Switch Expressions and Statements

Lesson Overview

Programs often pick one action from several based on the exact value of something: a day name from a day number, an action from a menu option, a dashboard from a user role.

This can be written with if-else, but a long chain of option == 1, option == 2, … hides the fact that we are checking one value against a list. When checking several exact matches for the same value, switch is often more readable. Java has an older form with a well-known trap (fall-through) and a modern form that avoids it and can even produce a value; we will learn both, and when if-else is still the better tool.

Learning Objectives

After completing this lesson, you will be able to:

• Explain the purpose of switch
• Write a traditional switch
• Use case, default, and break
• Understand fall-through
• Write modern arrow-style switch
• Group multiple case labels
• Produce a value from a switch expression
• Use yield inside a block case
• Choose switch for exact matching and if-else for range-based logic

What Is switch?

switch is a control-flow structure. It evaluates a value and executes the matching case branch.

int dayNumber = 2;
switch (dayNumber) {
    case 1:
        System.out.println("Monday");
        break;

    case 2:
        System.out.println("Tuesday");
        break;

    default:
        System.out.println("Invalid day");
}

Output:

Tuesday

Here, the value of dayNumber is 2, so case 2: matches.

Basic Structure

Traditional syntax:

switch (value) {
    case firstValue:
        // Statements
        break;

    case secondValue:
        // Statements
        break;

    default:
        // Statements
}

• switch — determines which value is inspected
• case — defines a possible exact match
• break — exits the current switch
• default — executes when no case matches

Traditional switch

A menu example:

int option = 2;
switch (option) {
    case 1:
        System.out.println("Create course");
        break;

    case 2:
        System.out.println("View courses");
        break;

    case 3:
        System.out.println("Exit");
        break;

    default:
        System.out.println("Invalid option");
}

Output:

View courses

Each case, such as case 1: or case 2:, defines a possible matching value. If the switch value matches a case, execution begins from that branch. If no case matches (for example option = 9), the default branch executes and prints Invalid option.

default is not mandatory in every switch statement, but it is useful for handling unexpected values.

break and Fall-Through

In a traditional switch, break exits the switch after the matching branch has executed:

case 1:
    System.out.println("Monday");
    break;

Without break, execution can continue into the code of the following case. This behavior is called fall-through.

int option = 1;
switch (option) {
    case 1:
        System.out.println("One");

    case 2:
        System.out.println("Two");

    case 3:
        System.out.println("Three");

    default:
        System.out.println("Done");
}

Output:

One
Two
Three
Done

After case 1 matches, there is no break, so execution continues through the statements below it.

Accidental Fall-Through

Suppose:

int day = 2;
switch (day) {
    case 1:
        System.out.println("Monday");

    case 2:
        System.out.println("Tuesday");

    case 3:
        System.out.println("Wednesday");
}

The output will be:

Tuesday
Wednesday

If the expected output is only Tuesday, then this is a bug. When using traditional syntax, add the required break statements:

switch (day) {
    case 1:
        System.out.println("Monday");
        break;

    case 2:
        System.out.println("Tuesday");
        break;

    case 3:
        System.out.println("Wednesday");
        break;
}

Multiple Cases with the Same Action

In a traditional switch, several cases can share the same behavior. Here, case 6 and case 7 use the same code:

int day = 6;
switch (day) {
    case 6:
    case 7:
        System.out.println("Weekend");
        break;

    default:
        System.out.println("Weekday");
}

Output:

Weekend

Modern Arrow-Style switch

Since Java 14, and so in Java 21, we can use a cleaner arrow syntax for switch.

int day = 2;
switch (day) {
    case 1 -> System.out.println("Monday");
    case 2 -> System.out.println("Tuesday");
    case 3 -> System.out.println("Wednesday");
    default -> System.out.println("Invalid day");
}

Output:

Tuesday

Important advantages of arrow-style syntax:

