How to add list( array of strings) and arrayList using collections?

Question

I am trying to add an array of strings to an arrayList . Below is the code:

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);
    }
  }
 }

However, during compilation it throws below error. I am not able to figure out how to resolve it? Can someone help me with this code?

  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 error

Where did you see/find a method like Collections.addAll(arrayList,list);? — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Apr 4, 2015 at 0:04
Advice: if you get a compilation error that tells you that a method cannot be found or applied ... read the javadocs ... to find out if the method actually exists, and to check you are calling it with the correct number and types of arguments. — Stephen C
– Stephen C, Commented Apr 4, 2015 at 1:37
Hi Stephen, Thank you for the advice. I am just in a learning process. As per your advice I went through javadocs and I could see that method exists. Now the question is how to use it? :( — Brenda Olivia Martis
– Brenda Olivia Martis, Commented Apr 4, 2015 at 15:42

Sotirios Delimanolis · Accepted Answer · 2015-04-04 00:05:32Z

1

There is no method in the Collections class which accepts two arguments of type List or Collection.

There is List#add(Collection) which can do what you're asking about

arrayList.addAll(list);

answered Apr 4, 2015 at 0:05

Sotirios Delimanolis

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1 Comment

Brenda Olivia Martis Over a year ago

Thank you Sotirios. Looks like I was going through some old references.

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