How To Convert An Array To Comma Separated String Inwards Java

The simplest agency to convert an array to comma separated String is to practise a StringBuilder, iterate through the array, in addition to add together each chemical constituent of the array into StringBuilder subsequently appending comma. You only demand Java 1.5 for that, fifty-fifty if you lot are non running on Java 5, you lot tin utilisation StringBuffer inwards house of StringBuilder. The joining of String has got fifty-fifty easier inwards JDK 8, where you lot receive got got the join() method correct inwards the String course of didactics itself. The join() method takes a delimiter in addition to a source, which tin last array or collection in addition to returns a String where each chemical constituent is joined past times a delimiter. If you lot desire to practise a CSV string, only transcend comma equally a delimiter. Btw, these ii methods are non the exclusively agency to practise a comma separated String from an array, you lot tin equally good utilisation Apache Commons or Spring framework's utility course of didactics to practise the same.


Now the query comes, why practise you lot demand to convert an array to a comma-separated String? Well, in that place tin last many situations but I'll give you lot mine. Sometimes back, I was writing about JDBC code to shop about fields into the database. One of the fields was String array which needs to last stored inwards a VARCHAR column, in addition to I don't desire to shop the string returned past times the Arrays.toString() method.

The best selection was to shop comma separated values in addition to thus I looked into JDK API for whatsoever method which tin practise that, in that place wasn't any. So, I rapidly wrote 1 equally seen inwards the get-go example. Later, I did a picayune chip of enquiry in addition to come upwards up alongside 4 dissimilar ways to convert a String array to comma separated String inwards Java.

4 Ways to Convert String Array to Comma Separated String

Here are my 4 examples of converting a String array to CSV text. Though you lot tin utilisation the same technique in addition to code to practise CSV string from whatsoever array e.g. int array, float array or an object array, provided your object has a meaningful String representation.


1) Using Plain Java
This is the simplest agency to orbit the task. All you lot demand to practise is write a method which accepts a String array, loop through the array, in addition to appends each chemical constituent into StringBuilder. Once done, render the String from StringBuilder past times calling the toString() method.

Here is 1 of such method:

public static String toCSV(String[] array) {         String result = "";          if (array.length > 0) {             StringBuilder sb = new StringBuilder();              for (String second : array) {                 sb.append(s).append(",");             }              result = sb.deleteCharAt(sb.length() - 1).toString();         }         return result; }

One of the affair which I don't similar most this code is that I demand to delete the final character because when you lot iterate over an array, you lot terminate upwards adding a comma subsequently the final chemical constituent unless you lot are checking its final chemical constituent inwards each iteration, which is a uncomplicated waste materials of CPU. Do you lot know whatsoever agency to brand this code better? maybe past times removing the final trace of deleting final character.

2) Using  Java 8
This is the most elegant agency to convert an array to String inwards Java. The exclusively grab is that you lot demand to last on JDK 1.8, which is fine for writing examine code but non many companies are using JDK 8 for production code yet.

The join() method is overloaded in addition to allows you lot to bring together multiple String past times leveraging the varargs argument feature. Just transcend a release of String in addition to the delimiter you lot desire to combine them, equally shown below

String message = String.join("-", "Java", "is", "best"); // "Java-is-best"

But, the version nosotros volition utilisation hither is the other one, which accepts an Iterable in addition to a delimiter. Since array implements Iterable inwards Java (remember enhanced for loop), you lot tin utilisation this method to convert an array or collection to delimited String equally shown below:

String csv = String.join(",", new String[]{"a", "b"}); // a,b

Here is the Java plan to demonstrate how to bring together Strings inwards Java from array:

import java.util.Arrays;  /*  * Java Program to bring together Strings using a delimeter  */  public class Java8Demo {      public static void main(String args[]) {          String[] supportedPhones = {"iPhone", "Samsung Galaxy", "iPad"};         String models = String.join(",", supportedPhones);          System.out.println("array: " + Arrays.toString(supportedPhones));         System.out.println("string: " + models);      }  }  Output array: [iPhone, Samsung Galaxy, iPad] string: iPhone,Samsung Galaxy,iPad

Java 8 is amount of such novel features which volition brand coding much to a greater extent than pleasant. If you lot receive got even thus to start alongside Java 8 thus convey about fourth dimension to read Java SE 8 for Really Impatient past times Cay S. Horstmann, 1 of the best books to larn novel features of Java 8 including lambdas, stream, novel appointment in addition to fourth dimension in addition to several others.

3) Using Apache Commons
The tertiary selection is to utilisation the Apache Commons library. This is a full general purpose library which provides many utility functions, recall nosotros receive got used it inwards past times for checking blank or empty String. Most of the fourth dimension you lot volition respect that your projection already using this library. If that's the instance thus only utilisation the StringUtils.join() method to convert a String array to CSV string equally shown below

StringUtils.join(cities, ','); 

Similar to Java 8 bring together method, you lot tin equally good define your ain delimiters e.g. pipe, colon or tab.

4) Using Spring Framework
Spring is 1 of the most pop Java framework in addition to most of the novel development  I receive got done uses Spring for their dependency injection feature. If you lot hand off to utilisation the Spring framework similar many others than you lot tin utilisation it's StringUtils course of didactics to convert an array to String equally shown below. It's real similar to the example, I receive got explained before for converting a collection to String inwards Java.

All you lot demand to is utilisation the org.springframework.util.StringUtils.arrayToCommaDelimitedString(String[] array) method. You tin transcend String array in addition to it volition render a CSV String.


That's all most how to convert an array to a comma-separated String inwards Java. Ideally, you lot should non utilisation whatsoever third-party library for such a uncomplicated trace of piece of occupation but if you lot are already using it thus it equally good doesn't brand feel to reinvent the wheel. Use the get-go selection if you lot are non using Apache Commons or Spring Framework, utilisation the instant selection if you lot are running on Java 8 in addition to utilisation the tertiary or quaternary selection if you lot already subject on Apache park or Spring framework.

Further Learning
Data Structures in addition to Algorithms: Deep Dive Using Java
Algorithms in addition to Data Structures - Part 1 in addition to 2
Data Structures inwards Java nine past times Heinz Kabutz

Sumber https://javarevisited.blogspot.com/

Share this post