• No automatic fall-through
• No break required
• Clearer branch structure

Multiple Case Labels

In an arrow-style switch, multiple values can be grouped using commas. This syntax is much clearer than traditional fall-through grouping.

int day = 6;
switch (day) {
    case 1, 2, 3, 4, 5 -> System.out.println("Weekday");
    case 6, 7 -> System.out.println("Weekend");
    default -> System.out.println("Invalid day");
}

Output:

Weekend

Multiple Statements in One Case

If an arrow case contains multiple statements, use a block. No break is required here either.

int option = 1;
switch (option) {
    case 1 -> {
        System.out.println("Creating course");
        System.out.println("Opening course form");
    }
    case 2 -> {
        System.out.println("Loading courses");
        System.out.println("Displaying course list");
    }
    default -> {
        System.out.println("Invalid option");
    }
}

Switch Statement vs. Switch Expression

So far, we have used switch to execute actions, such as printing a day name. This is a switch statement. In modern Java, switch can also produce a value. In that case, it is a switch expression. Here, the entire switch expression produces a String value:

int day = 3;
String dayName = switch (day) {
    case 1 -> "Monday";
    case 2 -> "Tuesday";
    case 3 -> "Wednesday";
    case 4 -> "Thursday";
    case 5 -> "Friday";
    case 6 -> "Saturday";
    case 7 -> "Sunday";
    default -> "Invalid day";
};
System.out.println(dayName);

Output:

Wednesday

Why Is a Switch Expression Useful?

Traditional version:

String dayName;
switch (day) {
    case 1:
        dayName = "Monday";
        break;

    case 2:
        dayName = "Tuesday";
        break;

    default:
        dayName = "Invalid";
}

Switch expression:

String dayName = switch (day) {
    case 1 -> "Monday";
    case 2 -> "Tuesday";
    default -> "Invalid";
};

The second version is:

• Shorter
• Clearer about assignment
• Free from accidental fall-through
• Able to initialize the variable directly

Rules for Switch Expressions

Semicolon After a Switch Expression

A switch expression is part of an assignment statement, so it ends with a semicolon. If the final ; is omitted, there will be a compilation error.

String result = switch (option) {
    case 1 -> "Create";
    case 2 -> "Update";
    default -> "Unknown";
};

Every Path Must Produce a Value

The expression above produces a compatible String value from every possible branch.

A switch expression must be exhaustive: it must handle every possible value of the selector. For a type such as int or String, the cases cannot list every possible value, so a default branch is required. Without it, the code does not compile.

yield

Inside an arrow case block, yield is used to produce a value after executing multiple statements.

int option = 1;
String result = switch (option) {
    case 1 -> {
        System.out.println("Creating course");
        yield "Created";
    }
    case 2 -> {
        System.out.println("Updating course");
        yield "Updated";
    }
    default -> {
        System.out.println("Unknown option");
        yield "Unknown";
    }
};
System.out.println(result);

Output:

Creating course
Created

When Is yield Needed?

A simple expression such as case 1 -> "Create"; needs no yield. But with a block, yield is required to provide the value of the switch expression:

case 1 -> {
    System.out.println("Creating");
    yield "Create";
}

yield and return Are Not the Same

yield "Create"; only provides the value of the current switch expression, while return exits the entire method. They are different concepts.

Using switch with String

You can also switch on exact text values.

String role = "INSTRUCTOR";
switch (role) {
    case "ADMIN" -> System.out.println("Admin dashboard");
    case "INSTRUCTOR" -> System.out.println("Instructor dashboard");
    case "LEARNER" -> System.out.println("Learner dashboard");
    default -> System.out.println("Unknown role");
}

Output:

Instructor dashboard

String Matching Is Case-Sensitive

INSTRUCTOR and instructor are not the same value, so the user input instructor would reach default. Normalize input before switching on it: with String role = " instructor ".strip().toUpperCase();, the same switch prints Instructor dashboard.

Mapping with a Switch Expression

A switch expression is useful for mapping one exact value to another value.

