package org.kodejava.util;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.TimeZone;
public class TimeZoneExample {
public static void main(String[] args) {
// Create a calendar object and set it time based on the local
// time zone
Calendar localTime = Calendar.getInstance();
localTime.set(Calendar.HOUR, 17);
localTime.set(Calendar.MINUTE, 15);
localTime.set(Calendar.SECOND, 20);
int hour = localTime.get(Calendar.HOUR);
int minute = localTime.get(Calendar.MINUTE);
int second = localTime.get(Calendar.SECOND);
// Print the local time
System.out.printf("Local time : %02d:%02d:%02d\n", hour, minute, second);
// Create a calendar object for representing a Germany time zone. Then we
// wet the time of the calendar with the value of the local time
Calendar germanyTime = new GregorianCalendar(TimeZone.getTimeZone("Germany"));
germanyTime.setTimeInMillis(localTime.getTimeInMillis());
hour = germanyTime.get(Calendar.HOUR);
minute = germanyTime.get(Calendar.MINUTE);
second = germanyTime.get(Calendar.SECOND);
// Print the local time in Germany time zone
System.out.printf("Germany time: %02d:%02d:%02dn", hour, minute, second);
}
}
Category Archives: Util Package
How do I set default Locale?
package org.kodejava.util;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.Random;
public class DefaultLocaleExample {
public static void main(String[] args) {
// Use Random class to generate some random number
Random random = new Random();
// We use the system default locale to format a number and a date.
NumberFormat formatter = new DecimalFormat();
Locale locale = Locale.getDefault();
System.out.println("Default Locale = " + locale);
System.out.println("Number = " + formatter.format(random.nextDouble()));
System.out.println("Date = " + new SimpleDateFormat().format(new Date()));
// We change the default locale to Locale.ITALY by setting it through
// the Locale.setDefault() method, and then we format another number
// and date using a new locale. This change will affect all the class
// that aware to the Locale, such as the NumberFormat class.
Locale.setDefault(Locale.ITALY);
NumberFormat newFormatter = new DecimalFormat();
System.out.println("New Locale = " + Locale.getDefault());
System.out.println("Number = " + newFormatter.format(random.nextDouble()));
System.out.println("Date = " + new SimpleDateFormat().format(new Date()));
}
}
The result of the code snippet above are:
Default Locale = en_US
Number = 0.557
Date = 9/26/21, 12:05 PM
New Locale = it_IT
Number = 0,217
Date = 26/09/21, 12:05
How do I remove duplicate element from array?
This example demonstrates you how to remove duplicate elements from an array using the help of java.util.HashSet class.
package org.kodejava.util;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
public class ArrayRemoveDuplicate {
public static void main(String[] args) {
// A string array with duplicate values.
String[] data = {"A", "C", "B", "D", "A", "B", "E", "D", "B", "C"};
System.out.println("Original array : " + Arrays.toString(data));
// Convert a string array into java.util.List because we need a list
// object to create the java.util.Set object.
List<String> list = Arrays.asList(data);
// A set is a collection object that cannot have a duplicate values,
// by converting the array to a set the duplicate value will be removed.
Set<String> set = new HashSet<>(list);
// Convert the java.util.Set back to array using the toArray() method of
// the set object copy the value in the set to the defined array.
String[] result = set.toArray(new String[0]);
System.out.println("Array with no duplicate: " + Arrays.toString(result));
}
}
The result of the code snippet above:
Original array : [A, C, B, D, A, B, E, D, B, C]
Array with no duplicate: [A, B, C, D, E]
How do I convert Array to java.util.Set?
package org.kodejava.util;
import java.util.*;
public class ArrayToSetExample {
public static void main(String[] args) {
Integer[] numbers = {7, 7, 8, 9, 10, 8, 8, 9, 6, 5, 4};
// To convert an array into a java.util.Set firstly we need to convert the
// array into a java.util.List using the Arrays.asList() method. With the
// List object created we can instantiate a new java.util.HashSet and pass
// the list as the constructor parameter.
List<Integer> numberList = Arrays.asList(numbers);
Set<Integer> numberSet = new HashSet<>(numberList);
// Or we can simply combine the line above into single line.
Set<Integer> anotherNumberSet = new HashSet<>(Arrays.asList(numbers));
// Display what we get in the set using iterator.
for (Iterator<Integer> iterator = numberSet.iterator(); iterator.hasNext(); ) {
Integer number = iterator.next();
System.out.print(number + ", ");
}
// Display what we get in the set using for-each.
for (Integer number : anotherNumberSet) {
System.out.print(number + ", ");
}
}
}
How do I use the HashMap class?
This example demonstrate you how to use the HashMap class to store values in a key-value structure. In this example we store a map of error codes with their corresponding description. To store a value into the map we use the put(key, value) method and to get it back we use the get(key) method. And we can also iterate the map using the available key sets of the map.
package org.kodejava.util;
import java.util.HashMap;
import java.util.Map;
public class HashMapDemo {
public static void main(String[] args) {
Map<String, String> errors = new HashMap<>();
// mapping some data in the map
errors.put("404", "Resource not found");
errors.put("403", "Access forbidden");
errors.put("500", "General server error");
// reading data from the map
String errorDescription = errors.get("404");
System.out.println("Error 404: " + errorDescription);
// Iterating the map by the keys
for (String key : errors.keySet()) {
System.out.println("Error " + key + ": " + errors.get(key));
}
}
}
The result of the code snippet above:
Error 404: Resource not found
Error 500: General server error
Error 403: Access forbidden
Error 404: Resource not found