无法在类中实例化通用数据类型 [英] Cannot instantiate generic data type in class

问题描述

我有一个不可变的类，具有以下布局：

  public final class A< T> {
 private ArrayList< T>我的列表; 
 private A（）{
 myList = new ArrayList< T>（）; 
} 
 public A< T> addData（T t）{
 newOb = //创建一个新列表并使用重载的构造函数实例化
 T newT = new T（）; ***********错误************* 
 newOb.myList.add（newT）; 
返回newOb; 
} 
 ......... 
} 
  

我在这里得到的错误是不能实例化类型T 。现在，我认为这与Java中的 type erasure 有关。

我该如何克服这个问题？我想将传递给addData的参数的新副本添加到我的列表中。

解决方案

在java语言中，泛型是通过擦除来实现的，所以不可能实例化泛型。也不可能灌输一个泛型类型的数组等。

我该如何克服这个问题？我想将传递给addData的参数
的新副本添加到列表中。使用 Cloneable 接口作为绑定的类型或添加您自己的类似接口。

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.

解决方案

In java language generics are implemented by erasure, so it is impossible to instantiate a generic type. Also it is impossible to instiate an array of generic type and so on.

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

You can try to use Cloneable interface as a type bound or add your own similar interface.

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