Java String join:
The join() method in Java joins the string with the given delimiter and returns an updated string. The first argument passed in this method is a delimiter and the rest of the arguments are the strings that will be joined with the delimiter.
The join() method was introduced as part of the Java8 release.
Method signature:
The signature for a join() method is as shown below.
public static String join(CharSequence delimiter, CharSequence... elements)Method parameters and return type:
Return type: It returns a string joined with a given delimiter
Parameters: It takes CharSequence delimiter and elements as a parameter.
Throws: It throws a NullPointerException if the element of the delimiter is null.
Example 1:
Here we passed a comma as a delimiter and we have joined the rest of the string with it. Let’s check the source to understand this concept.
Source code:
public class Example1 {
public static void main(String args[]) {
String str = String.join(",", "This", "is", "Java", "Tutorial");
System.out.println(str);
}
}
Output:
run:
This,is,Java,Tutorial
BUILD SUCCESSFUL (total time: 1 second)
Example 2:
In case you are passing null as a delimiter, the program will generate a null pointer exception. This example is all about this concept.
Source code:
public class Example2 {
public static void main(String argvs[]) {
String s = String.join(null, "Java", "Tutorial", "Beginner");
System.out.println(s);
}
}
Output:
Exception in thread "main" java.lang.NullPointerException
at java.util.Objects.requireNonNull(Objects.java:203)
at java.lang.String.join(String.java:2451)
at join.Example2.main(Example2.java:15)
C:\Users\Lenovo\AppData\Local\NetBeans\Cache.2\executor-snippets\run.xml:53: Java returned: 1
BUILD FAILED (total time: 3 seconds)
Example 3:
We can pass null as strings that will be joined with the delimiter. The program will treat the null strings normally, and it won’t generate any error.
Source code:
public class Example3 {
public static void main(String argvs[]) {
String s = String.join("/", "Java", "is", null, "of the", "best", " Programming languages ");
System.out.println(s);
}
}
Output:
run:
Java/is/null/of the/best/ Programming languages
BUILD SUCCESSFUL (total time: 1 second)
