JAVA String concatenanting with comma

Question

Hey guys can somebody show me a way good way of concatenating these strings with commas

Basically Im building a header criteria string showing which forms variables have been selected. I need to put commas in between the values and keep the break tags in place...can somebody see a better way to do it. I didnt want commas if there were just on value

This is what it looks like currently formatted:

enter image description here

protected final String getCriteriaHeader(MetricFilterCriteriaForm form)
{
    String filterCriteria = "<br/>";

    }
    if (form.isSacNone() || form.isSac1() || form.isSac2() || form.isSac3())
    {
        filterCriteria = filterCriteria + "SAC:";
    }
    if (form.isSacNone())
    {
        filterCriteria = filterCriteria + " NONE";
    }
    if (form.isSac1())
    {
        filterCriteria = filterCriteria + " 1";
    }
    if (form.isSac2())
    {
        filterCriteria = filterCriteria + " 2";
    }
    if (form.isSac3())
    {
        filterCriteria = filterCriteria + " 3";
    }
    if (form.isSac1() || form.isSac2() || form.isSac3())
    {
        filterCriteria = filterCriteria + "<br/>";
    }
    if (form.isRegularScheduleType() || form.isLotScheduleType() || form.isBatchScheduleType())
    {
        filterCriteria = filterCriteria + "Schedule Type:";
    }
    if (form.isRegularScheduleType())
    {
        filterCriteria = filterCriteria + " Regular";
    }
    if (form.isLotScheduleType())
    {
        filterCriteria = filterCriteria + " Lot";
    }
    if (form.isBatchScheduleType())
    {
        filterCriteria = filterCriteria + " Batch";
    }

    return filterCriteria;
}

What have you tried? What conditions define 'good'? I'm guessing 'has a red stripe' simply because that is very spiffy. — Andrew Thompson
– Andrew Thompson, Commented Feb 20, 2013 at 14:51

Cyrille Ka · Accepted Answer · 2013-02-20 14:55:24Z

3

There are different ways to concatenate a set of values in a string with a separator.

With StringBuilder

Add the values with the comma, then remove the last comma manually.

StringBuilder sb = new StringBuilder();
if (/*condition1*/) {
    sb.add("A,"); // value with comma
}
if (/*condition2*/) {
    sb.add("B,");
}
sb.delete(sb.length()-1, sb.length()); // remove last character, which is the comma.
String result = sb.toString(); // get the result string.

With Guava's Joiner

Put it all in a List and use Joiner.

List<String> list = Lists.newArrayList();
if (/*condition1*/) {
    list.add("A"); // no comma here
}
if (/*condition2*/) {
    list.add("B");
}
String result = Joiner.on(",").join(list); // use Joiner to join elements of the list.

Alternatively to Guava, there is StringUtils.Join from Apache Common Lang. See @Iswanto San's answer.

answered Feb 20, 2013 at 14:55

Cyrille Ka

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1 Comment

Quetzalcoatl Over a year ago

Nice alternative with the Joiner, got to love Guava.

Iswanto San · Accepted Answer · 2013-02-20 14:55:38Z

You can use StringUtils.Join from Apache Common Lang

Example :

protected final String getCriteriaHeader(MetricFilterCriteriaForm form)
{
    String filterCriteria = "<br/>";
    List<String> sacs = new ArrayList<String>();
    List<String> schedules = new ArrayList<String>();

    if (form.isSacNone() || form.isSac1() || form.isSac2() || form.isSac3())
    {
        filterCriteria = filterCriteria + "SAC:";
    }
    if (form.isSacNone())
    {
        filterCriteria = filterCriteria + " NONE";
    }
    if (form.isSac1())
    {
        sacs.add(" 1");
    }
    if (form.isSac2())
    {
        sacs.add(" 2");
    }
    if (form.isSac3())
    {
        sacs.add(" 3");
    }
    filterCriteria += StringUtils.join(saces, ",");
    if (form.isSac1() || form.isSac2() || form.isSac3())
    {
        filterCriteria = filterCriteria + "<br/>";
    }
    if (form.isRegularScheduleType() || form.isLotScheduleType() || form.isBatchScheduleType())
    {
        filterCriteria = filterCriteria + "Schedule Type:";
    }
    if (form.isRegularScheduleType())
    {
        schedules.add(" Regular");
    }
    if (form.isLotScheduleType())
    {
        schedules.add(" Lot");
    }
    if (form.isBatchScheduleType())
    {
        schedules.add(" Batch");
    }
    filterCriteria+=StringUtils.join(schedules, ",");

    return filterCriteria;
}

MrSmith42 · Accepted Answer · 2013-02-20 15:16:35Z

At first avoid creating so much String instances by using StringBuilder. Then nest the conditions to speed things up a bit and to get more structure.

