How to read properties file in Java.

Apr 08

Reading properties file in Java is much easier than you might have thought. Following example illustrates one simple way of reading properties from a properties file.

Let’s say we need to read from myConfig.properties file.

The properties file has following entries.

Directory = C:/prodFiles/
NumberOfFiles = 25
Extension = java

Here is the java code to read the values of these keys.

import java.util.Properties;
import java.io.*;
public class ReadValues{
   private static final String PROP_FILE="myConfig.properties";
   public void readPropertiesFile(){
       try{
  	     InputStream is = ReadValues.class.getResourceAsStream(PROP_FILE);
	     Properties prop = new Properties();
             prop.load(is);
	     String directory = prop.getProperty("Directory");
             String numberOfFiles = prop.getProperty("NumberOfFiles");
	     String  fileExtension = prop.getProperty("Extension");
             is.close();
	  /* code to use values read from the file*/
       }catch(Exception e){
         System.out.println("Failed to read from " + PROP_FILE + " file.");
       }
   }
  }

The code is quite simple and self explanatory. Let me know if you have any questions.

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Bret
Apr 09, 2008 @ 03:34:04

Well done. I appreciate the fact that you didn’t assume everyone knew how to read in a properties file with Java. It’s a simple task but worth the post. Thanks.

Bret’s last blog post..Windows XP to Remain Available Until 2010

John Doe
May 12, 2008 @ 09:13:04

Thanks!

vivek kumar
Jun 11, 2008 @ 01:12:51

hi coud u plz tell me where u put your .properties file

Zaheer
Jun 11, 2008 @ 20:43:58

Vivek, you can put your properties file in any directory as long as that directory is in your classpath. For e.g; if you save your properties file under C:\resources directory make sure that C:\resources is in your classpath. Or you can put your properties file in the same directory where you have your class file.

Prabhat Atri
Jul 23, 2008 @ 04:01:07

For web applications we can put the .properties file inside your src folder so that after build all the properties file gets reflected/copied to /WEB-INF/classes folder.

To access you can use following code snippet:

Properties props = new Properties();
try
{
ClassLoader cl = UploadDealDocs.class.getClassLoader();
InputStream fin = cl.getResourceAsStream.(“./config.properties”);
props.load(fin);
uploadedFilePath = props.getProperty(“localDrivePath”);
fin.close();
}
catch (Exception e1)
{
LOG.info(“FILE CANNOT BE READ”);
e1.printStackTrace();
}

Cheers

Rashmi
Jul 08, 2009 @ 14:34:34

Is there a different format for reading URL values from the properties file?

My property file has

targetUrl=https://foobar:9080/foo

I am getting a malformed exception error. Do you think I am missing something?

Also, how do we read integer values from the properties file?

Zaheer
Jul 09, 2009 @ 09:27:48

Rashmi, you don’t have to do anything special to read the URL from properties file. Follow the example I provided and you should be able to read the URL from the file. If you can share your code I’ll be glad to help you with malformed exception.
To read an integer value you read the value from the file as String and then convert that value to an int using valueOf method of the Integer class. In my example I read numberOfFiles from the file, here is how you can convert that to an int.
String numberOfFiles = prop.getProperty(“NumberOfFiles”);
int number = Integer.valueOf(numberOfFiles);

Hope this helps, otherwise feel free to contact me directly.

shashi kanth
Dec 06, 2010 @ 03:23:54

Hi Zaheer,
it’s excellent one. i was trying with file input stream as shown below, but application unable to catch the file. getting file not found exception, after replacing these with your above eg. now it is working fine. thank you very much.
and may i know the fault in my below code, y i am getting errror ??

File propsFile = new File(filePath);
FileInputStream fileInputStream = new FileInputStream(propsFile);
prop.load(new FileInputStream(“db.properties”));
System.out.println(“Driver Name : “+prop.getProperty(“driverName”));

SANDHYARAJ
Dec 23, 2010 @ 23:56:19