String level = "BEGINNER";
String description = switch (level) {
    case "BEGINNER" -> "No previous experience required";
    case "INTERMEDIATE" -> "Basic programming knowledge required";
    case "ADVANCED" -> "Strong programming knowledge required";
    default -> "Unknown course level";
};
System.out.println(description);

Output:

No previous experience required

switch or if-else?

Both control program flow, but they are useful for different situations.

Use switch When

You need to select a branch based on an exact match of one value, for example:

Option = 1, 2, 3
Role = ADMIN, INSTRUCTOR, LEARNER
Status = DRAFT, PUBLISHED, ARCHIVED
Day = 1, 2, 3, ...

switch (role) {
    case "ADMIN" -> ...
    case "INSTRUCTOR" -> ...
    case "LEARNER" -> ...
}

Use if-else When

The logic depends on ranges or complex boolean expressions:

if (mark >= 80) {
    System.out.println("A");
} else if (mark >= 70) {
    System.out.println("B");
}

Another example:

if (age >= 18 && emailVerified && !accountBlocked) {
    System.out.println("Enrollment allowed");
}

Ranges Are Not Direct case Values

You cannot write:

switch (mark) {
    case mark >= 80:
}

Here, case is being used for exact matching. For range-based logic such as grades, the if-else chain shown above is clearer.

Decision Guide

Complete Interactive Example

import java.util.Scanner;

public class Main {

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

        System.out.println("1. Create course");
        System.out.println("2. View courses");
        System.out.println("3. Update course");
        System.out.println("4. Exit");
        System.out.print("Choose an option: ");
        int option = Integer.parseInt(scanner.nextLine().strip());

        String action = switch (option) {
            case 1 -> "Create course";
            case 2 -> "View courses";
            case 3 -> "Update course";
            case 4 -> "Exit";
            default -> "Invalid option";
        };

        System.out.println("Selected: " + action);

        scanner.close();
    }
}

Possible interaction:

1. Create course
2. View courses
3. Update course
4. Exit
Choose an option: 2
Selected: View courses

Predict the Result

Question 1

int day = 2;
switch (day) {
    case 1:
        System.out.println("Monday");
    case 2:
        System.out.println("Tuesday");
    case 3:
        System.out.println("Wednesday");
        break;
    default:
        System.out.println("Other day");
}

What does this print?

Answer

Tuesday
Wednesday

case 2 matches, and without a break execution falls through into case 3. The break there stops it before default.

Question 2

int day = 2;
switch (day) {
    case 1 -> System.out.println("Monday");
    case 2 -> System.out.println("Tuesday");
    case 3 -> System.out.println("Wednesday");
    default -> System.out.println("Other day");
}

What does this print?

Answer

Tuesday. Arrow-style cases never fall through, so no break is needed.

Question 3

int day = 2;
String name = switch (day) {
    case 1 -> "Monday";
    case 2 -> "Tuesday";
};
System.out.println(name);

Will it compile?

Answer

No: the switch expression does not cover all possible input values. A switch expression must produce a value for every possible int, so it needs a default case.

Question 4

String role = "Admin";
String access = switch (role) {
    case "admin" -> "Full access";
    case "student" -> "Course access";
    default -> "No access";
};
System.out.println(access);

What does this print?

Answer

No access. String cases are case-sensitive, so "Admin" does not match "admin". Normalize the value first, for example with role.toLowerCase().

Common Mistakes

Missing break in Traditional Switch

Wrong:

switch (option) {
    case 1:
        System.out.println("Create");

    case 2:
        System.out.println("Update");

    default:
        System.out.println("Unknown");
}

If option = 1, all three branches execute and print Create, Update and Unknown. Add a break to every case (as in Accidental Fall-Through above), or use arrow-style syntax, which never falls through.

Duplicate Case

Invalid:

switch (option) {
    case 1 -> System.out.println("Create");
    case 1 -> System.out.println("Update");
}

The same case value cannot be duplicated: the compiler reports duplicate case label.

