Java：在Eclipse和javac中处理异常的泛型 [英] Java: Generics handled differenlty in Eclipse and javac

问题描述

说我们有类

  public class Entry< K，V> {
 public Entry（K k，V v）{
 mKey = k; 
 mValue = v; 
} 
 
 public K getKey（）{
 return mKey; 
} 
 
 public V getValue（）{
 return mValue; 
} 
 
 ... 
 
} 
  

然后我们写一个扩展类，如：

  public class ExtendedEntry< K extends SomeSpecificKey，V>条目< K，V> 
  

然后，层次结构中还有一个类：

public class ConcreteEntry< Option extends Something，K extends MoreSpecificKey< Option>，V>扩展ExtendedEntry< K，V>

MoreSpecificKey here：

  public interface MoreSpecificKey< OptionType extends Something>扩展SomeSpecificKey {
 public void doSomething（OptionType option）; 
} 
  

我使用 doSomething（）方法在 ConcreteEntry 的代码中。

然后，Eclipse编译器说OK并构建代码并显示no警告。

但是 javac 回复：

... ConcreteEntry.java:6类型... ExtendedEntry和... ExtendedEntry不兼容：都定义getKey（）方法，但不相关的返回类型

当我更改（删除通用类型） MoreSpecificKey 到：

  public interface MoreSpecificKey extends SomeSpecificKey {
 public< OptionType extends Something> void doSomething（OptionType选项）; 
} 
  

ConcreteEntry ：

  public class ConcreteEntry< Option extends Something，K extends MoreSpecificKey，V>扩展ExtendedEntry< K，V> 
  

javac 中的错误已经消失，编译好也可以。

那么，Eclipse如何编译这样的代码是什么 - 它是编译器参数定义的还是不同的首选项，或编译器的差异。如何在Eclipse中处理（修复）这一点，并确保它将在 javac 中编译。

解决方案

部分内容已在问题 Eclipse中找到javac来编译项目的位置？ a> - Eclipse使用不同的编译器

Say we have class

public class Entry<K, V> {
  public Entry(K k,V v) { 
    mKey = k;
    mValue = v;   
  }

  public K getKey() {
    return mKey;
  }

  public V getValue() {
    return mValue;
  }

  ...

}

Then we write an extending class like:

public class ExtendedEntry<K extends SomeSpecificKey, V> extends Entry<K, V>

Then, one class more in the hierarchy:

public class ConcreteEntry<Option extends Something, K extends MoreSpecificKey<Option>, V> extends ExtendedEntry<K, V>

MoreSpecificKey here:

public interface MoreSpecificKey<OptionType extends Something> extends SomeSpecificKey {
    public void doSomething(OptionType option);
}

And I use doSomething() method somewhere in the code of ConcreteEntry.

Then Eclipse compiler says OK and builds code and shows no warnings.

But javac responses:

...ConcreteEntry.java:6 types ...ExtendedEntry and ...ExtendedEntry are incompatible: both define getKey() method, but unrelated return types

When I change (removing generic type) MoreSpecificKey to:

public interface MoreSpecificKey extends SomeSpecificKey {
    public <OptionType extends Something> void doSomething(OptionType option);
}

ConcreteEntry definition now:

public class ConcreteEntry<Option extends Something, K extends MoreSpecificKey, V> extends ExtendedEntry<K, V>

Error in javac is gone, and everything is compiled OK too.

So, what's the reason Eclipse compiles code like this -- is it any compiler parameter defined or different preferences, or differences in compilers. How to handle (fix) this while developing in Eclipse and be sure that it will compile in javac.

解决方案

part of this is already explained in the Question Where does Eclipse find javac to compile a project? - Eclipse uses a different compiler

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