Pattern matching in switch

Code Comparison

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";
}

String format(Object obj) {
    return switch (obj) {
        case Integer i -> "int: " + i;
        case Double d  -> "double: " + d;
        case String s  -> "str: " + s;
        default        -> "unknown";
    };
}

Why the modern way wins

📐

Structured dispatch

Switch makes the branching structure explicit and scannable.

🎯

Expression form

Returns a value directly — no mutable variable needed.

✅

Exhaustiveness

The compiler ensures all types are handled.

Old Approach

if-else Chain

Modern Approach

Type Patterns

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.