The instanceof operator tests whether an object is an instance of a type. Before pattern matching, a test was usually followed by a cast: if (obj instanceof String) { String s = (String) obj; ... }. Pattern matching combines the test, the cast and the variable declaration: if (obj instanceof String s) { ... }. If the test succeeds, s is a String variable ready to use. If obj is null, instanceof is false and nothing is bound.
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