[java] 옵셔널

import java.util.Optional;

public void optional() {

        // 옵셔널
        Optional<String> opt = Optional.ofNullable("자바 Optional 객체");

        System.out.println(opt.get());

        String str = null;
        Optional<String> opt2 = Optional.ofNullable(Optional.ofNullable(str)
        								.orElseGet(() -> str == null ? "fail" : "success"));

        System.out.println("opt2.isPresent() : " + opt2.isPresent());
        if(opt2.isPresent()) {
        	System.out.println(opt2.get());
        }}
}