How do I convert ResourceBundle to Map?

By Wayan in Core API, Util Package 1 Comment

The following code snippet will convert a resource bundle into a map object, a key-value mapping. It will read from a file called Messages_en_GB.properties which corresponding to the Locale.UK. For example the file contain the following string. This file should be placed under the resources directory.

welcome.message = Hello World!

package org.kodejava.util;

import java.util.*;

public class ResourceBundleToMap {
    public static void main(String[] args) {
        // Load resource bundle Messages_en_GB.properties from the classpath.
        ResourceBundle resource = ResourceBundle.getBundle("Messages", Locale.UK);

        // Call the convertResourceBundleTopMap method to convert the resource
        // bundle into a Map object.
        Map<String, String> map = convertResourceBundleToMap(resource);

        // Print the entire contents of the Map.
        for (String key : map.keySet()) {
            String value = map.get(key);
            System.out.println(key + " = " + value);
        }
    }

    /**
     * Convert ResourceBundle into a Map object.
     *
     * @param resource a resource bundle to convert.
     * @return Map a map version of the resource bundle.
     */
    private static Map<String, String> convertResourceBundleToMap(ResourceBundle resource) {
        Map<String, String> map = new HashMap<>();
        Enumeration<String> keys = resource.getKeys();
        while (keys.hasMoreElements()) {
            String key = keys.nextElement();
            map.put(key, resource.getString(key));
        }
        return map;
    }
}

How do I convert LinkedList to array?

By Wayan in Core API, Util Package 0 Comment 
package org.kodejava.util;

import java.util.LinkedList;
import java.util.List;

public class LinkedListToArray {
    public static void main(String[] args) {
        List<String> list = new LinkedList<>();
        list.add("Blue");
        list.add("Green");
        list.add("Purple");
        list.add("Orange");

        // Converting LinkedList to array can be done by calling the toArray()
        // method of the List;
        String[] colors = new String[list.size()];
        list.toArray(colors);

        for (String color : colors) {
            System.out.println("color = " + color);
        }
    }
}

How do I get all available timezones?

By Wayan in Core API, Util Package 0 Comment 
package org.kodejava.util;

import java.util.TimeZone;

public class TimezonesExample {
    public static void main(String[] args) {
        String[] availableTimezones = TimeZone.getAvailableIDs();

        for (String timezone : availableTimezones) {
            System.out.println("Timezone ID = " + timezone);
        }
    }
}

Some examples of the returned timezones ids are:

Timezone ID = Etc/GMT+12
Timezone ID = Etc/GMT+11
Timezone ID = MIT
Timezone ID = Pacific/Apia
Timezone ID = Pacific/Midway
Timezone ID = Pacific/Niue
Timezone ID = Pacific/Pago_Pago
Timezone ID = Pacific/Samoa
Timezone ID = US/Samoa
...

How do I get currency symbol?

By Wayan in Core API, Util Package 1 Comment 
package org.kodejava.util;

import java.util.Currency;
import java.util.Locale;

public class CurrencySymbol {
    public static void main(String[] args) {
        Currency currency = Currency.getInstance(Locale.JAPAN);
        System.out.println("Japan = " + currency.getSymbol());

        currency = Currency.getInstance(Locale.UK);
        System.out.println("UK = " + currency.getSymbol());

        currency = Currency.getInstance(Locale.US);
        System.out.println("US = " + currency.getSymbol());

        currency = Currency.getInstance(new Locale("in", "ID"));
        System.out.println("Indonesia = " + currency.getSymbol());
    }
}

The result of the code snippet above:

Japan = ¥
UK = £
US = $
Indonesia = IDR

How do I sort items in a Set?

By Wayan in Core API, Util Package 0 Comment

The trick to sort a java.util.Set is to use the implementation of a java.util.SortedSet such as the java.util.TreeSet class. The example below shows you the result of using the java.util.TreeSet class, in which the items in it will be sorted based on the element’s natural order.

package org.kodejava.util;

import java.util.Set;
import java.util.TreeSet;

public class TreeSetDemo {
    public static void main(String[] args) {
        // The TreeSet class is an implementation of a SortedSet, this means
        // that when you are using the TreeSet to store you data collections
        // you'll get the items ordered base on its elements natural order.
        Set<String> set = new TreeSet<>();

        // In the example below we add some letters to the TreeSet, this mean
        // that the alphabets will be ordered based on the alphabet order
        // which is from A to Z.
        set.add("Z");
        set.add("A");
        set.add("F");
        set.add("B");
        set.add("H");
        set.add("X");
        set.add("N");

        for (String item : set) {
            System.out.print(item + " ");
        }
    }
}

This demo prints:

A B F H N X Z