Convert ArrayList to String

Question

I have an ArrayList and I need to convert it to one String.

Each value in the String will be inside mark and will be separated by comma something like this:

ArrayList list = [a,b,c]

String s = " ’a’,’b’,’c’ ";

I am looking for efficient solution .

I am looking for efficient solution -> First, do you know how to do it inefficiently? — Rohit Jain
– Rohit Jain, Commented Oct 21, 2012 at 20:19
possible duplicate of Best way to convert an ArrayList to a string — Kai
– Kai, Commented Oct 22, 2012 at 20:32

Rohit Jain · Accepted Answer · 2013-10-25 18:17:36Z

8

You can follow these steps: -

Create an empty StringBuilder instance

StringBuilder builder = new StringBuilder();

Iterate over your list
For each element, append the representation of each element to your StringBuilder instance
```
builder.append("'").append(eachElement).append("', ");
```
Now, since there would be a last comma left, you need to remove that. You can use StringBuilder.replace() to remove the last character.

You can take a look at documentation of StringBuilder to know more about various methods you can use.

edited Oct 25, 2013 at 18:17

answered Oct 21, 2012 at 20:26

Rohit Jain

214k45 gold badges419 silver badges534 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Zane Over a year ago

I really like your idea of getting rid of the one comma too many. I always do it with an if inside the loop, but your solution is more efficient.

Rohit Jain Over a year ago

@Zane. Well, why would you need an if for that? but that would be better to remove it forehand.

adarshr Over a year ago

What's the point of using a StringBuilder if you still end up doing append("'" + eachElement + "', ")?

billjamesdev Over a year ago

@Rohit Adarshr's complaint is that the line should be replaced with 3 appends... since you're doing String addition in the append, which is what you try to avoid by using a StringBuilder in the first place.

Rohit Jain Over a year ago

@BillJames. Ah! Man you're right. Sorry adarsh. will edit it. :)

|

Makoto · Accepted Answer · 2012-10-21 20:25:52Z

0

Take a look at StringBuilder and StringBuffer:

StringBuffer

StringBuilder

edited Oct 21, 2012 at 20:25

Makoto

107k29 gold badges199 silver badges236 bronze badges

answered Oct 21, 2012 at 20:22

Bernd Elkemann

23.6k4 gold badges40 silver badges72 bronze badges

Comments

dimitrisli · Accepted Answer · 2012-10-21 20:50:39Z

0

Maybe an overkill here but providing a more functional approach through Guava:

import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.collect.Collections2;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;


public class Main {

    public static void main(String ... args){
        List<String> list = new ArrayList(){{add("a");add("b");add("c");}};
        Collection<String> quotedList = Collections2.transform(list,new Function<String, String>() {
            @Override
            public String apply(String s) {
                return "'"+s+"'";
            }
        });
        System.out.println(Joiner.on(",").join(quotedList));
    }
}

edited Oct 21, 2012 at 20:50

answered Oct 21, 2012 at 20:29

dimitrisli

21.4k12 gold badges64 silver badges65 bronze badges

Comments

Marcin Wasiluk · Accepted Answer · 2012-10-21 20:59:34Z

0

use StringUtils library from Apache org.apache.commons.lang3.StringUtils;

    StringUtils.join(list, ", ");

or

String s = (!list.isEmpty())? "'" + StringUtils.join(list , "', '")+ "'":null;

edited Oct 21, 2012 at 20:59

answered Oct 21, 2012 at 20:48

Marcin Wasiluk

4,9044 gold badges42 silver badges46 bronze badges

Collectives™ on Stack Overflow

Convert ArrayList to String

4 Answers 4

6 Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

6 Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related