可选ifPresent返回另一种类型

Question

使用java 8 Optional,有没有办法编写这行代码:

Bar bar = fooOpt.isPresent() ? new Bar(fooOpt.get().getX()) : null;

就像是:

Bar bar = fooOpt.ifPresent(f -> new Bar(f.getX()), null)

Answer 1

也许您正在寻找:

    Optional<Foo> fooOpt = ...
    Bar bar = fooOpt.map(foo -> new Bar(foo.getX()))
                    .orElse(null);

鉴于:

public class Foo {
    Object getX() {
        ...
    }
}

public class Bar {

    public Bar(Object x) {
        ...
    }
}