为什么下面的代码有错误？为什么重载不成功？
// signatures of the reset method at //1 and //2 after erasure will be different
// then why don't they overload?
public class Test<T>{
public static void main(String[] args) {
WordBox<String> city = new WordBox<String>("Skogland");
city.reset("waiting"); // error: ambiguous
}
}
class Box <T> {
private T theThing;
public Box( T t) { theThing = t; }
public void reset( T t) { theThing = t; } //1
}
class WordBox< S extends CharSequence > extends Box< String > {
public WordBox( S t) { super(t.toString().toLowerCase()); }
public void reset( S t) { super.reset(t.toString().toLowerCase()); } //2
}
// signatures of the reset method at //1 and //2 after erasure will be different
// then why don't they overload?
public class Test<T>{
public static void main(String[] args) {
WordBox<String> city = new WordBox<String>("Skogland");
city.reset("waiting"); // error: ambiguous
}
}
class Box <T> {
private T theThing;
public Box( T t) { theThing = t; }
public void reset( T t) { theThing = t; } //1
}
class WordBox< S extends CharSequence > extends Box< String > {
public WordBox( S t) { super(t.toString().toLowerCase()); }
public void reset( S t) { super.reset(t.toString().toLowerCase()); } //2
}
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评论（1）
java.lang.String扩展了CharSequence，因此调用city.reset("waiting")与WordBox.reset(S extends CharSequence)和Box.reset(String)。要解决此问题，您应该确保
WordBox.reset()接受与Box.reset()相同的类型，在这种情况下WordBox.reset()覆盖Box.reset()，或者相反，确保WordBox.reset()接受与Word.reset 不重叠的类型()，在这种情况下，WordBox.reset()会重载Box.reset()。在您给出的示例中，我感觉您可能希望WordBox.reset()覆盖Box.reset()。java.lang.StringextendsCharSequence, so callingcity.reset("waiting")matches bothWordBox.reset(S extends CharSequence)andBox.reset(String).To fix the problem, you should either ensure
WordBox.reset()accepts the same type asBox.reset(), in which caseWordBox.reset()overridesBox.reset(), or, conversely, make sureWordBox.reset()accepts a type that does not overlap withWord.reset(), in which caseWordBox.reset()overloadsBox.reset(). In the example you give, I get the feeling you'd probably wantWordBox.reset()to overrideBox.reset().