Java StringJoiner

Java StringJoiner belongs to java.util package(packages are the collection of class and inheritances), with the help of StringJoiner in java we are able to construct sequences of characters and these characters are separated by a delimiter, and it has optional support where we can optionally start with suffix and prefix and also we can do ending with suffix and prefix. You may think why we should use this as we have already StringBuilder in Java, so actually, with the help of StringJoiner, we needed to write very less code with getting better and efficient output result.

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Syntax of Java StringJoiner

Here we have syntax for constructors and for methods both.

a. Constructor based syntax

Given below are constructor based syntax:

1. StringJoiner(SequenceOfCharacters d): It’s a very plain way to use StringJoiner. Here, we are not going to use anything like characters, start prefix, suffix and not end prefix and suffix.

Scope(public/private/protected) StringJoiner(SequenceOfCharacters d)

Attributes:

• d(delimiter): Here, the characters sequences will use a separator of each element value inside the StringJoiner.

2. StringJoiner(SequenceOfCharacters d, CharSequence p, SequenceOfCharacters s): It will use the constructJoiner without any characters by using the copy its supplied (p)prefix, (s)suffix and delimiter. In case if we are not adding any characters for StringJoiner and also if we are not accessing invoked string value, it will perform its default behavior which is its gives result as prefix++suffix in the output result .

Scope(public/private/protected) StringJoiner(SequenceOfCharacters d,
SequenceOfCharacters p, SequenceOfCharacters s)

Attributes:

• d(delimiter): Here, the characters sequences will use a separator of each element value inside the StringJoiner.
• p(prefix): This is the character sequence that is mostly used for the beginning.
• s(suffix): This is the character sequence that is mostly used for the end.

b. Method based syntax

We can use 5 different kinds of syntax for the StringJoiner.

1. String toString(): It will produce a String object from the StringJoiner.

Scope(public/private/protected) String toString()

Attributes:

• NA(no attribute we can see the function)

2. StringJoiner add: This method is used to add a copy of the CharSequence value for the next element to StringJoiner.

Scope(public/private/protected) StringJoiner add(SequenceOfCharacters ne)

Attributes:

• ne(newElement): This is the new element for add.

3. StringJoiner merge: It is used for adding the new contents for the StringJoiner; it happens without using a suffix and prefix in the form of the next element (in case it is non-empty). Suppose if the string given is empty, then this call does not change.

Scope(public/private/protected) StringJoiner merge(StringJoiner other)

Attributes:

• other: This is that StringJoiner where the contents will merge.

4. int length: This method will be used when we want to get the size of the string.

Scope(public/private/protected) int length()

Attributes:

• NA(none of the attribute)

Returns:

It will give this StringJoiner.

5. StringJoiner setEmptyValue: This method allotted a string to be used at the time deciding the string representation of the StringJoiner and time when there was no element inside the string.

Scope(public/private/protected) StringJoiner setEmptyValue(CharSequence emptyValue)

Attributes:

• emptyValue: If we want to get an empty string’s value, then it will be used.

How does Java StringJoiner class work?

• StringJoiner in java is a new feature that was introduced in version 8.
• Util contains all the important classes and inheritance along with StringJoiner.
• At any time, if we wanted to use StringJoiner class, we can get it with import java.util.StringJoiner.
• With the help of the class StringJoiner, we can join many strings along with specifying the delimiter. It also allows us to use prefix and suffix to the output result string at the time of joining many strings.

Examples of Java StringJoiner

Given below are the examples of Java StringJoiner:

Example #1

Here we are joining many usernames, and we are passing “-” as the delimiter between the names.

Code:

import java.util.StringJoiner;
public class JoinString {
public static void main(String[] arguments) {
StringJoiner joinStrings = new StringJoiner("-");
joinStrings.add("Ranjan");
joinStrings.add("Ajay");
joinStrings.add("Vijay");
joinStrings.add("Sujit");
joinStrings.add("Akash");
joinStrings.add("Vikash");
joinStrings.add("Arun");
System.out.println(joinStrings.toString());
}
}

Output:

Example #2

Code:

import java.util.StringJoiner;
public class JoinNumbers{
public static void main(String[] arguments) {
StringJoiner joinNumeric = new StringJoiner(".");
joinNumeric.add("10");
joinNumeric.add("11");
joinNumeric.add("12");
joinNumeric.add("13");
joinNumeric.add("14");
joinNumeric.add("15");
joinNumeric.add("16");
System.out.println(joinNumeric);
}
}

Output:

Conclusion

Here we saw about the StringJoiner class in Java, and we saw about StringJoiner class behaviors with some important examples. We saw various constructors and methods of these StringJoiner classes and working of StringJoiner class in Java.

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