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

How do I sort items of an ArrayList?

By Wayan in Core API, Util Package 0 Comment

This example shows you how we can sort items of an ArrayList using the Collections.sort() method. Beside accepting the list object to be sorted we can also pass a Comparator implementation to define the sorting behaviour such as sorting in descending or ascending order.

package org.kodejava.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class ArrayListSortExample {
    public static void main(String[] args) {
        /*
         * Create a collections of colours
         */
        List<String> colours = new ArrayList<>();
        colours.add("red");
        colours.add("green");
        colours.add("blue");
        colours.add("yellow");
        colours.add("cyan");
        colours.add("white");
        colours.add("black");

        /*
         * We can sort items of a list using the Collections.sort() method.
         * We can also reverse the order of the sorting by passing the
         * Collections.reverseOrder() comparator.
         */
        Collections.sort(colours);
        System.out.println(Arrays.toString(colours.toArray()));

        colours.sort(Collections.reverseOrder());
        System.out.println(Arrays.toString(colours.toArray()));
    }
}

The code will output:

[black, blue, cyan, green, red, white, yellow]
[yellow, white, red, green, cyan, blue, black]

How do I sort array values in case-insensitive order?

By Wayan in Core API, Util Package 1 Comment

By default, when sorting an arrays the value will be ordered in case-sensitive order. This example show you how to order it in case-insensitive order.

package org.kodejava.util;

import java.util.Arrays;

public class SortArrayCaseSensitivity {
    public static void main(String[] args) {
        String[] teams = new String[5];
        teams[0] = "Manchester United";
        teams[1] = "chelsea";
        teams[2] = "Arsenal";
        teams[3] = "liverpool";
        teams[4] = "EVERTON";

        // Sort array, by default it will be sorted in case-sensitive order.
        // [Arsenal, EVERTON, Manchester United, chelsea, liverpool]
        Arrays.sort(teams);
        System.out.println("Case sensitive  : " + Arrays.toString(teams));

        // Sort array in case-insensitive order
        // [Arsenal, chelsea, EVERTON, liverpool, Manchester United]
        Arrays.sort(teams, String.CASE_INSENSITIVE_ORDER);
        System.out.println("Case insensitive: " + Arrays.toString(teams));
    }
}

The result of the code snippet above:

Case sensitive  : [Arsenal, EVERTON, Manchester United, chelsea, liverpool]
Case insensitive: [Arsenal, chelsea, EVERTON, liverpool, Manchester United]