Java泛型在Eclipse中编译,但不在javac中 [英] Java generics compile in Eclipse, but not in javac
问题描述
我不得不发现我在我的项目中有Java代码,它在Eclipse中编译和运行良好,但在javac中引发了编译错误。
I had to discover I have Java code in my project, which compiles and runs fine in Eclipse, but throws a compilation error in javac.
一个自包含snippet:
A self-contained snippet:
import java.util.HashSet;
import java.util.Set;
public class Main {
public static void main(String[] args) {
Set<Integer> setOfInts = new HashSet<Integer>();
Set<Object> setOfObjects = covariantSet(setOfInts);
}
public static <S, T extends S> Set<S> covariantSet(Set<T> set) {
return new HashSet<S>(set);
}
}
javac中的编译返回: p>
Compilation in javac returns:
Main.java:10: incompatible types
found : java.util.Set<java.lang.Integer>
required: java.util.Set<java.lang.Object>
Set<Object> setOfObjects = covariantSet(setOfInts);
^
此错误现在阻止在Maven中构建项目。因为Eclipse编译器被建造为更容忍,我现在必须假设如上所述的代码段的定义和用法静态方法是无效的Java?
This error now prevents building the project in Maven. As the Eclipse compiler is built to be more tolerant, I now have to assume the definition and usage of snippets as above static method is no valid Java?
推荐答案
看来Sun的1.6 JDK无法推断出正确的类型。以下似乎在我的机器上工作:
It seems that Sun's 1.6 JDK can't infer the correct type. The following seems to work on my machine:
Set<Object> setOfObjects = Main.<Object, Integer>covariantSet(setOfInts);
请注意,您必须调用静态方法前缀为类名
Note that you must invoke the static method prefixed with the class name
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