Tutorial by Examples: b

A boolean can store one of two values, either true or false boolean foo = true; System.out.println("foo = " + foo); // foo = true boolean bar = false; System.out.println("bar = " + bar); // bar = false boolean notFoo = !foo; System.out.prin...

Server: Start, and wait for incoming connections //Open a listening "ServerSocket" on port 1234. ServerSocket serverSocket = new ServerSocket(1234); while (true) { // Wait for a client connection. // Once a client connected, we get a "Socket" object // that c...

A byte is a 8-bit signed integer. It can store a minimum value of -27 (-128), and a maximum value of 27 - 1 (127) byte example = -36; byte myByte = 96; byte anotherByte = 7; byte addedBytes = (byte) (myByte + anotherByte); // 103 byte subtractedBytes = (byte) (myBytes - anotherByte); // 89 ...

A double is a double-precision 64-bit IEEE 754 floating point number. double example = -7162.37; double myDouble = 974.21; double anotherDouble = 658.7; double addedDoubles = myDouble + anotherDouble; // 315.51 double subtractedDoubles = myDouble - anotherDouble; // 1632.91 double scientif...

Buttons can have a graphic. graphic can be any JavaFX node, like a ProgressBar button.setGraphic(new ProgressBar(-1)); An ImageView button.setGraphic(new ImageView("images/icon.png")); Or even another button button.setGraphic(new Button("Nested button"));

By default, WebView does not implement JavaScript alert dialogs, ie. alert() will do nothing. In order to make you need to firstly enable JavaScript (obviously..), and then set a WebChromeClient to handle requests for alert dialogs from the page: webView.setWebChromeClient(new WebChromeClient() { ...

OptionalDouble, OptionalInt and OptionalLong work like Optional, but are specifically designed to wrap primitive types: OptionalInt presentInt = OptionalInt.of(value); OptionalInt absentInt = OptionalInt.empty(); Because numeric types do have a value, there is no special handling for null. Empt...

Enum can be considered to be syntax sugar for a sealed class that is instantiated only a number of times known at compile-time to define a set of constants. A simple enum to list the different seasons would be declared as follows: public enum Season { WINTER, SPRING, SUMMER, FA...

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...

The Standard Edition of Java comes with some annotations predefined. You do not need to define them by yourself and you can use them immediately. They allow the compiler to enable some fundamental checking of methods, classes and code. @Override This annotation applies to a method and says that th...

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(); ...

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...

// Obtain an instance of JavaScript engine ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("nashorn"); // Define a global variable engine.put("textToPrint", "Data defined in Java."); // Print the global var...

Calling a Java method from native code is a two-step process : obtain a method pointer with the GetMethodID JNI function, using the method name and descriptor ; call one of the Call*Method functions listed here. Java code /*** com.example.jni.JNIJavaCallback.java ***/ package com.example....

Classes implementing Iterable<> interface can be used in for loops. This is actually only syntactic sugar for getting an iterator from the object and using it to get all elements sequentially; it makes code clearer, faster to write end less error-prone. public class UsingIterable { pub...

To create your own Iterable as with any interface you just implement the abstract methods in the interface. For Iterable there is only one which is called iterator(). But its return type Iterator is itself an interface with three abstract methods. You can return an iterator associated with some coll...

WebHistory history = webView.getEngine().getHistory(); The history is basically a list of entries. Each entry represents a visited page and it provides access to relevant page info, such as URL, title, and the date the page was last visited. The list can be obtained by using the getEntries() met...

import static java.awt.BorderLayout.*; import javax.swing.*; import java.awt.BorderLayout; JPanel root = new JPanel(new BorderLayout()); root.add(new JButton("East"), EAST); root.add(new JButton("West"), WEST); root.add(new JButton("North"), NORTH); root.add(...