How to convert string to string in java

Java String Array to String

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Today we will look into how to convert Java String array to String. Sometimes we have to convert String array to String for specific requirements. For example; we want to log the array contents or we need to convert values of the String array to String and invoke other methods.

Java String Array to String

Most of the time we invoke toString() method of an Object to get the String representation. Let’s see what happens when we invoke toString() method on String array in java.

Below image shows the output produced by the above program. The reason for the above output is because toString() call on the array is going to Object superclass where it’s implemented as below.

Java String Array to String Example

So how to convert String array to String in java. We can use Arrays.toString method that invoke the toString() method on individual elements and use StringBuilder to create String.

We can also create our own method to convert String array to String if we have some specific format requirements. Below is a simple program showing these methods in action and output produced.

So if we use array toString() method, it returns useless data. Java Arrays class provide toString(Object[] objArr) that iterates over the elements of the array and use their toString() implementation to return the String representation of the array. That’s why when we use this function, we can see that it’s printing the array contents and it can be used for logging purposes. If you want to combine all the String elements in the String array with some specific delimiter, then you can use convertStringArrayToString(String[] strArr, String delimiter) method that returns the String after combining them.

Java Array to String Example

Now let’s extend our String array to String example to use with any other custom classes, here is the implementation.

Output produced by the above java array to String example program is;

So we looked at how to convert Java String array to String and then extended it to use with custom objects. That’s all for converting java array to String.

You can checkout more core java examples from our GitHub Repository.

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Java String Array to String

While we believe that this content benefits our community, we have not yet thoroughly reviewed it. If you have any suggestions for improvements, please let us know by clicking the “report an issue“ button at the bottom of the tutorial.

Today we will look into how to convert Java String array to String. Sometimes we have to convert String array to String for specific requirements. For example; we want to log the array contents or we need to convert values of the String array to String and invoke other methods.

Java String Array to String

Most of the time we invoke toString() method of an Object to get the String representation. Let’s see what happens when we invoke toString() method on String array in java.

Below image shows the output produced by the above program. The reason for the above output is because toString() call on the array is going to Object superclass where it’s implemented as below.

Java String Array to String Example

So how to convert String array to String in java. We can use Arrays.toString method that invoke the toString() method on individual elements and use StringBuilder to create String.

We can also create our own method to convert String array to String if we have some specific format requirements. Below is a simple program showing these methods in action and output produced.

So if we use array toString() method, it returns useless data. Java Arrays class provide toString(Object[] objArr) that iterates over the elements of the array and use their toString() implementation to return the String representation of the array. That’s why when we use this function, we can see that it’s printing the array contents and it can be used for logging purposes. If you want to combine all the String elements in the String array with some specific delimiter, then you can use convertStringArrayToString(String[] strArr, String delimiter) method that returns the String after combining them.

Java Array to String Example

Now let’s extend our String array to String example to use with any other custom classes, here is the implementation.

Output produced by the above java array to String example program is;

So we looked at how to convert Java String array to String and then extended it to use with custom objects. That’s all for converting java array to String.

You can checkout more core java examples from our GitHub Repository.

Want to learn more? Join the DigitalOcean Community!

Join our DigitalOcean community of over a million developers for free! Get help and share knowledge in our Questions & Answers section, find tutorials and tools that will help you grow as a developer and scale your project or business, and subscribe to topics of interest.

How convert an array of Strings in a single String in java?

Using StringBuffer

Create an empty String Buffer object.

Traverse through the elements of the String array using loop.

In the loop, append each element of the array to the StringBuffer object using the append() method.

Finally convert the StringBuffer object to string using the toString() method.

Example

Output

Using the toString() method of the Arrays class

The toString() method of the Arrays class accepts a String array (in fact any array) and returns it as a String. Pass your String array to this method as a parameter.

Example

Output

Using the StringJoiner class

Since Java8 StringJoiner class is introduced this you can construct a sequence of characters separated by desired delimiter.

The add() method accepts a CharacterSequence object (Segment, String, StringBuffer, StringBuilder) and adds it to the current Joiner separating the next and previous elements (if any) with delimiter at the time of constructing it.

The toString() method returns the contents of the current StringJoiner as a Sting object.

Therefore, to convert String array to a single Sting using this class −

Create an object of StringJoiner.

Traverse through the Sting array using a loop.

In the loop add each element of the Sting array to the StringJoiner object.

Convert the it to String using the toSting() method.

How to Convert Array to String in Java

Azhwani • Jun 11, 2021 • java • 8 mins read

Table of Contents [ Show ]

In this quick tutorial, we’re going to look at different ways to convert an array to String in Java.

