Question

我正在尝试将一个字符串数组添加到arrayList中。以下是代码：

import java.util.ArrayList;
import java.util.List;
import java.util.Collections;
import java.util.Arrays;

class AddAll{
    public static void main(String[] args){
        String[] words = {"apples","beef","corn","ham"};
        List<String> list = Arrays.asList(words);

        ArrayList<String> arrayList = new ArrayList<String>();
        arrayList.add("Youtube");
        arrayList.add("Google");
        arrayList.add("Facebook");

        for(String x : arrayList){
        System.out.printf("%s ",x);
        }
        System.out.println();

        Collections.addAll(arrayList,list);

      for(String x : arrayList){
        System.out.printf("%s ",x);
    }
  }
 }

但是，在编译期间，它会抛出错误。我无法弄清楚如何解决它？有人可以帮我这个代码吗？

  AddAll.java:21: error: method addAll in class Collections cannot be applied to           given types;
    Collections.addAll(arrayList,list);
               ^
  required: Collection<? super T>,T[]
   found: ArrayList<String>,List<String>
  reason: inferred type does not conform to upper bound(s)
  inferred: List<String>
   upper bound(s): String,Object
   where T is a type-variable:
    T extends Object declared in method <T>addAll(Collection<? super T>,T...)

1错误

Answer 1

Collections类中没有接受List或Collection类型的两个参数的方法。

有List#add(Collection)可以执行您提出的问题

arrayList.addAll(list);

如何使用集合添加列表（字符串数组）和arrayList？

1 个答案: