Tutorial by Examples: g

An enum can contain a method, just like any class. To see how this works, we'll declare an enum like this: public enum Direction { NORTH, SOUTH, EAST, WEST; } Let's have a method that returns the enum in the opposite direction: public enum Direction { NORTH, SOUTH, EAST, WEST; ...

String getText(String url) throws IOException { HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection(); //add headers to the connection, or check the status if desired.. // handle error response code it occurs int responseCode = conn.getResponseCod...

One use of SharedPreferences is to implement a "Settings" screen in your app, where the user can set their preferences / options. Like this: A PreferenceScreen saves user preferences in SharedPreferences. To create a PreferenceScreen, you need a few things: An XML file to define the av...

Scanner scanner = new Scanner(System.in); //Scanner obj to read System input String inputTaken = new String(); while (true) { String input = scanner.nextLine(); // reading one line of input if (input.matches("\\s+")) // if it matches spaces/tabs, stop reading b...

Scanner scanner = null; try { scanner = new Scanner(new File("Names.txt")); while (scanner.hasNext()) { System.out.println(scanner.nextLine()); } } catch (Exception e) { System.err.println("Exception occurred!"); } finally { if (scanner != nul...

Sometimes the same functionality has to be written for different kinds of inputs. At that time, one can use the same method name with a different set of parameters. Each different set of parameters is known as a method signature. As seen per the example, a single method can have multiple signatures....

Here we have a class Counter with methods countNumbers() and hasNumbers(). public class Counter { /* To count the numbers in the input */ public static int countNumbers(String input) { int count = 0; for (char letter : input.toCharArray()) { if (Character....

Paginations in JavaFX use a callback to get the pages used in the animation. Pagination p = new Pagination(); p.setPageFactory(param -> new Button(param.toString())); This creates an infinite list of buttons numbed 0.. since the zero arg constructor creates an infinite pagination. setPageFac...

ArrayList<String> images = new ArrayList<>(); images.add("some\\cool\\image"); images.add("some\\other\\cool\\image"); images.add("some\\cooler\\image"); Pagination p = new Pagination(3); p.setPageFactory(n -> new ImageView(images.get(n))); Note...

The Collections class offers two standard static methods to sort a list: sort(List<T> list) applicable to lists where T extends Comparable<? super T>, and sort(List<T> list, Comparator<? super T> c) applicable to lists of any type. Applying the former requires amending...

In your build.gradle file of main module(app), define your minimum and target version number. android { //the version of sdk source used to compile your project compileSdkVersion 23 defaultConfig { //the minimum sdk version required by device to run your app minSd...

Date date = new Date(); System.out.println(date); // Thu Feb 25 05:03:59 IST 2016 Here this Date object contains the current date and time when this object was created. Calendar calendar = Calendar.getInstance(); calendar.set(90, Calendar.DECEMBER, 11); Date myBirthDate = calendar.getTime(); ...

Calendar, Date, and LocalDate Java SE 8 before, after, compareTo and equals methods //Use of Calendar and Date objects final Date today = new Date(); final Calendar calendar = Calendar.getInstance(); calendar.set(1990, Calendar.NOVEMBER, 1, 0, 0, 0); Date birthdate = calendar.getTime(); ...

format() from SimpleDateFormat class helps to convert a Date object into certain format String object by using the supplied pattern string. Date today = new Date(); SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MMM-yy"); //pattern is specified here System.out.println(date...

parse() from SimpleDateFormat class helps to convert a String pattern into a Date object. DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.SHORT, Locale.US); String dateStr = "02/25/2016"; // input String Date date = dateFormat.parse(dateStr); System.out.println(date.getYe...

Calendar objects can be created by using getInstance() or by using the constructor GregorianCalendar. It's important to notice that months in Calendar are zero based, which means that JANUARY is represented by an int value 0. In order to provide a better code, always use Calendar constants, such as...

add() and roll() can be used to increase/decrease Calendar fields. Calendar calendar = new GregorianCalendar(2016, Calendar.MARCH, 31); // 31 March 2016 The add() method affects all fields, and behaves effectively if one were to add or subtract actual dates from the calendar calendar.add(Calend...

When desired XML format differs from Java object model, an XmlAdapter implementation can be used to transform model object into xml-format object and vice versa. This example demonstrates how to put a field's value into an attribute of an element with field's name. public class XmlAdapterExample { ...

"External" Storage is another type of storage that we can use to save files to the user's device. It has some key differences from "Internal" Storage, namely: It is not always available. In the case of a removable medium (SD card), the user can simply remove the storage. It i...

The getClass() method can be used to find the runtime class type of an object. See the example below: public class User { private long userID; private String name; public User(long userID, String name) { this.userID = userID; this.name = name; } } pu...