Switch Expressions

A switch expression is a modern form of switch that produces a value you can assign or return, uses arrow labels with no fall-through, and is checked by the compiler for exhaustiveness.

Learn Switch Expressions in our free Java course — a beginner-friendly interactive lesson with worked examples, a practice exercise and a quick reference.

Part of the free Java course at LearnCodingFast — hands-on lessons with examples you run in your browser, plus practice exercises and a quick quiz.

Before You Start

You should know the classic switch statement and enums . Switch expressions are standard from Java 14 onward.

What You'll Learn

The Big Idea — A Vending Machine, Not a To-Do List

💡 Analogy: The old switch statement is a to-do list: "if it's Monday, do these chores; remember to stop ( break ) or you'll keep doing the next day's chores too." The new switch expression is a vending machine : you put in a value, press the matching button (an arrow arm), and it hands you back exactly one product. No risk of accidentally dispensing every snack below the one you wanted.

That single returned value is the whole point: String role = switch (rank) { ... } ; reads as one clear assignment instead of a mutable variable poked at by many case branches.

1️⃣ A switch That Returns a Value

Put the whole switch on the right of an assignment. Each arm uses case LABEL -> value; . The arrow makes each arm self-contained — there is no break , and no fall-through. Note the whole expression ends with a semicolon, just like any other assignment.

2️⃣ Block Arms, yield, and Exhaustive Enums

When an arm needs more than one statement, wrap it in braces and end with yield to supply the value — yield is the switch-expression equivalent of return . And when you switch over an enum and cover every constant, the switch is exhaustive , so you can drop default entirely.

3️⃣ Old Statement vs New Expression

Side by side, the difference is stark. The statement form needs a mutable label variable and a break after each case (forget one and you get a fall-through bug). The expression form assigns a value directly and can never fall through.

4️⃣ Multiple Labels & default

Group values that behave the same with a comma-separated label: case "GET", "HEAD" -> 200; . For open-ended types like String or int you still need a default arm so the switch stays exhaustive.

🧠 Quick Recall

Predict the result before opening each answer.

Answer: No — for an int input it is not exhaustive (what about 3, 4, ...?). error: the switch expression does not cover all possible input values . Add a default .

Answer: A block arm must return its value with yield v; , not break v; . break doesn't produce a value in a switch expression.

Answer: No. Arrow arms never fall through — TUE yields "two" and stops. Only the classic colon form (without break ) falls through.

🎯 Your Turn — Days in a month

Use a switch expression with a multi-label case to map a month number to its day count.

🧩 Mini-Challenge — Tag log levels

Cover every enum constant (so no default ) and use a block arm with yield for one of them.

Common Errors

• ❌ Forgetting the trailing semicolon. A switch expression assignment ends with ; . Fix: var x = switch(...) {...} ; .
• ❌ Using break value; in a block arm. Fix: use yield value; — only yield produces a value.
• ❌ Non-exhaustive switch over int/String. error: does not cover all possible input values . Fix: add a default arm.
• ❌ Mixing arrow and colon styles in one switch. Not allowed. Fix: pick one form for the whole switch.
• ❌ Expecting fall-through with arrows. There is none. Fix: list shared values in one label, e.g. case A, B -> ... .
• ❌ Adding default to an exhaustive enum switch unnecessarily. It silences the helpful error when a new constant is added. Fix: omit it so the compiler reminds you later.

Pro Tips

• 💡 Reach for switch expressions to replace if-else chains that compute one value — they're shorter and exhaustiveness-checked.
• 💡 Prefer enums as the switch subject. You get compile-time exhaustiveness for free and a warning when someone adds a constant.
• 💡 Keep arms tiny. If an arm grows large, extract a method and call it from the arm to keep the switch readable.
• 💡 Pair with assignment to final / var . The value is computed once and never reassigned — cleaner than a mutable accumulator.

📋 Quick Reference

Concept

Syntax

Note

Expression form

var x = switch (k) {...} ;

Produces a value

Arrow arm

case 1 -> "one";

No break, no fall-through

Multiple labels

case 1, 2, 3 -> ...

Share one arm

Block arm

case X -> { ... yield v; }

yield gives the value

Default

default -> ...;

Catches everything else

Enum exhaustive

all constants covered

default optional

Colon form value

case 1: yield x;

yield, not break

Switch on String

switch (s) {...}

Needs default

As a return

return switch (k) {...} ;

Common pattern

Statement form

switch (k) { case 1 -> act(); }

Arrows, no value

Since

Java 14

JEP 361

📚 Resources / Keep Learning

• 📘 Oracle: Switch Expressions and Statements — the official language guide.
• 📗 dev.java: Branching with switch — a guided tutorial.
• 📙 JEP 361: Switch Expressions — the finalizing proposal.

❓ Frequently Asked Questions

🎉 Lesson Complete!

You can now write a switch that returns a value, use arrow arms that never fall through, supply values from block arms with yield , group cases with multiple labels, and rely on exhaustiveness so an enum switch needs no default .

Next up: Pattern Matching — let instanceof and switch bind a typed variable for you.

Practice quiz

Continue this course

• Previous: Text Blocks
• Next: Pattern Matching

Related lessons

• switch statement
• enums