Java 21: Guarded patterns with when

Add a when clause to a switch case to refine matching with a boolean guard.

Code

Object obj = 150;
String size = switch (obj) {
    case Integer i when i < 100 -> "small";
    case Integer i when i < 1000 -> "medium";
    case Integer i -> "large";
    default -> "n/a";
};
System.out.println(size);

Output

medium

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Published 2026-07-26