java - Generic Method to Get Optional Item from Map -


in java 8, i'm trying define generic method whether map<k, v> contains k key:

private static optional<v> find(final map<k, v> map, final k key) {     final v result = map.get(key);     return (result == null) ? optional.empty() : optional.of(key); }

but bunch of compile-time errors on k , v:

[error] ... compilation failure: [error] ~/app.java:[31,47] cannot find symbol [error] symbol:   class k [error] location: class com.myapp.app.app [error] ~/app.java:[31,50] cannot find symbol [error] symbol:   class v [error] location: class com.myapp.app.app

how can resolve these errors?

private static <k, v> optional<v> find(final map<k, v> map, final k key) {     final v result = map.get(key);     return optional.ofnullable(result); }

credit - sotirios delimanolis mentioning option#ofnullable , failure list generic parameters.


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