Optional JDK8 判空新写法

/**
 * @author : zanglikun
 * @date : 2/22/24 16:36
 * @desc : Copyright © zanglikun.com
 */
public class TestOptional {
    @Data
    @AllArgsConstructor
    static class A {
        private B b;
    }

    @Data
    @AllArgsConstructor
    static class B {
        private C c;
    }

    @Data
    @AllArgsConstructor
    static class C {
        private String word;
    }

    public static void main(String[] args) {
        A a = new A(new B(new C("我是C的字符串")));
        // 如果我要去拿C的字符串如何拿？
        if (Objects.nonNull(a)) {
            if (Objects.nonNull(a.getB())) {
                if (Objects.nonNull(a.getB().getC())) {
                    String word = a.getB().getC().getWord();
                    System.out.println(word);
                }
            }
        }

        // 新式写法
        Optional<String> optional = Optional.of(a)
                .map(A::getB)
                .map(B::getC)
                .map(C::getWord);
        if (optional.isPresent()) {
            System.out.println(optional.get());
        }
    }
}