We often need to convert an array or a list of strings into one single String to meet some basic programming needs.

For example, sometimes, we may want to join multiple strings separated by a comma to create a CSV String.

Feel free to check our article on how to convert a string into an array to learn how to do the opposite.

Converting Array to String in Java

Basically, converting an array of elements to a string is very easy and can be done using multiple strategies and methods. However, unfortunately, there is no direct way to achieve that in Java.

Now you may be wondering, why we can’t just use the toString() method, since arrays are considered objects in Java.

Well, if you try to invoke toString() on an array, you will get something like [C@15db9742 as output.

Not cool right? It’s not even a human-understandable result.

Using String.join() Method

join() belongs to String class and it can be used to join string array to produce one single String instance.

This method returns a new String composed of CharSequence elements joined together with the help of the specified delimiter.

In this example, we are going to use the join() method to create a new string object from an array.

Using Arrays.toString()

Arrays.toString() is a built-in method of Arrays utility class and it provides the simplest way to turn an Array into a String.

It simply returns the string representation of the specified array. All array’s elements will be separated by “,” and enclosed in square brackets “[]“.

Let’s see how we can use Arrays.toString() method to produce a single string from an array of strings:

Using StringBuilder append() Method

StringBuilder class can be used to create mutable string objects. It offers the append(String str) method to append a given string to the sequence.

StringBuilder.toString() returns the string representation of the data encapsulated in the StringBuilder object.

In order to use StringBuilder to convert an array to string in Java, we need to follow the following steps:

Create a StringBuilder object

Iterate over the array

Use toString() method to return a string instance from the stringBuilder object.

Using StringJoiner class

StringJoiner is a new class introduced in Java 8, it belongs to the java.util package. It provides methods for joining multiple Strings into one single string object using a specified delimiter.

StringJoiner offers a fluent way to join strings, we can chain the calls and write code in one line.

For example, we can use it to join multiple strings separated by “/” to create a full path for a directory in Centos:

Java 8 Stream API

The joining() method is defined in Collectors class, it is mainly used to convert multiple strings to a string object.

In general, Collectors class provides 3 overloaded static methods to perform string joining operations.

Let’s see with an example how we can use Collectors.joining() to concatenate multiple strings to form one string:

Using StringUtils (Apache Commons)

StringUtils class from Apache Commons Lang library, offers multiple handy methods for handling string related operations.

It provides multiple join() methods that we can use to convert an array of strings to a single string in Java.

In order to use this class, we will need to add commons-lang3 dependency to our dependency management tool file (pom.xml in case of Maven):

The following example shows how to create a new string from an array using StringUtils.join():

Using Guava Joiner Class

Joiner (a class provided by Guava library) provides clean and concise syntax to handle string concatenation. It takes multiple strings and concatenates them together using delimiters.

Like the Splitter class, Joiner comes with interesting built-in utility methods such as skipNulls which can be used to skip and ignore null values.

To demonstrate this, let’s use the Joiner class to produce a comma separated string from an array:

Using Own Implementation

In case you don’t want to use all the above methods for some reason or another, we can always create our own implementation.

Here is an example that shows how to define a customized implementation for converting an array to string in Java.

How to Convert char Array to String in Java?

There are multiple ways to convert a char array (char[]) to a String in Java. Below, are the list of methods for converting char[] array to a string object.

Using String Constructor

String class provides an overloaded constructor that accepts a char array as an argument. Using a constructor is the most logical and easiest way to create a string from a char array.

All we need to do is passing the array as a parameter to the String constructor and we are done.

Using StringBuilder

StringBuilder is yet another simple way to produce a new string from a char[] array.

It provides the append() method which can be used to construct a single string from every character of the array.

The conversion logic is very simple:

Create a new StringBuilder instance.

Iterate over the array of characters.

Use append() method to add every character.

Use toString() method to get String object.

Using Arrays.stream()

Java 8 provides another pretty good solution to create a new string from a character array. We can use Arrays.stream() method to create a stream over an array of characters.

Then, we can use the joining() method of the Collectors class to create the String.

Let’s look at the following example:

Using valueOf(char[] data) and copyValueOf(char[] data)

The valueOf() method returns the string representation of the passed argument.

The String class has an overloaded static method: String.valueOf(char [] chars), which takes a char[] as an argument and returns a new string containing all the characters of the passed array.

copyValueOf(char[] data) method serves the same purpose as valueOf(). The two methods are equivalent according to javadocs.

Conclusion

That’s all folks! In this article, we have explored possible ways to convert an array to a String in Java.

Happy Learning! If you have any questions, please leave a note in the comments section.

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