Pattern matching: guarded patterns with when

A when clause adds a condition to a pattern label, which replaces nested if statements inside each case.

Code

sealed interface Payment permits Card, Upi {}
record Card(int amount) implements Payment {}
record Upi(int amount) implements Payment {}

List<Payment> payments = List.of(new Card(50), new Card(5000), new Upi(200));

for (Payment p : payments) {
    String route = switch (p) {
        case Card c when c.amount() > 1000 -> "card " + c.amount() + " -> manual review";
        case Card c -> "card " + c.amount() + " -> auto approve";
        case Upi u -> "upi " + u.amount() + " -> instant";
    };
    System.out.println(route);
}

Output

card 50 -> auto approve
card 5000 -> manual review
upi 200 -> instant

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Published 2026-07-30