How to Load Java Properties File Dynamically From the Classpath

Why this properties file ? if we are using any application where there is a chance of constantly changing any credentials, something consider any java email application or any there you may need to change from,to or any properties right ? In this situation what you have to do is, opening .java file and doing the modifications and again re-compile and re-deploy.  Think what if you need to change 100’s of .java files 🙂 hmm so this .properties file.

We will place this .properties file in general at classpath location, will see how to load that properties file into .java programs and how to use it.

In this application my properties file name  = java4s.properties

Directory Structure

ClientLogic.javva

package java4s;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Properties;

public class ClientLogic {

	public static void main(String... args)
	{

// First Way

		Properties prop = new Properties();
		InputStream inputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("java4s.properties");

		try{
		prop.load(inputStream);
		}catch(IOException e)
		{
			e.printStackTrace();
		}

		System.out.println("------- By Using Thread class -------");
		//Print required values
		System.out.println(prop.get("user"));

		//Print all the properties
		System.out.println(prop);

// Second Way

		URL url = ClassLoader.getSystemResource("java4s.properties");
		try{
		prop.load(url.openStream());
		}catch(Exception e)
		{
			e.printStackTrace();
		}
		System.out.println("------- By Using URL class -------");
	    System.out.println(prop);

	}
}

Output

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::. About the Author .::
		Sivateja Kandula - Java/J2EE Full Stack Developer Founder of Java4s - Get It Yourself, A popular Java/J2EE Programming Blog, Love Java and UI frameworks. You can sign-up for the Email Newsletter for your daily dose of Java tutorials.