both methods have same erasure, yet neither overrides the other 【泛型型別擦除與過載和覆蓋問題】
public class Father {
void test(Object o){}
}
class Son<T> extends Father{
void test(T o){}//編譯錯誤!
}
這段程式碼會報一個編譯錯誤,both methods have same erasure, yet neither overrides the other。
這個錯誤的意思是,兩個方法在型別擦除後,具有相同的原生型別引數列表,但是也不能覆蓋另一個方法。
泛型型別在編譯後,會做型別擦除,只剩下原生型別。如引數列表中的T型別會編譯成Object,但是會有一個Signature。
儘管兩個test方法具有相同的位元組碼,但是型別引數資訊用 一個新的簽名(signature) 屬性記錄在類模式中。JVM 在裝載類時記錄這個簽名信息,並在執行時通過反射使它可用。
這就導致了這個方法既不能作為覆蓋父類test方法的方法,也不能作為test方法的過載。
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