Subclasses must override getContents and provide an array, where each item in the array is a pair of objects. The first element of each pair is the key, which must be a String, and the second element is the value associated with that key.

The following example shows two members of a resource bundle family with the base name "MyResources". "MyResources" is the default member of the bundle family, and "MyResources_fr" is the French member. These members are based on ListResourceBundle (a related example shows how you can add a bundle to this family that's based on a properties file). The keys in this example are of the form "s1" etc. The actual keys are entirely up to your choice, so long as they are the same as the keys you use in your program to retrieve the objects from the bundle. Keys are case-sensitive.

 public class MyResources extends ListResourceBundle {
     protected Object[][] getContents() {
         return new Object[][] {
         // LOCALIZE THIS
             {"s1", "The disk \"{1}\" contains {0}."},  // MessageFormat pattern
             {"s2", "1"},                               // location of {0} in pattern
             {"s3", "My Disk"},                         // sample disk name
             {"s4", "no files"},                        // first ChoiceFormat choice
             {"s5", "one file"},                        // second ChoiceFormat choice
             {"s6", "{0,number} files"},                // third ChoiceFormat choice
             {"s7", "3 Mar 96"},                        // sample date
             {"s8", new Dimension(1,5)}                 // real object, not just string
         // END OF MATERIAL TO LOCALIZE
         };
     }
 }

 public class MyResources_fr extends ListResourceBundle {
     protected Object[][] getContents() {
         return new Object[][] {
         // LOCALIZE THIS
             {"s1", "Le disque \"{1}\" {0}."},          // MessageFormat pattern
             {"s2", "1"},                               // location of {0} in pattern
             {"s3", "Mon disque"},                      // sample disk name
             {"s4", "ne contient pas de fichiers"},     // first ChoiceFormat choice
             {"s5", "contient un fichier"},             // second ChoiceFormat choice
             {"s6", "contient {0,number} fichiers"},    // third ChoiceFormat choice
             {"s7", "3 mars 1996"},                     // sample date
             {"s8", new Dimension(1,3)}                 // real object, not just string
         // END OF MATERIAL TO LOCALIZE
         };
     }
 }
 

The implementation of a ListResourceBundle subclass must be thread-safe if it's simultaneously used by multiple threads. The default implementations of the methods in this class are thread-safe.