Does Java support structs?
Java definitively has no structs 🙂 But what you describe here looks like a JavaBean kind of class.
java
“No X11 DISPLAY variable” – what does it mean?
If you’re on the main display, then or if you’re using csh or tcsh before running your app. Actually, I’m surprised it isn’t set automatically. Are you trying to start this application from a non-graphic terminal? If not, have you modified the default .profile, .login, .bashrc or .cshrc? Note that setting the DISPLAY to :0.0 … Read more
Array ArrayList python equivalent
ArrayList in java and list in python are both dynamic arrays. They both have O(1) average indexing time and O(1) average adding an element to the end time. Array in java is not tuple in python. While it is true that you cannot add elements to both data structures. Python tuple does not support assignment, that is you cannot reassign individual elements in a tuple, … Read more
Generic Interface
Here’s one suggestion: Because of type erasure any class will only be able to implement one of these. This eliminates the redundant method at least. It’s not an unreasonable interface that you’re proposing but I’m not 100% sure of what value it adds either. You might just want to use the standard Callable interface. It doesn’t support … Read more
How do I limit the number of decimals printed for a double?
Use a DecimalFormatter: Will give you “0.99”. You can add or subtract 0 on the right side to get more or less decimals. Or use ‘#’ on the right to make the additional digits optional, as in with #.## (0.30) would drop the trailing 0 to become (0.3).
Javac is not found
As far as I can see you have the JRE in your PATH, but not the JDK. From a command prompt try this: Then try javac again – if this works you’ll need to permanently modify your environment variables to have PATH include the JDK too.
Initialize List> in Java
Use or since Java 1.7
How to use java.net.URLConnection to fire and handle HTTP requests
First a disclaimer beforehand: the posted code snippets are all basic examples. You’ll need to handle trivial IOExceptions and RuntimeExceptions like NullPointerException, ArrayIndexOutOfBoundsException and consorts yourself. In case you’re developing for Android instead of Java, note also that since introduction of API level 28, cleartext HTTP requests are disabled by default. You are encouraged to use HttpsURLConnection, but if it is really … Read more
Does the Project Lombok @Data annotation create a constructor of any kind?
A @RequiredArgsConstructor will be generated if no constructor has been defined. The Project Lombok @Data page explains: @Data is like having implicit @Getter, @Setter, @ToString, @EqualsAndHashCode and @RequiredArgsConstructor annotations on the class (except that no constructor will be generated if any explicitly written constructor exists).
What does “?” mean in Java?
someval = (min >= 2) ? 2 : 1; This is called ternary operator, which can be used as if-else. this is equivalent to Follow this tutorial for more info and usage.