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Language Intermediate

Pattern matching in switch

Replace if-else instanceof chains with clean switch type patterns.

Code Comparison
โœ• Java 8 
String format(Object obj) {
    if (obj instanceof Integer i)
        return "int: " + i;
    else if (obj instanceof Double d)
        return "double: " + d;
    else if (obj instanceof String s)
        return "str: " + s;
    return "unknown";
}
โœ“ Java 21+ 
String format(Object obj) {
    return switch (obj) {
        case Integer i -> "int: " + i;
        case Double d  -> "double: " + d;
        case String s  -> "str: " + s;
        default        -> "unknown";
    };
}
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Why the modern way wins
๐Ÿ“

Structured dispatch

Switch makes the branching structure explicit and scannable.

๐ŸŽฏ

Expression form

Returns a value directly โ€” no mutable variable needed.

โœ…

Exhaustiveness

The compiler ensures all types are handled.

Old Approach
if-else Chain
Modern Approach
Type Patterns
Since JDK
21
Difficulty
Intermediate
JDK Support
Pattern matching in switch
Available

Widely available since JDK 21 LTS (Sept 2023)

How it works

Pattern matching in switch lets you match on types directly, combining the type test, cast, and binding in one concise case label. The compiler checks completeness.

Related Documentation
Pattern Matching for switch (JEP 441) โ†—
Proof
View proof source โ†—
Related patterns
Language Beginner

Pattern matching for instanceof

Java 8
if (obj instanceof String) {
    String s = (String) obj;
    System.out.println(s.length());
}
Java 16+
if (obj instanceof String s) {
    IO.println(s.length());
}
Hover to see modern โžœ
JDK 16+ โ†’
Language Beginner

Unnamed variables with _

Java 8
try {
    parse(input);
} catch (Exception ignored) {
    log("parse failed");
}
map.forEach((key, value) -> {
    process(value); // key unused
});
Java 22+
try {
    parse(input);
} catch (Exception _) {
    log("parse failed");
}
map.forEach((_, value) -> {
    process(value);
});
Hover to see modern โžœ
JDK 22+ โ†’
Language Beginner

Records for data classes

Java 8
public class Point {
    private final int x, y;
    public Point(int x, int y) { ... }
    public int getX() { return x; }
    public int getY() { return y; }
    // equals, hashCode, toString
}
Java 16+
public record Point(int x, int y) {}
Hover to see modern โžœ
JDK 16+ โ†’
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