Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
380 views
in Technique[技术] by (71.8m points)

java - Cannot instantiate generic data type in class

I have an immutable class , with the following layout ,

public final class A <T> {
    private ArrayList<T> myList;
    private A(){
        myList = new ArrayList<T>();
    }
    public A<T> addData(T t){
        A newOb = // make a new list and instantiate using overloaded constructor
        T newT = new T(); ***********ERROR HERE*************
        newOb.myList.add(newT);
        return newOb;
    }
    .........
}

The error that I get here is cannot instantiate type T . Now , I think this is related to maybe type erasure in Java.

How can I overcome this ? I want to add a new copy of the argument that is being passed to addData into my list.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)
T newT = (T) t.getClass().newInstance() // assuming zero args constructor and you'll
                                        // have to catch some reflection exceptions

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...