Java switch case Statement

Java Switch-Case Statement Tutorial

In Java, the switch statement is a multi-branch control structure that allows you to choose a block of code to execute based on the value of a variable or expression. The switch statement is often used as an alternative to a series of nested if-else statements.

Basic Syntax:

The switch statement is followed by an expression in parentheses and a block of code enclosed in curly braces. Inside the block, you define case labels followed by a constant value and a colon. The break statement is used to exit the switch block after a matching case is executed.

switch (expression) {
    case constant1:
        // Code block to execute if expression == constant1
        break;
    case constant2:
        // Code block to execute if expression == constant2
        break;
    ...
    default:
        // Code block to execute if no matching case is found
}

Example:

public class Main {
    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;
            case 6:
                System.out.println("Saturday");
                break;
            case 7:
                System.out.println("Sunday");
                break;
            default:
                System.out.println("Invalid day");
        }
    }
}

Output:

Wednesday

Using switch with String and enum:

In addition to primitive types like int, char, and byte, Java supports using String and enum types in switch statements.

Example with String:

public class Main {
    public static void main(String[] args) {
        String day = "Tuesday";

        switch (day) {
            case "Monday":
                System.out.println("It's Monday");
                break;
            case "Tuesday":
                System.out.println("It's Tuesday");
                break;
            // ... other cases
            default:
                System.out.println("Invalid day");
        }
    }
}

Example with enum:

enum Weekday { MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY }

public class Main {
    public static void main(String[] args) {
        Weekday day = Weekday.WEDNESDAY;

        switch (day) {
            case MONDAY:
                System.out.println("It's Monday");
                break;
            case TUESDAY:
                System.out.println("It's Tuesday");
                break;
            // ... other cases
            default:
                System.out.println("Invalid day");
        }
    }
}

Using switch-case in Java: The switch statement is used to make decisions based on the value of an expression. It allows for multiple conditions to be evaluated in a more concise manner.

int dayOfWeek = 2;

switch (dayOfWeek) {
    case 1:
        System.out.println("Monday");
        break;
    case 2:
        System.out.println("Tuesday");
        break;
    // ... cases for other days
    default:
        System.out.println("Invalid day");
}

Switch statement with primitive types in Java: The switch statement can be used with byte, short, char, int, and their wrapper classes (Byte, Short, Character, Integer).

int number = 2;

switch (number) {
    case 1:
        System.out.println("One");
        break;
    case 2:
        System.out.println("Two");
        break;
    // ... other cases
}

Handling multiple cases in Java switch: Multiple cases can be handled by allowing them to fall through, or by grouping them using a common block.

int dayOfWeek = 2;

switch (dayOfWeek) {
    case 1:
    case 2:
    case 3:
    case 4:
    case 5:
        System.out.println("Weekday");
        break;
    case 6:
    case 7:
        System.out.println("Weekend");
        break;
    default:
        System.out.println("Invalid day");
}

Switch-case with enum in Java: Enums are often used with switch statements to represent a set of constant values.

enum Day {
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
}

Day day = Day.MONDAY;

switch (day) {
    case MONDAY:
        System.out.println("It's Monday!");
        break;
    // ... other cases
}

Nested switch statements in Java: Switch statements can be nested to handle complex scenarios where multiple conditions need to be evaluated.

int outerValue = 1;
int innerValue = 2;

switch (outerValue) {
    case 1:
        switch (innerValue) {
            case 1:
                System.out.println("Outer 1, Inner 1");
                break;
            case 2:
                System.out.println("Outer 1, Inner 2");
                break;
        }
        break;
    // ... other cases
}

String in switch statement in Java: Starting from Java 7, the switch statement supports String values.

String dayOfWeek = "Monday";

switch (dayOfWeek) {
    case "Monday":
        System.out.println("It's Monday!");
        break;
    // ... other cases
}

Default case in Java switch statement: The default case is executed when none of the preceding cases match the value of the expression.

int dayOfWeek = 8;

switch (dayOfWeek) {
    case 1:
        System.out.println("Monday");
        break;
    // ... other cases
    default:
        System.out.println("Invalid day");
}

Java switch-case and break statement: The break statement is used to exit the switch statement. Without it, execution would fall through to subsequent cases.

int dayOfWeek = 2;

switch (dayOfWeek) {
    case 1:
        System.out.println("Monday");
        break;
    case 2:
        System.out.println("Tuesday");
        // No break, falls through to the next case
    case 3:
        System.out.println("Wednesday");
        break;
    // ... other cases
}

Switch-case for char data type in Java: The switch statement can be used with the char data type.

char grade = 'A';

switch (grade) {
    case 'A':
        System.out.println("Excellent");
        break;
    // ... other cases
}

Switch statement for multiple conditions in Java: The switch statement is effective when there are multiple conditions based on the value of a variable.

int value = 2;

switch (value) {
    case 1:
        System.out.println("One");
        break;
    case 2:
        System.out.println("Two");
        break;
    // ... other cases
}