Wrong Case Type

int option = 1;
switch (option) {
    case "1" -> System.out.println("One");
}

option is an integer, but the case value is a String. Correct:

case 1 -> System.out.println("One");

Missing yield in a Block Case

Wrong:

String result = switch (option) {
    case 1 -> {
        System.out.println("Creating");
    }
    default -> "Unknown";
};

A branch of a switch expression must produce a value. Correct:

String result = switch (option) {
    case 1 -> {
        System.out.println("Creating");
        yield "Create";
    }
    default -> "Unknown";
};

Practice Exercise 1: Day Name

Solutions: lesson 1.24.

Use a day number:

1 → Monday
2 → Tuesday
3 → Wednesday
4 → Thursday
5 → Friday
6 → Saturday
7 → Sunday

Handle invalid values.

Practice Exercise 2: Weekday or Weekend

Map 1–5 to Weekday and 6–7 to Weekend. Use multiple case labels and a switch expression.

Practice Exercise 3: Menu

Menu:

1. Create course
2. View courses
3. Update course
4. Exit

Print the action based on the selected option.

Practice Exercise 4: Grade Description

Use a char value:

A → Excellent
B → Very good
C → Good
D → Needs improvement
F → Failed

Create the description using a switch expression.

Practice Exercise 5: Role

The possible values are ADMIN, INSTRUCTOR and LEARNER. Normalize the input and return the appropriate dashboard name.

Practice Exercise 6: Traditional to Arrow Style

Rewrite:

switch (option) {
    case 1:
        System.out.println("Create");
        break;

    case 2:
        System.out.println("Update");
        break;

    default:
        System.out.println("Unknown");
}

Practice Exercise 7: yield

Write a switch expression where one case:

1. Prints a message
2. yields a String value from the block

Practice Exercise 8: switch or if-else?

Choose the appropriate structure for each situation:

1. Age is 18 or above
2. Menu option 1–4
3. Grade from a mark
4. User role
5. Email verified and account active
6. Day number

Knowledge Check

Question 1

When is switch useful?

Question 2

What is a case?

Question 3

When does default execute?

Question 4

Why is break used in a traditional switch?

Question 5

What is fall-through?

Question 6

Is break required in an arrow-style switch?

Question 7

How can multiple case labels be written?

Question 8

What is the difference between a switch statement and a switch expression?

Question 9

Does a switch expression require a semicolon at the end?

Question 10

When is yield used?

Question 11

Is String switching case-sensitive?

Question 12

Which is generally more suitable for exact value matching: switch or if-else?

Question 13

Which is generally more suitable for numeric ranges?

Question 14

Are duplicate case values valid?

Knowledge Check Answers

Answer 1

switch is useful when selecting one branch from multiple branches based on an exact match of a value.

Answer 2

A case defines a possible matching value and its branch.

Answer 3

When no case matches.

Answer 4

To exit the switch after the matching branch and prevent unwanted fall-through.

Answer 5

Fall-through means execution continues into the code of following cases after a matching case.

Answer 6

No.

Answer 7

Separate them with commas: case 1, 2, 3 -> ...

Answer 8

A switch statement executes an action. A switch expression can produce a value.

Answer 9

Yes.

String result = switch (...) {
    // cases
};

Answer 10

yield is used to produce a value from a block-style case in a switch expression.

Answer 11

Yes.

Answer 12

switch.

Answer 13

if-else.

Answer 14

No.

Lesson Summary

• switch selects a branch based on an exact match of one value, and default handles values that no case matches.
• In a traditional switch, break exits the switch. Without it, execution falls through into the following cases.
• Arrow-style cases (->) do not fall through and need no break.
• Group several values in one arrow case with commas: case 6, 7 -> ....
• A switch expression produces a value, ends with a semicolon, and must handle every possible value, usually with default.
• Use yield to produce a value from a block case in a switch expression.
• Normalize String input before switching on it, because String matching is case-sensitive.
• Use switch for exact values and if-else for ranges and complex conditions.