The ‘friend’ concept is useful in Java, for example, to separate an API from its implementation. It is common for implementation classes to need access to API class internals but these should not be exposed to API clients. This can be achieved using the ‘Friend Accessor’ pattern as detailed below: The class exposed through the … Read more
If you look at the JarFile API you’ll see that it’s a subclass of the ZipFile class. The jar-specific classes mostly just add jar-specific functionality, like direct support for manifest file attributes and so on. It’s OOP “in action”; since jar files are zip files, the jar classes can use zip functionality and provide additional utility.
One extra thing I can think of: Instance variables are given default values, i.e., null if it’s an object reference, and 0 if it’s an int. Local variables don’t get default values, and therefore need to be explicitly initialized (and the compiler usually complains if you fail to do this).
What is the main difference between Jetty and Netty? Netty is part of Jboss, but is it the default web server container? Does Netty support Servlets 3.0?
The problem is the semicolon after the if. The grammar is if ( condition ) expression-or-block { else expression-or-block } Since ; is an empty expression, this works for an if clause and nothing happens in the then clause – in your case syntactically there is no else clause, since your if statement statements ends … Read more
Debug your XML file. Either there is space or added extra or fewer tags. For better understanding build the project through the command line. Windows: gradlew build In my case, AndroidManifest.xml has a blank space at the very first line
There is no specialized image component provided in Swing (which is sad in my opinion). So, there are a few options: As @Reimeus said: Use a JLabel with an icon. Create in the window builder a JPanel, that will represent the location of the image. Then add your own custom image component to the JPanel … Read more
Basically, you create a Function interface: and then pass in an anonymous subclass to your method. Your method could either apply the function to each element in-place: or create a new List (basically creating a mapping from the input list to the output list): Which one is preferable depends on your use case. If your … Read more
Typically for local variables I initialize them as late as I can. It’s rare that I need a “dummy” value. However, if you do, you can use any value you like – it won’t make any difference, if you’re sure you’re going to assign a value before reading it. If you want the char equivalent … Read more
Well you probably want array_name.length for getting the count of the rows and array_name[0].length for the columns. That is, if you defined your array like so: