What is StringUtils.prependIfMissing in Java?
prependIfMissing is a StringUtils class that is used to prepend a given prefix at the beginning of a string if it does not already end with one on the given list.
This method is case-sensitive, which means it checks whether the string starts with the given list of prefixes.
For a case-insensitive method with the same functionality, refer to this shot.
How to import StringUtils
The definition of StringUtils can be found in the Apache Commons Lang package, which we can add to the Maven project by adding the following dependency to the pom.xml file:
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.12.0</version>
</dependency>
For other versions of the
commons-langpackage, refer to the Maven Repository.
You can import the StringUtils class as follows:
import org.apache.commons.lang3.StringUtils;
Syntax
public static String prependIfMissing(final String str, final CharSequence prefix, final CharSequence... prefixes)
Parameters
The function takes the following parameters:
final String stris the string to check and prepend.final CharSequence prefixis the prefix to prepend to the string.final CharSequence... prefixesis the list of prefixes that are valid.
Return value
The return value is a new string with the prefix prepended. Otherwise, the same string will be returned in case the string starts with any of the prefixes.
Code
import org.apache.commons.lang3.StringUtils;public class Main{public static void main(String[] args){String beforePrepending = "educative";String prefix = "hello-";System.out.println(StringUtils.prependIfMissing(beforePrepending, prefix, "hello", "tive"));System.out.println(StringUtils.prependIfMissing(beforePrepending, prefix, "hello", "educat", "tive"));}}
Explanation
String = "educative"Prefix = "-edpresso"Prefixes list = ["hello", "tive"]
The function would prepend the prefix to the string and return hello-educative, because the string does not start with any of the values in the prefixes list.
String = "educative"Prefix = "-edpresso"Prefixes list = ["hello", "educat", "tive"]
The function would not prefix the prefix to the string and returns the same input string educative, because the string starts with the "educat" value in the prefixes list.
Output
The output of the code will be as follows:
hello-educative
educative
Free Resources
- undefined by undefined
- undefined by undefined
