Skipping a particular value of ArrayList during printing

Question

My Code is as follows:

ArrayList<Integer> al = new ArrayList();
al.add(1);
al.add(2);
al.add(3);
al.add(3);
al.add(4);

I want the following pattern during printing:

[1,2,4]

I tried both for loop and Iterator but I am not getting the desired output.

Help me to sort out!

I found the solution and that is

for(int i=0;i<al.size();i++) {
if(al.get(i)!=3) 
   System.out.println(al.get(i));
  }

thanks for your help

Now I want to get the same output, not through printing but by deleting elements of ArrayList, I tried with the same condition but I got exception

and the answer is

Iterator<Integer> iter = al.iterator();
        while (iter.hasNext()) {
            if (iter.next().intValue() == 3) {
                iter.remove();
            }
        }
        System.out.println(al);

This seems simple enough but what issue are you having? What output are you getting and what's wrong with it? — PakkuDon, Jan 06 '14 at 08:45
post the code you have tried please so we can see what you are doing wrong — Ross Drew, Jan 06 '14 at 08:46
You want to skip duplicates? you should describe the relationship between values in List and out put. — Ruchira Gayan Ranaweera, Jan 06 '14 at 08:48
See... If you dont tell us exactly what you want, you will get all sort of answers based on every individual's understanding... — TheLostMind, Jan 06 '14 at 08:50

score 4 · Accepted Answer · edited May 23 '17 at 12:03

4

Step through all the items in the ArrayList and test if they are equal to 3, if they are not, print them.

for (Integer i : al)  //for each Integer in the al list
{
  if (!i.equals(3))  //if it is NOT (!) equal to 3
  {
    System.out.println(i);  //then print it
  }
}

Obviously if you want to skip more than just the number 3 you will need to expand the condition the if uses.

Note on removing elements from the list

If you try and remove from the list within the loop using this method you will encounter problems with ConcurrentAccessException, this is dealt with in this question.

edited May 23 '17 at 12:03

Community

1
1

answered Jan 06 '14 at 08:48

Ross Drew

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Now I want to get the same output, not through printing but by deleting elements of ArrayList, I tried with the same condition but I got exception – Sudip7 Feb 27 '14 at 13:59
You need to provide more info but most likely a `ConcurrentAccessException` if you are trying to delete items in a for each loop. This means using the normal `for` loop i.e. `for (x;y;z)` or http://stackoverflow.com/questions/18547584/java-concurrentmodificationexception-foreachenhanced-loop-single-thread – Ross Drew Feb 27 '14 at 14:35
Good, I've expanded my answer as well. – Ross Drew Feb 28 '14 at 14:59

score 0 · Answer 2 · answered Jan 06 '14 at 08:49

0

If you want to get the list element and as per your output it seems you want to print 1 and even numbers in the list

for(int i=0; i< a1.size(); i++)  //iterate over List
{
    if(a1.get(i)%2=0 || a1.get(i) == 1) //print if 1 or even
      System.out.println(a1.get(i));
}

answered Jan 06 '14 at 08:49

eatSleepCode

4,427
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1

the number 1 is even? – TheLostMind Jan 06 '14 at 08:50
" it seems you want to print even number in the list" .. Quite frankly, he isn't telling what exactly he wants... Not your mistake.. :) – TheLostMind Jan 06 '14 at 08:51
"it seems you want to print even number in the list" this would be incorrect if OP wants to print `1` no? – Ross Drew Jan 06 '14 at 08:52
I didn't mention it in the first statement but it is there in the code and comment – eatSleepCode Jan 06 '14 at 08:53
you are assuming too much.. The OP needs to specify the logic for not printing elements.. – TheLostMind Jan 06 '14 at 08:55
This is not wrong... And I dont know if its right.. There must be logic behind this... and you are assuming it to be 1 or even number... – TheLostMind Jan 06 '14 at 09:01
All the answers for this post are assumption based, you might be thinking same for all the answers. @TheLostMind – eatSleepCode Jan 06 '14 at 12:02
Hi all, I want slight modification in my program, this time I want to delete a particular value in the ArrayList, is it possible to alter the same arrylist or I have to create a new one??? – Sudip7 Jan 27 '14 at 12:46

score 0 · Answer 3 · answered Jan 06 '14 at 08:55

0

You can also use the forEach method (Java 8):

al.forEach(v -> {if(v!=3) System.out.println(v);});

answered Jan 06 '14 at 08:55

Alexis C.

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score 0 · Answer 4 · answered Jan 06 '14 at 10:21

add the required skipping values in a list and check against that list before printing

My code:run and give comment(views please)

import java.util.*;
public class Mycode{

 public static void main(String []args){
     ArrayList<Integer> al = new ArrayList();
al.add(1);
al.add(2);
al.add(3);
al.add(3);
al.add(4);

      ArrayList<Integer> al1 = new ArrayList();
      al1.add(3);
      al1.add(2);
      int flag=0;
      for(int j=0; j< al.size(); j++)
      {
          flag=0;
      for(int i=0; i< al1.size(); i++)
      {
      if(al.get(j)==al1.get(i))
      flag=1;
      }
        if(flag==0)
      System.out.println(al.get(j));
      }
 }
}

Skipping a particular value of ArrayList during printing

4 Answers4