从Java返回可选的ifPresent() [英] Returning from Java Optional ifPresent()

问题描述

我知道您无法从ifPresent()返回，因此此示例不起作用:

I understand you can't return from a ifPresent() so this example does not work:

public boolean checkSomethingIfPresent() {
    mightReturnAString().ifPresent((item) -> {
        if (item.equals("something")) {
            // Do some other stuff like use "something" in API calls
            return true; // Does not compile
        }
    });
    return false;
}

mightReturnAString() 可以的地方，返回有效的字符串或空的可选字符.我所做的工作是:

Where mightReturnAString() could return a valid string or an empty optional. What I have done that works is:

public boolean checkSomethingIsPresent() {
    Optional<String> result = mightReturnAString();

    if (result.isPresent()) {
        String item = result.get();
        if (item.equals("something") {
            // Do some other stuff like use "something" in API calls
            return true;
        }
    }
    return false;
}

，它更长，并且与仅检查空值没有太大区别.我觉得使用Optional必须有更简洁的方法.

which is longer and does not feel much different to just checking for nulls in the first place. I feel like there must be a more succinct way using Optional.

推荐答案

我认为您正在寻找的只是filter并检查是否存在:

I think all you're looking for is simply filter and check for the presence then:

return result.filter(a -> a.equals("something")).isPresent();

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