无法理解FluentWait中的until()方法的实现 [英] Can not understand the implementation of until() method in FluentWait

问题描述

对于Predicate<T>和Function<? super T, V>接口作为参数，org.openqa.selenium.support.ui.FluentWait中的until()方法已重载.

The until() method in org.openqa.selenium.support.ui.FluentWait is overloaded for Predicate<T> and Function<? super T, V> interfaces as parameters.

它应该采用以下(实现apply()方法的)之一作为参数:

It should take as argument one of the following (which implement the apply() method):

• 匿名类
• Lambda表达式
• 方法参考

我为此方法定义为参数的任何lambda都会引发以下错误:

Any lambda that I define as argument for this method throws following error:

WebDriverWait类型的直到(Predicate)方法不明确

The method until(Predicate) is ambiguous for the type WebDriverWait

我的Lambda:

x -> x.findElement(byLocator).isDisplayed()

我认为对于任何lambda都是如此，因为对于Function或Predicate的apply()都可以通过使用这些lambda来实现.

I assume this will be the case for any lambda, as apply() for either Function or Predicate can be implemented by use of these lambda.

所以我的问题是，以谓词为参数的直到方法的用途是什么?

已更新: 删除了由@drkthng回答的问题的第一部分.

Updated: Removed the first part of question which was answered by @drkthng.

推荐答案

回答第一个问题:

看看我引用:

public interface ExpectedCondition<T>
extends com.google.common.base.Function<WebDriver,T>

您会看到，ExpectedCondition是从Google的Function接口继承的，因此您可以将其用作till()方法的参数.

You see, that ExpectedCondition inherited from google's Function interface, thus you can use it as an argument for the until() method.

关于第二个问题:

我认为您不能像那样交出lambda.直到方法正在等待谓词或函数(如您正确提到的那样)为止.

I don't think you can hand over a lambda just like that. Until method is waiting for a Predicate or Function (as you correctly mentioned).

关于谓词和lambda之间的差异，请查看例如

Regarding the differences between Predicates and lambdas, have a look for example here

因此，您仍然可以使用lambda-expressions尝试使用类似方法:

So you can try something like this instead, still using your lambda-expressions:

Predicate<WebDriver> myPredicate = x ->x.findElement(By.id("id")).isDisplayed();

WebDriverWait wait = (WebDriverWait)new WebDriverWait(driver, 10);
wait.until(myPredicate);

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