Does every program in Java require a class?

后端 未结 6 1173
臣服心动
臣服心动 2020-12-16 02:19

Every Java program requires the presence of at least one class.

Is the above statement always true ?

相关标签:
6条回答
  • 2020-12-16 02:55

    From the JVM's point of view; yes. From a programmers view point, it can be a Class or an Enum.

    public enum AAA {
    
        AAA;
    
        public static void main(final String[] args) {
            System.out.println("H");
        }
    
    }
    

    EDIT: Even if you have a class with empty main method, there are a lot of core classes which work behind the scene to just run the "empty" class of yours. A list of those classes (around 200 from the java.* package) can be viewed by setting the -verbose:class JVM parameter.

    0 讨论(0)
  • 2020-12-16 02:56

    Yes. In Java you always need one class with the function main to have the JRE run it.

    0 讨论(0)
  • 2020-12-16 02:58

    yes , you need minimum one class.

    0 讨论(0)
  • 2020-12-16 03:00

    Yes, you need at least one class to have a program, but no, you do not need any methods (contrary to some other answers).

    The reason you need a class is because in Java, all code is inside classes. So to have any code, you need a class. However, code doesn't necessarily need to be in a method. It can also be in initializers. So, here is a complete Java program with no methods:

    class LookMaNoMethods {
        static {
            System.out.println("Hello, world!");
            System.exit(0);
        }
    }
    

    And that gives...

    $ javac LookMaNoMethods.java 
    $ java LookMaNoMethods 
    Hello, world!
    $ 
    

    EDIT : From Java 7 the above code with just static block and no main method does not produce any output. Main method is now compulsory. The code with no main method compiles successfully though.

    0 讨论(0)
  • 2020-12-16 03:01

    JAVA required at least one class in a program because at the time of execution of Java programs we needed to provide the name of a class which contains the main () method.
    so, it is compulsory to provide at least one class name to Java programs. ex--->`

    class Test 
    { 
    public static void main(String [] args)
    { 
    System.out.println("Hello World");
    }
    }
    

    so, javac _____ ("Here we have to give the name of java program in which we save")

    java ______ ("Provide the name of a class which contain the main() method")

    -----> according to our program

    javac Hello (here I save the program name by Hello.java)

    java Test (because Test class contains main() method)

    Thank You

    0 讨论(0)
  • 2020-12-16 03:03

    A program requires an entry point. An entry point has to be a method. In Java, every method must be contained in a class.

    That would imply that every program must have a at least one class.

    0 讨论(0)
提交回复
热议问题