Java ResourceBundle containsKey() Method

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Description

The java ResourceBundle containsKey(String key) method determines whether the given key is contained in this ResourceBundle or its parent bundles.

Declaration

Following is the declaration for java.util.ResourceBundle.containsKey() method

public boolean containsKey(String key)

Parameters

key − the resource key

Return Value

This method returns true if the given key is contained in this ResourceBundle or its parent bundles; false otherwise.

Exception

NullPointerException − if key is null

Checking Key to Exist in a Resource Bundle of US Locale

The following example shows the usage of Java ResourceBundle containsKey() method to check if a key is present in the resource bundle or not. We've created a resource bundle of US Locale for the corresponding hello_en_US.properties file. Then we printed the text assigned to key hello. Using containsKey() method, we checked if keys "bye" and "hello" are present or not.

package com.tutorialspoint;

import java.util.Locale;
import java.util.ResourceBundle;

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

      // create a new ResourceBundle with specified locale
      ResourceBundle bundle = ResourceBundle.getBundle("hello", Locale.US);

      // print the text assigned to key "hello"
      System.out.println(bundle.getString("hello"));

      // check if the bundle contains "bye" key
      System.out.println(bundle.containsKey("bye"));

      // check if the bundle contains "hello" key
      System.out.println(bundle.containsKey("hello"));
   }
}

Output

Assuming we have a resource file hello_en_US.properties available in your CLASSPATH, with the following content. This file will be used as an input for our example program −

hello = Hello World!

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

Hello World!
false
true

Checking Key to Exist in a Resource Bundle of FRANCE Locale

The following example shows the usage of Java ResourceBundle containsKey() method to check if a key is present in the resource bundle or not. We've created a resource bundle of French Locale for the corresponding hello_fr_FR.properties file. Then we printed the text assigned to key hello. Using containsKey() method, we checked if keys "bye" and "hello" are present or not.

package com.tutorialspoint;

import java.util.Locale;
import java.util.ResourceBundle;

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

      // create a new ResourceBundle with specified locale
      ResourceBundle bundle = ResourceBundle.getBundle("hello", Locale.FRANCE);

      // print the text assigned to key "hello"
      System.out.println(bundle.getString("hello"));

      // check if the bundle contains "bye" key
      System.out.println(bundle.containsKey("bye"));

      // check if the bundle contains "hello" key
      System.out.println(bundle.containsKey("hello"));
   }
}

Output

Assuming we have a resource file hello_fr_FR.properties available in your CLASSPATH, with the following content. This file will be used as an input for our example program −

hello = Bonjour le monde!

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

Bonjour le monde!
false
true

Checking Key to Exist in a Resource Bundle of GERMANY Locale

The following example shows the usage of Java ResourceBundle containsKey() method to check if a key is present in the resource bundle or not. We've created a resource bundle of German Locale for the corresponding hello_de_DE.properties file. Then we printed the text assigned to key hello. Using containsKey() method, we checked if keys "bye" and "hello" are present or not.

package com.tutorialspoint;

import java.util.Locale;
import java.util.ResourceBundle;

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

      // create a new ResourceBundle with specified locale
      ResourceBundle bundle = ResourceBundle.getBundle("hello", Locale.GERMANY);

      // print the text assigned to key "hello"
      System.out.println(bundle.getString("hello"));

      // check if the bundle contains "bye" key
      System.out.println(bundle.containsKey("bye"));

      // check if the bundle contains "hello" key
      System.out.println(bundle.containsKey("hello"));
   }
}

Output

Assuming we have a resource file hello_de_DE.properties available in your CLASSPATH, with the following content. This file will be used as an input for our example program −

hello = Hallo Welt!

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

Hallo Welt!
false
true