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How should I unit test the main method of a JavaFX program?

Right now, I'm considering incorporating 100% code coverage into my project. However, I'm having trouble unit testing the main entry point of my code:
public static void main(String[] args) {
launch(args);
}
This method is difficult to test because it launches an entirely new JavaFX program in the background. In addition to this behavior, a JavaFX program cannot be started more than once. Moreover, the documentation for javafx.application.Application explictly states that, "A JavaFX Application should not attempt to use JavaFX after the FX toolkit has terminated or from a ShutdownHook, that is, after the stop() method returns or System.exit(int) is called."
I am encountering this project because I'm also working with TestFX, a library that helps with clean testing for JavaFX. However, this library does not offer support for the testing of the main method, and as a result I have to write a workaround. There is a possibility of the developers of TestFX knowing about a possible workaround for this problem, for each and every unit tested method, a new instance of an Application is started. Perhaps there could be a way to completely shutdown and reset all variables of a JavaFX program.
To be fair, this method is not that significant to test, however it would be pleasant to have 100% code coverage. It would be entirely reasonable to not test this method as well. The full class can be found below:
package com.meti.app;
import javafx.application.Application;
import javafx.stage.Stage;
/**
* #author SirMathhman
* #version 0.0.0
* #since 4/5/2019
*/ //Main MUST remain public in order for JavaFX Application to start.
public class Main extends Application {
static InfinityImpl implementation = new Infinity();
static Main instance;
#Override
public void start(Stage primaryStage) {
instance = this;
implementation.start(primaryStage);
}
#Override
public void stop() {
implementation.stop();
instance = null;
}
public static void main(String[] args) {
launch(args);
}
}
The static variables above are irrelevant to the aforementioned question and are used for testing purposes in another class which ensures that the delegation works correctly. The application delegates most of the operations to a delegate class which makes the code easier to test.
Moreover, IntelliJ doesn't allow methods to be excluded during code testing.
If you have any other questions, please let me know. Thank you!
Some additional reading:
How to call launch() more than once in java
https://github.com/TestFX/TestFX/blob/master/subprojects/testfx-core/src/main/java/org/testfx/api/FxToolkit.java

Eclipse not having run as java applet application

I setup my eclipse for PROCESSING perfectely..
I am using Eclipse Oxygen and installed PROCESSING 3.3.6
i am trying to run processing program in eclipse and there is no option is run as Applet
My code is below :
package processing01;
import processing.core.PApplet;
public class Processing01 extends PApplet{
public static void main(String[] args) {
PApplet.main("Processing01");
}
public void settings(){
size(300,300);
}
public void setup(){
fill(120,50,240);
}
public void draw(){
ellipse(width/2,height/2,second(),second());
}
}

Processing 3 no longer supports running as an applet. From the Processing 3 change list:
Applet is gone — Java's java.awt.Applet is no longer the base class used by PApplet, so any sketches that make use of Applet-specific methods (or assume that a PApplet is a Java AWT Component object) will need to be rewritten.
The PApplet class no longer extends the Applet class, which means you can't treat Processing sketches as a component anymore, and you can't run them as an applet. You can only run them as an application.
Applets are dead, and shouldn't be used anyway.

Because having package the code would be
//replace
PApplet.main("Processing01");
//with
PApplet.main("processing01.Processing01");

debug in javafx without a main method

I have just started using Javafx and I have enjoyed it so far. However I wanted to do some de-bugging with it, and I get this error.
Error: Main method not found in class fx.MyProgram, please define the main method as:
public static void main(String[] args)
If I go ahead and add a main method... the body is empty because all the magic happens from button clicks from the View. Do I need to change some configurations? Running the app works fine, but de-bugging doesn't work.

nvm I figured it out myself. For anyone else who runs into this...
public static void main(String [] args){
Application.launch(args);
}

how to print "hello world" without MAIN method and also without using STATIC and FINAL key word in java

class a {
public static void main(String args[]) {
}
}
i want to print "hello world" without touch or use above code and also without use of static and final keyword......

