Java中的泛型，合并方法 [英] Generics in Java, Merge method

问题描述

我必须创建一个合并方法来合并两个列表（基于数组的列表）。我的方法可行，但现在我必须将我的方法改为泛型。这是我的方法没有泛型，它的工作原理。但我有麻烦转换为泛型。

I have to create a Merge method to merge together two lists (Array-Based Lists). My method works, but now I have to change my method to generics. This is my method without generics, and it works. But I have having troubling converting it to generics.

public OrderedArrayList merge(OrderedArrayList list2){
        OrderedArrayList result = new OrderedArrayList(length + list2.length);
        int list1Index = 0;
        int list2Index = 0;
        for (int i = 0; i < result.maxSize; i++) {
            if (list1Index == list.length) {
                result.insert(list2.list[list2Index]);
                list2Index++;
            } else if (list2Index == list2.length) {
                result.insert(list[list1Index]);
                list1Index++;
            } else if (list[list1Index] < list2.list[list2Index]) {
                result.insert(list[list1Index]);
                list1Index++;
            } else {
                result.insert(list2.list[list2Index]);
                list2Index++;
            }
        }
        return result;
    }

这是我尝试将上述消息转换为泛型。

This is my attempt at converted the above message to generics.

public  <T extends Comparable<T> > OrderedArrayList1<T> merge(OrderedArrayList1<T> list2){
        OrderedArrayList1 result = new OrderedArrayList1(length + list2.length);
        int list1Index = 0;
        int list2Index = 0;
        for (int i = 0; i < result.maxSize; i++) {
          T temp = list[list1Index];
          T temp1 = list[list2Index];
            if (temp.compareTo(temp1) == 0) {
                result.insert(list2.list[list2Index]);
                list2Index++;
            } else if (temp1.compareTo(temp)==0) {
                result.insert(list[list1Index]);
                list1Index++;
            } else if (temp.compareTo(temp1) < 0) {
                result.insert(list[list1Index]);
                list1Index++;
            } else {
                result.insert(list2.list[list2Index]);
                list2Index++;
            }
        }
        return result;
    }

有很多错误，并且不符合或不能正常工作。这是我不断收到的错误之一：
错误：不兼容的类型：T不能转换为T

There are many errors, and it is not complying or working. This is one of the errors that I keep getting: Error: incompatible types: T cannot be converted to T

谢谢。

推荐答案

假设您已声明< T extends Comparable< T> >< / code>在类级别，将其从方法中删除：



Assuming you have declared <T extends Comparable<T> > at the class level, remove it on the method:

class OrderedArrayList1<T extends Comparable<T> > {
  public OrderedArrayList1<T> merge(OrderedArrayList1<T> list2) {
    ...
  }
}

否则，你定义了一个不同的类型变量，它恰好具有相同的名称，因此稍微隐蔽的T不能转换为T消息。

Otherwise, you're defining a different type variable which just happens to have the same name, hence the slightly cryptic "T cannot be converted to T" message.

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