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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