How To Convert An Array To Comma Separated String Inward Java

The simplest means to convert an array to comma separated String is to practice a StringBuilder, iterate through the array, in addition to add together each chemical factor of the array into StringBuilder later appending comma. You simply demand Java 1.5 for that, fifty-fifty if yous are non running on Java 5, yous tin utilization StringBuffer inwards house of StringBuilder. The joining of String has got fifty-fifty easier inwards JDK 8, where yous conduct maintain got the join() method correct inwards the String degree itself. The join() method takes a delimiter in addition to a source, which tin hold upwards array or collection in addition to returns a String where each chemical factor is joined past times a delimiter. If yous desire to practice a CSV string, simply transcend comma every bit a delimiter. Btw, these ii methods are non the solely means to practice a comma separated String from an array, yous tin too utilization Apache Commons or Spring framework's utility degree to practice the same.


Now the inquiry comes, why practice yous demand to convert an array to a comma-separated String? Well, in that place tin hold upwards many situations but I'll laissez passer on yous mine. Sometimes back, I was writing roughly JDBC code to shop roughly fields into the database. One of the fields was String array which needs to hold upwards 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 option was to shop comma separated values in addition to and hence I looked into JDK API for whatever method which tin practice that, in that place wasn't any. So, I chop-chop wrote i every bit seen inwards the showtime example. Later, I did a footling fleck of enquiry in addition to come upwards up amongst iv 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 iv examples of converting a String array to CSV text. Though yous tin utilization the same technique in addition to code to practice CSV string from whatever 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 means to hit the task. All yous demand to practice is write a method which accepts a String array, loop through the array, in addition to appends each chemical factor into StringBuilder. Once done, render the String from StringBuilder past times calling the toString() method.

Here is i of such method:

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

One of the affair which I don't similar close this code is that I demand to delete the final character because when yous iterate over an array, yous goal upwards adding a comma later the final chemical factor unless yous are checking its final chemical factor inwards each iteration, which is a uncomplicated waste materials of CPU. Do yous know whatever means to brand this code better? maybe past times removing the final employment of deleting final character.

2) Using  Java 8
This is the most elegant means to convert an array to String inwards Java. The solely grab is that yous demand to hold upwards on JDK 1.8, which is fine for writing evidence code but non many companies are using JDK 8 for production code yet.

The join() method is overloaded in addition to allows yous to bring together multiple String past times leveraging the varargs argument feature. Just transcend a position out of String in addition to the delimiter yous desire to combine them, every bit shown below

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

But, the version nosotros volition utilization hither is the other one, which accepts an Iterable in addition to a delimiter. Since array implements Iterable inwards Java (remember enhanced for loop), yous tin utilization this method to convert an array or collection to delimited String every bit 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 yous conduct maintain nonetheless to start amongst Java 8 in addition to hence convey roughly fourth dimension to read Java SE 8 for Really Impatient past times Cay S. Horstmann, i of the best books to larn novel features of Java 8 including lambdas, stream, novel engagement in addition to fourth dimension in addition to several others.

3) Using Apache Commons
The tertiary option is to utilization the Apache Commons library. This is a full general purpose library which provides many utility functions, recollect nosotros conduct maintain used it inwards past times for checking blank or empty String. Most of the fourth dimension yous volition discovery that your projection already using this library. If that's the illustration in addition to hence simply utilization the StringUtils.join() method to convert a String array to CSV string every bit shown below

StringUtils.join(cities, ','); 

Similar to Java 8 bring together method, yous tin too define your ain delimiters e.g. pipe, colon or tab.

4) Using Spring Framework
Spring is i of the most pop Java framework in addition to most of the novel development  I conduct maintain done uses Spring for their dependency injection feature. If yous tumble out to utilization the Spring framework similar many others than yous tin utilization it's StringUtils degree to convert an array to String every bit shown below. It's real similar to the example, I conduct maintain explained before for converting a collection to String inwards Java.

All yous demand to is utilization 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 close how to convert an array to a comma-separated String inwards Java. Ideally, yous should non utilization whatever third-party library for such a uncomplicated chore but if yous are already using it in addition to hence it too doesn't brand feel to reinvent the wheel. Use the showtime option if yous are non using Apache Commons or Spring Framework, utilization the minute option if yous are running on Java 8 in addition to utilization the tertiary or 4th option if yous already subject on Apache common 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 ix past times Heinz Kabutz

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