Java 8 方法引用：提供能够提供参数化结果的供应商
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Java 8 method references: provide a Supplier capable of supplying a parameterized result
提问by mdo
I'd like to use
我想用
java.util.Optional.orElseThrow()
with an Exception type that asks for a constructor parameter. Something like this:
具有要求构造函数参数的异常类型。像这样的东西：
orElseThrow(MyException::new(someArgument)) // obviously NOT working
Is there a way to create a Supplier that passes my argument value in?
有没有办法创建一个供应商来传递我的参数值？
采纳答案by Louis Wasserman
Sure. orElseThrow(() -> new MyException(someArgument)).
当然。 orElseThrow(() -> new MyException(someArgument)).
回答by Manu
It appears that you can throw only RuntimeException from the method orElseThrow. Otherwise you will get an error message like MyException cannot be converted to java.lang.RuntimeException
看来您只能从方法中抛出 RuntimeException orElseThrow。否则你会收到类似的错误信息 MyException cannot be converted to java.lang.RuntimeException
Update:- This was an issue with an older version of JDK. I don't see this issue with the latest versions.
更新：- 这是旧版本 JDK 的问题。我在最新版本中没有看到这个问题。
回答by Ashish Pushp
optionalUsers.orElseThrow(() -> new UsernameNotFoundException("Username not found"));
