Java ListResourceBundle getKeys() Method

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Description

The Java ListResourceBundle getKeys() method returns an Enumeration of the keys contained in this ResourceBundle and its parent bundles.

Declaration

Following is the declaration for java.util.ListResourceBundle.getKeys() method

public Enumeration<String> getKeys()

Parameters

NA

Return Value

This method returns an Enumeration of the keys contained in this ResourceBundle and its parent bundles.

Exception

NA

Getting Keys of a ListResourceBundle of String, Integer Pair Example

The following example shows the usage of Java ListResourceBundle getKeys() method to iterate keys of the ListResourceBundle. We've created a ListResourceBundle object having contents an two dimensional array of String, Integer pairs. Then few entries are added by overriding getContents() method and then an enumeration of keys is retrieved and iterated to print the keys.

package com.tutorialspoint;

import java.util.Enumeration;
import java.util.ListResourceBundle;

// create a class that extends to ListResourceBundle
class MyResources extends ListResourceBundle {

   // get contents must be implemented
   protected Object[][] getContents() {
      return new Object[][] {
         {"1", 1},
         {"2", 2},
         {"3", 3}
      };
   }
}

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

      // create a new MyResources instance
      MyResources mr = new MyResources();

      // get the keys
      Enumeration<String> enumeration = mr.getKeys();

      // print the keys
      while (enumeration.hasMoreElements()) {
         System.out.println("" + enumeration.nextElement()); 
      }
   }
}

Output

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

1
2
3

Getting Keys of a ListResourceBundle of String, String Pair Example

The following example shows the usage of Java ListResourceBundle getKeys() method to iterate keys of the ListResourceBundle. We've created a ListResourceBundle object having contents an two dimensional array of String, String pairs. Then few entries are added by overriding getContents() method and then an enumeration of keys is retrieved and iterated to print the keys.

package com.tutorialspoint;

import java.util.Enumeration;
import java.util.ListResourceBundle;

// create a class that extends to ListResourceBundle
class MyResources extends ListResourceBundle {

   // get contents must be implemented
   protected Object[][] getContents() {
      return new Object[][] {
         {"1", "Hello World!"},
         {"2", "Goodbye World!"},
         {"3", "Goodnight World!"}
      };
   }
}

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

      // create a new MyResources instance
      MyResources mr = new MyResources();

      // get the keys
      Enumeration<String> enumeration = mr.getKeys();

      // print the keys
      while (enumeration.hasMoreElements()) {
         System.out.println("" + enumeration.nextElement()); 
      }
   }
}

Output

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

1
2
3

Getting Keys of a ListResourceBundle of String, Object Pair Example

The following example shows the usage of Java ListResourceBundle getKeys() method to iterate keys of the ListResourceBundle. We've created a ListResourceBundle object having contents an two dimensional array of String, Student pairs. Then few entries are added by overriding getContents() method and then an enumeration of keys is retrieved and iterated to print the keys.

package com.tutorialspoint;

import java.util.Enumeration;
import java.util.ListResourceBundle;

// create a class that extends to ListResourceBundle
class MyResources extends ListResourceBundle {

   // get contents must be implemented
   protected Object[][] getContents() {
      return new Object[][] {
         {"1", new Student(1, "Julie")},
         {"2", new Student(2, "Robert")},
         {"3", new Student(3, "Adam")}
      };
   }
}

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

      // create a new MyResources instance
      MyResources mr = new MyResources();

      // get the keys
      Enumeration<String> enumeration = mr.getKeys();

      // print the keys
      while (enumeration.hasMoreElements()) {
         System.out.println("" + enumeration.nextElement()); 
      }
   }
}
class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
}

Output

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

[ 1, Julie ]
[ 2, Robert ]
[ 3, Adam ]