Pattern matching for instanceof removes the cast

The binding variable is in scope only where the test succeeded, so the compiler guarantees the cast is safe.

Code

List<Object> values = List.of("java", 42, 3.5, List.of(1, 2));

for (Object o : values) {
    if (o instanceof String s && s.length() > 3) {
        System.out.println("long string: " + s.toUpperCase());
    } else if (o instanceof Integer i) {
        System.out.println("int doubled: " + (i * 2));
    } else if (o instanceof List<?> l) {
        System.out.println("list of size " + l.size());
    } else {
        System.out.println("other: " + o);
    }
}

Output

long string: JAVA
int doubled: 84
other: 3.5
list of size 2

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Published 2026-07-30