Reading and Writing Properties file in Java

Reading and Writing Properties file Java

import java.io.FileInputStream;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

public class App
{
    @SuppressWarnings("rawtypes")
public static void main( String[] args )
    {
    
     Properties prop = new Properties();
        try {
         // Loading Property file
         // This method to load file in Simple Java Application.
                prop.load(new FileInputStream("messages.properties"));
                
                // This method to load file when developing web application
                //prop.load(this.getClass().getClassLoader().getResourceAsStream("messages.properties"));
                
                // Start ::
                //Writing Content to Property file
                prop.setProperty("ID121", "Angad Yadav");
                prop.setProperty("ID122", "Manish Sharma");
                prop.setProperty("ID123", "Sunil Sharma");
                // End ::
                
                // Start ::
                // Reading Content from Property file
                Set set = prop.entrySet();
                Iterator it = set.iterator();
                while (it.hasNext())
                {
                 Map.Entry me = (Map.Entry) it.next();
                 System.out.println("Key====>"+me.getKey() +"===Value===>"+me.getValue());
}
                //End ::
        } catch (Exception e)
        {
         e.printStackTrace();
        }
    }
}

Save this messages.properties file in your project or create new .properties file

1. messages.properties

NotEmpty.validationForm.userName=User Name must not be blank.
Size.validationForm.userName=User Name must between 1 to 20 characters.
NotEmpty.loginForm.userName=must not be blank.
Size.loginForm.userName=size must between 1 to 50 characters.
NotEmpty.loginForm.password=must not be blank.
Size.loginForm.password=size must between 1 to 20 characters.
NotEmpty.registration.password=Password must not be blank.
Size.registration.password=Password must between 4 to 20 characters.
message = HelloWorld

******* Result******