org.apache.commons.lang3.ClassPathUtils Example

Rivu ChakrabortyDecember 25th, 2014Last Updated: January 12th, 2015

0 50 2 minutes read

In this example we are going to elaborate the use of the ClassPathUtils class in the package: org.apache.commons.lang3 or previouslyorg.apache.commons.lang, as the package name says, it is a member of the Apache Commons Lang, and deals with the classpaths. As like other classes of the Apache Commons This class also provides us with some really helpful methods. The methods of this class as other classes of Apache Commons are wrappers for classpath Manipulation so the code which implemented those methods becomes significantly smaller, cleaner and understandable comparing to other programs where those functionalities are written manually.

1. The ClassPathUtils class overview, Fields & Methods.

The ClassPathUtils class in the org.apache.commons.lang3 package is one of the smallest class in the Apache Commons Lang3. It contains just two method with two overloads for each. This class contains no methods or fields. Below you can see the method details and usage.

1.1 The ClassPathUtils Method Summary & Usage

static String toFullyQualifiedName(Class context, String resourceName) : This method returns the fully qualified name for the resource with name resourceName relative to the given context. This method also has a overload in which we can pass the package as the context. Null inputs are not allowed.
Note that this method does not check whether the resource actually exists, it only constructs the name, i.e. if you pass String.class as context and "String.abc" as the resourceName then it will return java..lang.String.abc without checking.
Code
```
System.out.println(ClassPathUtils.toFullyQualifiedName(Math.class,"Math.noClassExists" ));
System.out.println(ClassPathUtils.toFullyQualifiedName(Character.class, "Character.UnicodeBlock"));
System.out.println(ClassPathUtils.toFullyQualifiedName(Reader.class.getPackage(), "FileReader"));
```
Output
```
java.lang.Math.noClassExists
java.lang.Character.UnicodeBlock
java.io.FileReader
```

static String toFullyQualifiedName(Class context, String resourceName) : This method is also same as previous method except that it returns the fully qualified path for the resource with name resourceName relative to the given context. This method also has a overload in which we can pass the package as the context. Null inputs are not allowed.

Code

System.out.println(ClassPathUtils.toFullyQualifiedPath(Math.class,"Math.noClassExists" ));
System.out.println(ClassPathUtils.toFullyQualifiedPath(Character.class, "Character.UnicodeBlock"));
System.out.println(ClassPathUtils.toFullyQualifiedPath(Reader.class.getPackage(), "FileReader"));

Output

java/lang/Math.noClassExists
java/lang/Character.UnicodeBlock
java/io/FileReader

2. ClassPathUtils Example

The complete ClassPathUtilsExample.java

package com.javacodegeeks.example.classpathutilsexample;

import org.apache.commons.lang3.*;

import java.io.*;
import java.util.*;


public class ClassPathUtilsExample {
	public static void main(String args[])
	{
		
		System.out.println(ClassPathUtils.toFullyQualifiedName(Math.class,"Math.noClassExists" ));
		System.out.println(ClassPathUtils.toFullyQualifiedName(Character.class, "Character.UnicodeBlock"));
		System.out.println(ClassPathUtils.toFullyQualifiedName(Reader.class.getPackage(), "FileReader"));
		System.out.println(ClassPathUtils.toFullyQualifiedPath(Math.class,"Math.noClassExists" ));
		System.out.println(ClassPathUtils.toFullyQualifiedPath(Character.class, "Character.UnicodeBlock"));
		System.out.println(ClassPathUtils.toFullyQualifiedPath(Reader.class.getPackage(), "FileReader"));
	}
}

Output

java.lang.Math.noClassExists
java.lang.Character.UnicodeBlock
java.io.FileReader
java/lang/Math.noClassExists
java/lang/Character.UnicodeBlock
java/io/FileReader

Download The Source Code

This was an example for ClassPathUtils in Apache Commons lang3.

Download
You can download the full source code of this example here: ClassPathUtilsExample.zip