Properties Class

Properties Class

In this tutorial, we are going to discuss about Properties Class in java. The Properties class in Java is a subclass of Hashtable<Object, Object> and represents a persistent set of properties that are key-value pairs. It is often used for reading and writing configuration data from/to a file in a simple text format.

Properties Class
  • Properties class is the child class of Hashtable.
  • In our program if anything which changes frequently like Database User name, Password etc., such type of values not recommended to hard code in java application because for every change we have to recompile, rebuild and redeployed the application and even server restart also required sometimes it creates a big business impact to the client.
  • Such type of variable things we have to hard code in property files and we have to read the values from the property files into java application.
  • The main advantage in this approach is if there is any change in property files automatically those changes will be available to java application just redeployment is enough.
  • By using Properties object we can read and hold properties from property files into java application.

Properties p=new Properties();

In properties both key and value “should be String type only”.


1. String getPrperty(String propertyname) ;

Returns the value associated with specified property.

2. String setproperty(String propertyname,String propertyvalue);

To set a new property.

3. Enumeration propertyNames();

4. void load(InputStream is); //Any InputStream we can pass.

To load Properties from property files into java Properties object.

5. void store(OutputStream os,String comment);//Any OutputStream we can pass.

To store the properties from Properties object into properties file.

import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;

 * @author ashok.mariyala
public class MyProperties {
   public static void main(String[] args) throws Exception {
      Properties prop = new Properties();
      FileInputStream fis = new FileInputStream("");
      String url = prop.getProperty("url");
      String username = prop.getProperty("username");
      String password = prop.getProperty("password");
      Connection con = DriverManager.getConnection(url, username, password);
      FileOutputStream fos = new FileOutputStream("");, "Updated by Ashok");
Key Features of Properties
  1. Key-Value Pair Storage: Properties stores data in the form of key-value pairs, where both keys and values are strings.
  2. Loading and Saving: Properties provides methods to load properties from an input stream (e.g., a file) and to store properties into an output stream (e.g., a file). This makes it convenient for managing configuration files.
  3. Default Properties: Properties supports default properties, which are used as defaults when a key is not found in the main properties list.
  4. Persistance: Properties can be persisted to a file using the store() method and later reloaded using the load() method. The file format is simple and human-readable.
  5. Thread Safety: Properties is not synchronized, so concurrent access should be externally synchronized if multiple threads are modifying the properties.

That’s all about the Properties class in java. If you have any queries or feedback, please write us email at Enjoy learning, Enjoy Java.!!

Properties Class
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