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

Question

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......

Answer 1

What are the different ways to initiate code execution.

1. Use public static void main(String args[]) { ... }
2. 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'.
3. 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:

1. we do not modify the static main method, although we need the empty body just to get the class loaded.
2. we do not use a static initializer, we use an instance initializer instead.
3. 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.

Answer 2

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?"

Answer 3

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.