance	Faster for many conditions	Slower due to multiple evaluations

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Real-Life Example: Menu-Driven Program

import java.util.Scanner;

public class MenuDrivenProgram {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.println("Menu:");
        System.out.println("1. Add");
        System.out.println("2. Subtract");
        System.out.println("3. Multiply");
        System.out.println("4. Divide");
        System.out.println("Choose an option:");

        int choice = sc.nextInt();
        System.out.println("Enter two numbers:");
        int a = sc.nextInt();
        int b = sc.nextInt();

        switch (choice) {
            case 1:
                System.out.println("Result: " + (a + b));
                break;
            case 2:
                System.out.println("Result: " + (a - b));
                break;
            case 3:
                System.out.println("Result: " + (a * b));
                break;
            case 4:
                System.out.println("Result: " + (a / b));
                break;
            default:
                System.out.println("Invalid choice.");
        }

        sc.close();
    }
}

Output Example:

Menu:
1. Add
2. Subtract
3. Multiply
4. Divide
Choose an option:
3
Enter two numbers:
6
7
Result: 42

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By mastering the switch statement, you can simplify decision-making in your Java programs, making them cleaner and more efficient.