How to get desired format from ArrayList

Question

import java.net.UnknownHostException;
import java.text.DecimalFormat;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.List;

import org.apache.log4j.Logger;

public class Test {
    final static Logger logger = Logger.getLogger(Test.class);
    private static DecimalFormat decimal_inpoints = new DecimalFormat("0.00");

    public static void main(String args[]) throws UnknownHostException,
            ParseException {

        ArrayList<Integer> array_list = new ArrayList<Integer>();

        array_list.add(1);
        array_list.add(0);

        String joinedString = array_list.toString();

        System.out.println(joinedString);

    }

}

How can i get output as 1,0

When i used array_list.toString(); its giving putput as [1,0] (array added )

Could you please tell me How to get 1,0 instead of [1,0]

The simplest way is to perform the "joining" operation yourself... have you tried doing that? (Use a StringBuilder, appending an item then a comma, etc.) Also note that your code doesn't do anything that would generate an UnknownHostException or a ParseException, nor do you use the logger or DecimalFormat. All of that can be removed from your code, to make it simpler to see what you're interested in. — Jon Skeet
– Jon Skeet, Commented Mar 4, 2016 at 14:05
This is the default implementation of toString() of ArrayList class. Your have to write your own method to get string in desired format which you can easily do using StringBuilder. — Mahendra
– Mahendra, Commented Mar 4, 2016 at 14:06
You should check this post: http://stackoverflow.com/questions/1978933/a-quick-and-easy-way-to-join-array-elements-with-a-separator-the-opposite-of-sp — sahel
– sahel, Commented Mar 4, 2016 at 14:08

Emdadul Sawon · Accepted Answer · 2016-05-18 08:39:35Z

6

Using Apache Commons Lang:

String join = StringUtils.join(joinList, ",");

Using Java 8

String joined = String.join(",", list);

Using Google Guava (Joiner)

Joiner joiner = Joiner.on(",");
String join = joiner.join(joinList);

Using StringBuilder

StringBuilder builder = new StringBuilder(array_list.size());
boolean isFirst = true;
for (int i : array_list){
  if (isFirst) {
    builder.append(i);
    isFirst = false;
  } else {
    builder.append(", " + i);
  }
}
System.out.println(builder.toString());

edited May 18, 2016 at 8:39

answered Mar 4, 2016 at 14:34

Emdadul Sawon

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Y.Kaan Yılmaz · Accepted Answer · 2016-03-04 14:08:09Z

3

simpliest way is;

array_list.toString().replace("[","").replace("]","");

answered Mar 4, 2016 at 14:08

Y.Kaan Yılmaz

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1 Comment

Y.Kaan Yılmaz Over a year ago

string.replace() is not exist in java 7 ? I'm really surprised. EDIT: just checked out java 7 docs and I see there is string.replace() method. how is that possible you cannot use it ? docs.oracle.com/javase/7/docs/api/java/lang/String.html

Peter Zeller · Accepted Answer · 2016-03-04 14:08:51Z

3

In Java 8 you can do it with the joining Collector:

    String joinedString = list.stream()
            .map(Object::toString)
            .collect(Collectors.joining(", "));

answered Mar 4, 2016 at 14:08

Peter Zeller

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Comments

Community · Accepted Answer · 2017-05-23 12:02:56Z

1

When using Java 8. See here.

private toStringNoBrackets(ArrayList MyList) {
    return String.join(",", MyList);
}

edited May 23, 2017 at 12:02

CommunityBot

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answered Mar 4, 2016 at 14:13

Bram Vanroy

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Comments

Jason Portnoy · Accepted Answer · 2016-03-04 14:16:55Z

1

You can create your own class and override the toString method.

import java.util.ArrayList;

public class MyIntegerArrayList extends ArrayList<Integer>
{
    @Override
    public String toString(){
        return super.toString().replace("[","").replace("]","");
    }
}


MyIntegerArrayList myIntegerArrayList = new MyIntegerArrayList();
myIntegerArrayList.add(0);
myIntegerArrayList.add(1);
myIntegerArrayList.toString();

answered Mar 4, 2016 at 14:16

Jason Portnoy

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user5547025 · Accepted Answer · 2016-03-04 14:11:33Z

0

Use StringJoiner:

import java.util.ArrayList;
import java.util.List;
import java.util.StringJoiner;

public class SOPlayground {

    public static void main(String[] args) {
        List<Integer> array_list = new ArrayList<>();
        array_list.add(1);
        array_list.add(0);

        StringJoiner sj = new StringJoiner(", ");
        array_list.stream().forEach((i) -> {
            sj.add(i.toString());
        });
        System.out.println(sj.toString());
    }

}

Output:

1, 0

answered Mar 4, 2016 at 14:11

user5547025

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How to get desired format from ArrayList

6 Answers 6

Using Apache Commons Lang:

Using Java 8

Using Google Guava (Joiner)

Using StringBuilder

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Collectives™ on Stack Overflow

6 Answers 6

Using Apache Commons Lang:

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Using Google Guava (Joiner)

Using StringBuilder

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