我怎样才能安全地上传一个可选的? [英] How can I safely upcast an Optional?

问题描述

假设我有一个 Optional< Exception> ，并想将其强制转换为 Optional< Throwable> .有没有比这更漂亮的方法了?

Suppose I have an Optional<Exception> and want to cast it to an Optional<Throwable>. Are there any prettier ways of doing this rather than:

Optional<Exception> optionalException = Optional.of(new Exception());
Optional<Throwable> optionalThrowable = (Optional<Throwable>) (Optional<? extends Throwable>) optionalException;

此解决方案会在IntelliJ中生成棉绒警告.

This solution generates a lint warning in IntelliJ.

Unchecked cast: 'java.util.Optional<capture<? extends java.lang.Throwable>>' to 'java.util.Optional<java.lang.Throwable>'

推荐答案

找到了它:

Optional<Exception> optionalException = Optional.of(new Exception());
Optional<Throwable> optionalThrowable = optionalException.map(Function.identity());

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