How to use Java properties file

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

public class Greeting2
{
           String message;

          // class constructor

           public Greeting2()
           {

           }

     public void setMessage()
     {

          //create an instance of properties class

          Properties props = new Properties();

          //try retrieve data from file

             try {

             props.load(new FileInputStream("message.properties"));

             message = props.getProperty("message");

             System.out.println(message);
              }

             //catch exception in case properties file does not exist

             catch(IOException e)
             {
             e.printStackTrace();
             }
     }

     public static void main(String[] args)
     {
     //create an instance of greeting2 class

     Greeting2 gr = new Greeting2();

     //call the setMessage() method of the Greeting2 class

     gr.setMessage();

     }
}     //end of source code file

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

public class Greeting3
{
     String message;

           public Greeting3()
          {

          }

     public void setMessage()
     {

     //create an instance of properties class

     Properties props = new Properties();

     //try retrieve data from file
     //catch exception in case properties file does not exist

               try {

               props.load(new FileInputStream("message.properties"));

               message = props.getProperty("message");

             //If value of message variable is null assign default value "Hello World"

             if(message==null)
               {
               message=new String("Hello World!");
               }

     System.out.println(message);

     }

     //catch exception in case properties file does not exist

     catch(IOException e)
     {
     e.printStackTrace();
     }
   }

     public static void main(String[] args)
     {
     //create an instance of Greeting3 class

     Greeting3 gr = new Greeting3();

     //call the setMessage() method of the Greeting3 class

     gr.setMessage();

     }

   }

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

public class Greeting4
{

     String message;

          public Greeting4()
           {
           message= new String("Hello World");
           }

     public void setMessage()
     {

     //create an instance of properties class

     Properties props = new Properties();

     //try retrieve data from file

               try {

               props.load(new FileInputStream("message.properties"));

               // assign value to message variable only if it is not null

                  if(props.getProperty("message") !=null)
                    {
                    message = props.getProperty("message");
                    }

     System.out.println(message);
     }

               //catch exception in case properties file does not exist

               catch(IOException e)
               {
                   System.out.println(message);
                   }
     }

     public static void main(String[] args)
     {
     //create an instance of Greeting4 class

     Greeting4 gr = new Greeting4();

     //call the setMessage() method of the Greeting4 class

     gr.setMessage();
     }
 }