Java可选-如果其他语句

问题描述

所以，看完书后，我已经看到了

So after some reading I've seen that

if (optional.isPresent()) {
    //do smth
}

不是使用Optional的首选方式( http://www.oracle.com/technetwork/articles/java/java8-optional-2175753.html ).但是，如果我有这样的if语句:

is not the preferred way to use Optional (http://www.oracle.com/technetwork/articles/java/java8-optional-2175753.html). But if I have an if-statement like this:

if (optional.isPresent()) {
    car = getCar(optional.get());
} else {
    car = new Car();
    car.setName(carName);
}

这是最好的方法吗?还是有更推荐的方法?

Is this the best way to do this or is there a more recommended way?

推荐答案

您可以按以下方式使用Optional.

You can use Optional as following.

Car car = optional.map(id -> getCar(id))
            .orElseGet(() -> {
                Car c = new Car();
                c.setName(carName);
                return c;
            });

使用if-else语句进行写操作是命令式的，它要求在if-else块之前声明变量car.

Writing with if-else statement is imperative style and it requires the variable car to be declared before if-else block.

在Optional中使用map是更实用的样式.而且这种方法不需要预先声明变量，是使用Optional的推荐方法.

Using map in Optional is more functional style. And this approach doesn't need variable declaration beforehand and is recommended way of using Optional.

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