Switch expressions

Switch as an expression that returns a value — no break, no fall-through.

Code Comparison

✕ Java 8

String msg;
switch (day) {
    case MONDAY:
        msg = "Start";
        break;
    case FRIDAY:
        msg = "End";
        break;
    default:
        msg = "Mid";
}

✓ Java 14+

String msg = switch (day) {
    case MONDAY  -> "Start";
    case FRIDAY  -> "End";
    default      -> "Mid";
};

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Why the modern way wins

🎯

Returns a value

Assign the switch result directly — no temporary variable needed.

🛡️

No fall-through

Arrow syntax eliminates accidental fall-through bugs from missing break.

✅

Exhaustiveness check

The compiler ensures all cases are covered.

Old Approach

Switch Statement

Modern Approach

Switch Expression

Since JDK

Difficulty

Beginner

JDK Support

Switch expressions

Available

Widely available since JDK 14 (March 2020)

How it works

Switch expressions return a value directly, use arrow syntax to prevent fall-through bugs, and the compiler verifies exhaustiveness. This replaces the error-prone statement form.

Compact source files

Java 8

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println(
            "Hello, World!");
    }
}

Java 25

void main() {
    IO.println("Hello, World!");
}

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JDK 25+ →

Language Intermediate

Sealed classes for type hierarchies

Java 8

// Anyone can extend Shape
public abstract class Shape { }
public class Circle extends Shape { }
public class Rect extends Shape { }
// unknown subclasses possible

Java 17+

public sealed interface Shape
    permits Circle, Rect {}
public record Circle(double r)
    implements Shape {}
public record Rect(double w, double h)
    implements Shape {}

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JDK 17+ →

Language Intermediate

Record patterns (destructuring)

Java 8

if (obj instanceof Point) {
    Point p = (Point) obj;
    int x = p.getX();
    int y = p.getY();
    System.out.println(x + y);
}

Java 21+

if (obj instanceof Point(int x, int y)) {
    IO.println(x + y);
}

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JDK 21+ →