What are the different ways to initiate code execution.
Use public static void main(String args[]) { ... }
Use your static class initializer static { ... }. Problem: You need to get the class to load first. Solution: attempt to start the main method, but that means you need to have at least an empty main. However - OP states we cannot use 'static'.
Use an instance initializer { ... }. Problem: How do you instantiate an instance. Solution: initialize a static field with a class instance. However - OP states we cannot use static fields.
So what is left. I assume that we can use the empty main posted by the OP. From there on we build up a 4th solution:
public enum Play {
PLAY;
{ System.out.println("Hello World!"); }
public static void main(String args[]) { }
}
This should fulfill the conditions:
we do not modify the static main method, although we need the empty body just to get the class loaded.
we do not use a static initializer, we use an instance initializer instead.
to instantiate, and get the instance initializer started, we use an enum. Enum's start the initializer for each instance, meaning for each of the enum constants.
Also note the output when you try to execute a class without a main:
$ java -classpath . Play
Error: Main method not found in class Play, please define the main method as:
public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application
So that leaves us also the clue that we potentially can use javafx.application.Application. I did not investigate this trail any further.

You can create a JavaFX application, which is usually for displaying a GUI, and use it to output hello, world to the console and immediately shut the JavaFX GUI system down. JavaFX applications are executed by a special launch path in the java launcher. JavaFX applications do not need a main, static and final keywords.
The following snippet is just for demo purposes, I wouldn't recommend writing a JavaFX application unless you actually wish to display a GUI.
import javafx.application.Application;
import javafx.application.Platform;
import javafx.stage.Stage;
public class PlayApp extends Application {
#Override
public void start(Stage stage) {
System.out.println("hello, world");
Platform.exit();
}
}
// Totally useless code from the original question
// goes below the real app code and is just ignored
// and never used when the application runs.
class a {
public static void main(String args[]) {
}
}
You need to use Oracle Java 8+ to compile and execute the JavaFX application as below:
javac PlayApp.java
java PlayApp
The a class is in the PlayApp.java file only to meet the original poster's requirement from a comment:
it means the above code is fixed, you can't modify the above code but yes u can write anything to print "hello world" above or belove this code
Really, if you are writing a console application, just use a standard app format (with a static main method) instead:
class HelloWorldApp {
public static void main(String[] args) {
System.out.println("Hello World!"); // Display the string.
}
}
Unrelated advice on asking questions
In future, if you post such questions, I suggest that you also supply the reason for the question and why the bizarre constraints are placed on solutions. Also, address concerns such as WorldEnder's first comment on your question: "is this a code challenge? If not.. why?"

You can't just print "hello world" without MAIN method and also without using STATIC and FINAL key word in java because the main method is a function required you don't have to apply any rocket science in that thing if u are using intelliJ IDEA or any other IDE anyways this is the code
public class Basics_Of_Java {
public static void main(String[] args) {
System.out.println("Hello world");
basics of java in 1st line is the name of the java file you may have another name.

Main method not found even if I've declared it

I want to create a simple java class, with a main method, but when I compile my code, I get this error message :
Error: Main method not found in class errors.TestErrors, please define
the main method as: public static void main(String[] args)
This is the source code :
package errors;
public class TestErrors {
public static void main(String[] args){
System.out.println("hello");
}
}
Why I'm seeing this error, as you can notice I've alreader declared the main method !

As said in my comments, looks like you've declared a String class among your own classes. To prove this, I've created a basic example:
class String {
}
public class CarelessMain {
public static void main(String[] args) {
System.out.println("won't get printed");
}
public static void main(java.lang.String[] args) {
System.out.println("worked");
}
}
If you execute this code, it will print "worked" in the console. If you comment the second main method, the application will throw an error with this message (similar for your environment):
Error: Main method not found in class edu.home.poc.component.CarelessMain, please define the main method as:
public static void main(String[] args)

This usually happens if ur complete project isnotconfigured correctly
or one of your class in project has still some errors
in such cases IDE will prompt stating the same that project contains some error
and you still proceed (ie run your class)
as project has some bugs new classes will not be created and IDE will run
the class which was available previously
to make sure this is ur case u can add new class in your project and try to run it and if ur getting no such class exist then there its is a perfect evidence

Just check your java file, it has not been saved. Please save all java files before compiling.

If the answers above are not working for you: make sure "main" is not capitalized in your method definition.
OK:
public static void main(String[] args)
ERROR:
public static void Main(String[] args)
Though the error message makes the required syntax for the main method clear, incorrect caps can be hard to spot. It took me ~30 minutes of troubleshooting to find this typo today. This was clearly not an issue for the OP, but is another easy/likely way to produce the same error message, and this answer may help other users.

I had this issue just now. This error came up because the JRE file that i switched out didn't had the full library. After I corrected/added the right JRE system library the problem went away.

Right click on the class name (which you are trying to run)->Run As->Run Configurations->Under Main Class Tab
Write your main class name and hit on Run.

Try commenting the first line.
//package errors;