How to create and modify Properties file form Java program in Text and XML format

Though most of the time we create and modify properties file using text
editor like notepad, word-pad or edit-plus, It’s also possible to create and edit
properties file from Java program. Log4j.properties, which is
used to configure Log4J based logging
in Java and jdbc.properties which is used to specify configuration
parameters for database
connectivity using JDBC are two most common example of property file in
Java. Though I have not found any real situation where I need to create
properties file using Java program but it’s always good to know about
facilities available in Java API. In last Java tutorial on Properties we have
seen how
to read values from properties file on both text and XML format and in this
article we will see how to create properties file on both text and XML format.
Java API’s java.util.Properties class provides several utility store() methods to
store properties in either text or xml format. Store() can be
used to store property in text properties file and  storeToXML() method can
be used for creating a Java property file in XML format.

Java
program to create and store Properties in text and XML format

As I said earlier java.util.Properties represent property file in
Java program. It provides load() and store() method to
read and write properties files from and to File system. Here is simple example
of creating Java property file form program itself.

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.util.Properties;



/**

 * Java program to create and modify property file in text format
and storing

 * property
on it. Most of the time we use text editor to create and edit property

 * file e.g. jdbc.properties
or log4j.properties but we can also create property

 * file from
Java program as shown in this example.

 *

 * @author Javin Paul

 */

public class
TextPropertyWriter {



    public static void
main(String args[]) throws
FileNotFoundException, IOException {



        //Creating
properties files from Java program

        Properties props = new Properties();

        FileOutputStream fos = new FileOutputStream("c:/user.properties");

     

        props.setProperty("key1",
"value1");

        props.setProperty("key2",
"value2");

     

        //writing properites
into properties file from Java

        props.store(fos, "Properties
file generated from Java program");

     

        fos.close();

     

    }

}

This will create user.properties file in C:\. here is how that property
file will look like:

#Properties file generated from Java program

#Mon Jan 16 03:00:57 VET 2012

key2=value2

key1=value1

Here is another example of creating Java property file in XML format from
Java program:

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.util.Properties;



/**

 * Java program to store properties in XML property file. stroeToXML()
method of

 * java.util.Properties
class is used to save properties in XML property file from Java

 * program.

 *

 * @author Javin Paul

 */

public class
XmlPropertiesWriter {



    public static void
main(String args[]) throws
FileNotFoundException, IOException {



        //Reading properties
files in Java example

        Properties props = new Properties();

        FileOutputStream fos = new FileOutputStream("c:/user.xml");

     

        props.setProperty("key1",
"value1");

        props.setProperty("key2",
"value2");

     

        //writing properites
into properties file from Java

        props.storeToXML(fos, "Properties
file in xml format generated from Java program");

     

        fos.close();



     

    }

}

Output:

version="1.0" encoding="UTF-8" standalone="no"?>

"http://java.sun.com/dtd/properties.dtd">



Properties file
in xml format generated from Java program


key="key2">value2


key="key1">value1

That’s all on How to create Properties file from Java program or How to
modify Properties from Java program. As I said almost all time we use text
editor e.g. notepad or notepad++ to edit properties file like log4j.properties or jdbc.properties, you can
also edit them from Java program if needed. I personally prefer properties
file in text format if number of properties is not much and XML based
properties file if file is big enough e.g. if you have many properties to
leverage XML editors.

Other Java XML tutorials you may find useful

How
to read XML files using SAX parser in Java

How
to parse XML documents with DOM parser in Java with Example

Difference
between DOM and SAX parser in Java

Reading
and Writing XML documents using JDOM parser
Example

How
to replace XML special characters from String in Java

Source:http://javarevisited.blogspot.com/2012/12/how-to-create-and-modify-properties.html