Tutorial by Examples: f

Often one want to show the result of a command executed by root to other users. The tee command allows easily to write a file with user perms from a command running as root: su -c ifconfig | tee ~/results-of-ifconfig.txt Only ifconfig runs as root.

For null check in method Object nullableObject = methodReturnObject(); if (Objects.isNull(nullableObject)) { return; } For not null check in method Object nullableObject = methodReturnObject(); if (Objects.nonNull(nullableObject)) { return; }

In the old fashion way for collection null check List<Object> someObjects = methodGetList(); for (Object obj : someObjects) { if (obj == null) { continue; } doSomething(obj); } With the Objects.nonNull method and Java8 Stream API, we can do the above in this way: ...

Consider this example: public class ThreadTest implements Runnable { private boolean stop = false; public void run() { long counter = 0; while (!stop) { counter = counter + 1; } System.out.println("Counted " + counter);...

Suppose you have a long list of elements and you are only interested in every other element of the list. Perhaps you only want to examine the first or last elements, or a specific range of entries in your list. Python has strong indexing built-in capabilities. Here are some examples of how to achie...

You can close a notification by using the .close() method. let notification = new Notification(title, options); // do some work, then close the notification notification.close() You can utilize the setTimeout function to auto-close the notification sometime in the future. let notification = n...

The Notification API specifications support 2 events that can be fired by a Notification. The click event. This event will run when you click on the notification body (excluding the closing X and the Notifications configuration button). Example: notification.onclick = function(event) { ...

import java.awt.EventQueue; import java.awt.GridLayout; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.awt.event.WindowListener; import java.util.ArrayList; import java.util.List; import javax.swing.JFrame; import javax.swing.JTextArea; import javax.sw...

Create a font extension using the IDE. See the iReport or Jaspersoft Studio documentation for details. The font extension can also be created manually. What are font extensions? Using a textElement you can specify a font (if not specified default font SansSerif is used) <textElement> &...

The NotifyPropertyChangedBaseclass below defines a generic Set method that can be called from any derived type. public class NotifyPropertyChangedBase : INotifyPropertyChanged { protected void RaisePropertyChanged([CallerMemberName] string propertyName = null) => PropertyChanged?.Invo...

Consider the following partial example: import com.example.somelib.*; import com.acme.otherlib.*; public class Test { private Context x = new Context(); // from com.example.somelib ... } Suppose that when when you first developed the code against version 1.0 of somelib and versi...

Suppose that we have the following text file: jekyll_hyde.txt How do we convert it to a PDF that looks like this: When using iText 5, we'd use the following code: public void createPdf(String dest) throws DocumentException, IOException { Document document = new Document(); PdfWriter....

Suppose that you have the following text file: jekyll_hyde.txt How do we convert it to a PDF that looks like this: When using iText 7, we'd need the following code: public void createPdf(String dest) throws IOException { PdfDocument pdf = new PdfDocument(new PdfWriter(dest)); Document...

There are two main platforms in VR, one is mobile platform, like Google Cardboard, Samsung GearVR, the other is PC platform, like HTC Vive, Oculus, PS VR... Unity officially supports the Oculus Rift, Google Carboard, Steam VR, Playstation VR, Gear VR, and the Microsoft Hololens. Most platforms hav...

Suppose that we have the following text file: jekyll_hyde.txt How do we convert it to a PDF that looks like this: When using iText 5, you'd need code like this: public void createPdf(String dest) throws DocumentException, IOException { Document document = new Document(); PdfWriter wr...

Suppose that you have the following text file: jekyll_hyde.txt How do we convert it to a PDF that looks like this: When using iText 7, you'd need code like this: public void createPdf(String dest) throws IOException { PdfDocument pdf = new PdfDocument(new PdfWriter(dest)); Document do...

Suppose that we have the following text file: jekyll_hyde.txt How do we convert it to a PDF that looks like this: Note the blue border that is added to the titles, and the page number at the bottom of each page. In iText 5, these elements are added using page events: class MyPageEvents extends ...

Suppose that you have the following text file: jekyll_hyde.txt How do we convert it to a PDF that looks like this: Note the page numbers at the bottom of each page. These are added using an IEventHandler implementation: protected class Footer implements IEventHandler { @Override pub...

Suppose that you have the following text file: jekyll_hyde.txt How do we convert it to a PDF that looks like this: Note that this is very similar to what we had before, but the border of the titles now has rounded corners. We created a custom ParagraphRenderer to achieve this, and we created a T...

Executable JAR files are the simplest way to assemble Java code into a single file that can be executed. *(Editorial Note: Creation of JAR files should be covered by a separate Topic.) * Assuming that you have an executable JAR file with pathname <jar-path>, you should be able to run it as f...