protected final String getCriteriaHeader(MetricFilterCriteriaForm form)
{
    StringBuilder filterCriteria = new StringBuilder("<br/>");
    if (form.isSacNone() || form.isSac1() || form.isSac2() || form.isSac3())
    {
        filterCriteria.append("SAC:");
        if (form.isSacNone())
            filterCriteria.append(" NONE");
        if (form.isSac1() || form.isSac2() || form.isSac3())
        {
            if (form.isSac1())
                filterCriteria.append(" 1,");
            if (form.isSac2())
                filterCriteria.append(" 2,");
            if (form.isSac3())
                filterCriteria.append(" 3,");
            if(','==filterCriteria.charAt(filterCriteria.length-1) )
                filterCriteria.deleteCharAt(filterCriteria.length-1)
            filterCriteria.append("<br/>");
        }
    }
    if (form.isRegularScheduleType() || form.isLotScheduleType() || form.isBatchScheduleType())
    {
        filterCriteria.append("Schedule Type:");
        if (form.isRegularScheduleType())
            filterCriteria.append(" Regular,");
        if (form.isLotScheduleType())
            filterCriteria.append(" Lot,");
        if (form.isBatchScheduleType())
            filterCriteria.append(" Batch,");
        if(','==filterCriteria.charAt(filterCriteria.length-1) )
            filterCriteria.deleteCharAt(filterCriteria.length-1)
    }
    return filterCriteria.toString();
}

If only one condition can be true,you can also use else if instead of cascades of if.

Thanks...but you didnt append any commas anywhere....you just rewrote it with stringBuilder

user1706698 · Accepted Answer · 2013-02-20 14:51:49Z

1

You could use a StringBuilder to build the string, it's better than simple string concatenation :

StringBuilder sb = new StringBuilder();
if(XX) {
  sb.append("XX");
}
return sb.toString();

Hope this helps :)

PS: Note that StringBuilder is faster than StringBuffer, but the latter is Thread-safe.

EDIT

I re-read your question, and it seems I don't answer it well, although I provided useful advice (IMHO). I don't understand exactly what you need.

answered Feb 20, 2013 at 14:51

user1706698

1 Comment

Ishikawa Yoshi Over a year ago

i want to publish the same but you faster ;) +1

Boris the Spider · Accepted Answer · 2013-02-20 14:57:10Z

I would suggest whacking the thing into a List then using a StringBuilder:

protected final String getCriteriaHeader(MetricFilterCriteriaForm form) {
        final StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append("<br/>");

        final List<String> sacList = new LinkedList<String>();
        if (form.isSacNone() || form.isSac1() || form.isSac2() || form.isSac3()) {
            stringBuilder.append("SAC: ");
        }
        if (form.isSacNone()) {
            sacList.add("NONE");
        }
        if (form.isSac1()) {
            sacList.add("1");
        }
        if (form.isSac2()) {
            sacList.add("2");
        }
        if (form.isSac3()) {
            sacList.add("3");
        }
        final Iterator<String> sacIter = sacList.iterator();
        while (sacIter.hasNext()) {
            stringBuilder.append(sacIter.next());
            if (sacIter.hasNext()) {
                stringBuilder.append(", ");
            }
        }
        if (form.isSac1() || form.isSac2() || form.isSac3()) {
            stringBuilder.append("<br/>");
        }
        final List<String> scheduleTypeList = new LinkedList<String>();
        if (form.isRegularScheduleType() || form.isLotScheduleType() || form.isBatchScheduleType()) {
            scheduleTypeList.add("Schedule Type: ");
        }
        if (form.isRegularScheduleType()) {
            scheduleTypeList.add("Regular");
        }
        if (form.isLotScheduleType()) {
            scheduleTypeList.add("Lot");
        }
        if (form.isBatchScheduleType()) {
            scheduleTypeList.add("Batch");
        }
        final Iterator<String> scheduleTypeIter = scheduleTypeList.iterator();
        while (scheduleTypeIter.hasNext()) {
            stringBuilder.append(scheduleTypeIter.next());
            if (scheduleTypeIter.hasNext()) {
                stringBuilder.append(", ");
            }
        }
        return stringBuilder.toString();
}

Hey thanks for the quick response......I prolly will change it over to use stringBuilder later on

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JAVA String concatenanting with comma

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