187 Java PropertyResourceBundle Class

Introduction

The Java PropertyResourceBundle class is a concrete subclass of ResourceBundle that manages resources for a locale using a set of static strings from a property file.Following are the important points about PropertyResourceBundle −

• The class can be constructed either from an InputStream or a Reader, which represents a property file.

Class declaration

Following is the declaration for java.util.PropertyResourceBundle class −

public class PropertyResourceBundle
   extends ResourceBundle

Field

Fields inherited from class java.util.ResourceBundle.

Class constructors

Sr.No.	Constructor & Description
1	PropertyResourceBundle(InputStream stream) This creates a property resource bundle from an InputStream.
2	PropertyResourceBundle(Reader reader) This creates a property resource bundle from a Reader.

Class methods

Sr.No.	Method & Description
1	Enumeration<String> getKeys() This method returns an Enumeration of the keys contained in this ResourceBundle and its parent bundles.
2	Object handleGetObject(String key) This method gets an object for the given key from this resource bundle.
3	protected Set<String> handleKeySet() This method returns a Set of the keys contained only in this ResourceBundle.

Methods inherited

This class inherits methods from the following classes −

• java.util.ResourceBundle
• java.util.Object

Getting Keys from a PropertyResourceBundle Instance Example

The following example shows the usage of Java PropertyResourceBundle getKeys() method. We created a InputStream of given content and then using that stream a PropertyResourceBundle object is created. Then using getKeys() method, an enumeration of keys is retrieved and entries are printed.

package com.codeheap;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringBufferInputStream;
import java.nio.charset.Charset;
import java.util.Enumeration;
import java.util.PropertyResourceBundle;

public class PropertyResourceBundleDemo {
   public static void main(String[] args) {

      // Prepare content for simulating property files
      String fileContent = 
         "# Integer value 1\n" +
         "s1 = 1\n" +
         "# String value PropertyResourceBundleDemo\n" +
         "s2 = PropertyResourceBundleDemo\n" +
         "# Date value Fri Jan 31 00:00:00 IST 3913\n" +
         "s3 = Fri Jan 31 00:00:00 IST 3913";
      InputStream propStream = new ByteArrayInputStream(fileContent.

   getBytes
         (Charset.forName("UTF-8")));

      try {
      
         // Create property resource bundle
         PropertyResourceBundle bundle = 
         new PropertyResourceBundle(propStream);

         // Get resource keys
         Enumeration<String> keys = bundle.getKeys();

         while(keys.hasMoreElements()) {
            System.out.println("Bundle key: "+keys.nextElement());
         }
      } catch (IOException e) {
         e.printStackTrace();
      }  
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Bundle key: s2
Bundle key: s1
Bundle key: s3