Demonstrates class Properties of the java.util package. - Java File Path IO

Java examples for File Path IO:Property Files

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Description

Demonstrates class Properties of the java.util package.

Demo Code

import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;
import java.util.Set;

public class Main  
{
   public static void main(String[] args)
   {//from  w w  w  .ja v a2s .  com
      Properties table = new Properties(); 

      // set properties
      table.setProperty("color", "blue");
      table.setProperty("width", "200");

      System.out.println("After setting properties");
      listProperties(table); 

      // replace property value
      table.setProperty("color", "red");

      System.out.println("After replacing properties");
      listProperties(table); 

      saveProperties(table);

      table.clear(); // empty table

      System.out.println("After clearing properties");
      listProperties(table); 
      
      loadProperties(table);

      // get value of property color
      Object value = table.getProperty("color");

      // check if value is in table
      if (value != null)
         System.out.printf("Property color's value is %s%n", value);
      else
         System.out.println("Property color is not in table");
   } 

   // save properties to a file
   private static void saveProperties(Properties props)
   {
      // save contents of table
      try
      {
         FileOutputStream output = new FileOutputStream("props.dat");
         props.store(output, "Sample Properties"); // save properties
         output.close();
         System.out.println("After saving properties");
         listProperties(props); 
      } 
      catch (IOException ioException)
      {
         ioException.printStackTrace();
      } 
   } 

   // load properties from a file
   private static void loadProperties(Properties props)
   {
      // load contents of table
      try
      {
         FileInputStream input = new FileInputStream("props.dat");
         props.load(input); // load properties
         input.close();
         System.out.println("After loading properties");
         listProperties(props); 
      } 
      catch (IOException ioException)
      {
         ioException.printStackTrace();
      } 
   } 

   // output property values
   private static void listProperties(Properties props)
   {
      Set<Object> keys = props.keySet(); // get property names
 
      // output name/value pairs
      for (Object key : keys)
         System.out.printf(
            "%s\t%s%n", key, props.getProperty((String) key));

      System.out.println();
   } 
}

Result


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