Java Properties File

Java properties file are use to read project configuration/ utility configuration. Suppose you have a utility which queries the database, for that you may need Username, Password, Hostname which is useful when using a java properties file.
In this tutorial things covered are
1. How to create a property file
2. How to write to property file
3. How to read from property file with key
4. How to read all keys and values from property file

 package Java.property.file;  
 import java.io.BufferedInputStream;  
 import java.io.BufferedOutputStream;  
 import java.io.File;  
 import java.io.FileInputStream;  
 import java.io.FileNotFoundException;  
 import java.io.FileOutputStream;  
 import java.io.IOException;  
 import java.io.InputStream;  
 import java.util.Enumeration;  
 import java.util.Properties;  
 public class PropertyFileExample01 {  
      public static void main(String[] args) {  
           new PropertyFileExample01().setProperties();  
           new PropertyFileExample01().getProperies();  
           new PropertyFileExample01().readAllFromProperties();  
      }  
      // write to the properties file  
      public void setProperties() {  
           /*  
            * and if you want to create the file sudas.properties file.CreateFile  
            * something to do  
            */  
           File file = new File("/Users/S_Das/git/project.chanko/sudas.properties");  
           try {  
                BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));  
                Properties prop = new Properties();  
                prop.setProperty("hostname", "testHostName");  
                prop.setProperty("username", "testUserName");  
                prop.setProperty("password", "testPassword");  
                /*  
                 * writes the property table to the Output stream Parameters: out an  
                 * output stream. comments a description of the property list.  
                 */  
                prop.store(bos, null);  
           } catch (IOException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
           }  
      }  
      // read from the properties file  
      public void getProperies() {  
           // created a file input stream to read the properties file  
           try {  
                BufferedInputStream bis = new BufferedInputStream(  
                          new FileInputStream(new File("/Users/S_Das/git/project.chanko/sudas.properties")));  
                Properties prop = new Properties();  
                // Reads a property list (key and element pairs) from the input byte  
                // stream.  
                prop.load(bis);  
                // get the properties file  
                String hostname = prop.getProperty("hostname");  
                String usernsme = prop.getProperty("username");  
                String password = prop.getProperty("password");  
                System.out.println(hostname + '\t' + usernsme + '\t' + password);  
           } catch (IOException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
           }  
      }  
      // This method is not working not able to find the file from class path  
      /*  
       * public void getPropertiesFromClassPath() {  
       *   
       * InputStream inputStream =  
       * PropertyFileExample01.class.getClassLoader().getResourceAsStream(  
       * "/sudas.properties");  
       *   
       * try { Properties prop = new Properties(); prop.load(inputStream);  
       *   
       * String hostname = prop.getProperty("hostname"); String usernsme =  
       * prop.getProperty("username"); String password =  
       * prop.getProperty("password");  
       *   
       * System.out.println(hostname + '\t' + usernsme + '\t' + password);  
       *   
       * } catch (IOException e) { // TODO Auto-generated catch block  
       * e.printStackTrace(); }  
       *   
       * }  
       */  
      // read everything from a property file  
      public void readAllFromProperties() {  
           Properties prop = new Properties();  
           BufferedInputStream bis;  
           try {  
                bis = new BufferedInputStream(  
                          new FileInputStream(new File("/Users/S_Das/git/project.chanko/sudas.properties")));  
                prop.load(bis);  
           } catch (IOException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
           }  
           Enumeration<?> values = prop.propertyNames();  
           while (values.hasMoreElements()) {  
                String key = values.nextElement().toString();  
                System.out.println("Key : " + key);  
                String value = prop.getProperty(key);  
                System.out.println("Value : " + value);  
           }  
      }  
 }