ArrayList First Element finding

Question

I am new to Collection Framework.i am running a java program using ArrayList(). When I am trying loop it to get the elements of it, but it is throwing error like

HelloWorld.java:15: error: cannot find symbol                                                                                                                                   
           for(int k=0;k<al.length;k++)                                                                                                                                         
                           ^                                                                                                                                                    
  symbol:   variable length                                                                                                                                                     
  location: variable al of type ArrayList<String>                                                                                                                               
HelloWorld.java:17: error: array required, but ArrayList<String> found                                                                                                          
             System.out.println("elements are"+al[k]);

here is the code i written.

import java.util.ArrayList;

public class HelloWorld{
   public static void main(String[] args) {
       ArrayList<String> al = new ArrayList<String>();
       al.add("pen");
       al.add("pencil");
       al.add("ink");
       al.add("notebook");
       al.add("book");
       al.add("books");
       al.add("paper");
       al.add("white board");

       for(int k=0;k<al.length;k++)
   {
         System.out.println("elements are"+al[k]);
  }
   }
}

help me to point out my error. thanks in advance

there is no length field in ArrayList, instead you need to do method call al.size() — Volodymyr Demenkov, Jul 21 '17 at 06:15

Moishe Lipsker · Answer 1 · 2017-07-21T06:39:45.300

5

The ArrayList has a method size that returns the size of the list, and a get method to get the element stored at a particular index.

So your for loop could look like:

for(int k=0; k < al.size(); k++) {
    System.out.println("elements are" + al.get(k));
}

Or if you want you could loop through each element without an index:

for(String text : al) {
    System.out.println("elements are" + text);
}

If you want to use streams with java8, you could also do:

al.stream().forEach(System.out::println);

If you are interested, there's another answer that also talks about looping through lists in java.

edited Jul 21 '17 at 06:39

answered Jul 21 '17 at 06:15

Moishe Lipsker

2,974
2
21
29

1

Does it really work ? Indexing like `al[k]` on ArrayList should give some error ? – Sagar Gautam Jul 21 '17 at 06:23
@SagarGautam Yes you are right. I edited the answer to use the `get` method. Thanks. – Moishe Lipsker Jul 21 '17 at 06:24
1

Or `System.out::println` – shmosel Jul 21 '17 at 06:25
That's great Bro – Sagar Gautam Jul 21 '17 at 06:25

score 3 · Answer 2 · edited Jul 21 '17 at 08:23

3

Since ArrayList is a collection not an array, you may use al.size() instead.

If you want to use index try this

al.get(k)

edited Jul 21 '17 at 08:23

Purushoth

2,673
3
22
36

answered Jul 21 '17 at 06:18

kevin

31
4

score 0 · Answer 3 · answered Jul 21 '17 at 06:14

0

Try this one You can't treat arrylist as array

for(int k=0;k<al.size();k++){
    System.out.println("elements are"+ al.get(k));
}

answered Jul 21 '17 at 06:14

Sagar Gautam

9,049
6
53
84

score 0 · Answer 4 · answered Jul 21 '17 at 06:20

You can try this way :

import java.util.ArrayList;

public class HelloWorld{
   public static void main(String[] args) {
       ArrayList<String> al = new ArrayList<String>();
       al.add("pen");
       al.add("pencil");
       al.add("ink");
       al.add("notebook");
       al.add("book");
       al.add("books");
       al.add("paper");
       al.add("white board");

       for(int k=0;k<al.size();k++)
       {
         System.out.println("elements are"+ al.get(k) );
       }
   }
}

score 0 · Answer 5 · edited Jul 21 '17 at 06:23

ArrayList<String> al = new ArrayList<String>();
al.add("pen");
al.add("pencil");
al.add("ink");
al.add("notebook");
al.add("book");
al.add("books");
al.add("paper");
al.add("white board");

for(int k=0;k<al.size();k++)
  {
      System.out.println("elements are"+al.get(k));
  }

You need to use size() in order to find out the length of arraylist When you use Eclipse like Editors, hope you will overcome all these methods easily and also syntax errors itself help to learn properly.

score 0 · Answer 6 · answered Jul 21 '17 at 06:26

Since you are new to Collection You confusing Array with Arraylist . Arraylist doesnot have length . It have size() method .

Since already good option given So go with java 8 Stream

ArrayList<String> al = new ArrayList<String>();
        al.add("pen");
        al.add("pencil");
        al.add("ink");
        al.add("notebook");
        al.add("book");
        al.add("books");
        al.add("paper");
        al.add("white board");

        al.stream().forEach(System.out::println);

score -1 · Answer 7 · answered Jul 21 '17 at 06:24

import java.util.ArrayList;
public class HelloWorld
{
  public static void main(String[] args)
   {
     ArrayList<String> al = new ArrayList<String>();
     al.add("pen");
     al.add("pencil");
     al.add("ink");
     al.add("notebook");
     al.add("book");
     al.add("books");
     al.add("paper");
     al.add("white board");

     for(int k=0;k<al.size();k++)
      {
       System.out.println("elements are"+al.get(k));
      }
   }
}

ArrayList First Element finding

7 Answers7