Java - Append quotes to strings in an array and join strings in an array

Question

I would like to append double quotes to strings in an array and then later join them as a single string (retaining the quotes). Is there any String library which does this?

Answer 1

String output = "\"" + StringUtils.join(listOfStrings , "\",\"") + "\"";

Answer 2

You can create the code for this functionality yourself as well:

String output = "";

for (int i = 0; i < listOfStrings.length; i++)
{
    listOfStrings[i] = "\"" + listOfStrings[i] + "\"";
    output += listOfStrings[i] + ", ";
}

Answer 3

public static void main(String[] args) {
    // TODO code application logic here
    String [] listOfStrings = {"day", "campaign", "imps", "conversions"};
    String output = "";

    for (int i = 0; i < listOfStrings.length; i++) {
        output += "\"" + listOfStrings[i] + "\"";
        if (i != listOfStrings.length - 1) {
            output += ", ";
        }
    }

    System.out.println(output);
}

Output: "day", "campaign", "imps", "conversions"

Answer 4

With Java 8+

Java 8 has Collectors.joining() and its overloads. It also has String.join.

Using a Stream and a Collector

With a reusable function

Function<String,String> addQuotes = s -> "\"" + s + "\"";

String result = listOfStrings.stream()
  .map(addQuotes)
  .collect(Collectors.joining(", "));

Without any reusable function

String result = listOfStrings.stream()
  .map(s -> "\"" + s + "\"")
  .collect(Collectors.joining(", "));

Shortest (somewhat hackish, though)

String result = listOfStrings.stream()
  .collect(Collectors.joining("\", \"", "\"", "\""));

Using String.join

Very hackish. Don't use except in a method called wrapWithQuotesAndJoin.

String result = listOfString.isEmpty() ? "" : "\"" + String.join("\", \"", listOfStrings) + "\"";

With older versions of Java

Do yourself a favor and use a library. Guava comes immediately to mind.

Using Guava

Function<String,String> addQuotes = new Function<String,String>() {
  @Override public String apply(String s) {
    return new StringBuilder(s.length()+2).append('"').append(s).append('"').toString();
  }
};
String result = Joiner.on(", ").join(Iterables.transform(listOfStrings, addQuotes));

No libraries

String result;
if (listOfStrings.isEmpty()) {
  result = "";
} else {
  StringBuilder sb = new StringBuilder();
  Iterator<String> it = listOfStrings.iterator();
  sb.append('"').append(it.next()).append('"'); // Not empty
  while (it.hasNext()) {
    sb.append(", \"").append(it.next()).append('"');
  }
  result = sb.toString();
}

Note: all the solutions assume that listOfStrings is a List<String> rather than a String[]. You can convert a String[] into a List<String> using Arrays.asList(arrayOfStrings). You can get a Stream<String> directly from a String[] using Arrays.stream(arrayOfString).

Answer 5

Add the quotes along with the separator and then append the quotes to the front and back.

"\"" + Joiner.on("\",\"").join(values) + "\""

Answer 6

There is no method present in JDK which can do this, but you can use the Apache Commons Langs StringUtls class , StringUtils.join() it will work