Exception in thread “main” java.lang.NoSuchMethodError: main // What is wrong?

Question

I have the following simple code :

public class Date
{
 byte day;
 byte month;
 short year;
}
 class DateUse{
  public static void main(String[] args){
   Date date = new Date();
   date.day = 15;
  System.out.println(date.day);
  }
}

I am using Linux terminal to compile my .java code :

javac Date.java

In Windows environment any IDE would compile without any error ,why it is giving me errors in Linux ?

Thank u in advance.

Answer 1

It sounds like you tried to run Date instead of DateUse:

$ javac Date.java

$ java Date
Exception in thread "main" java.lang.NoSuchMethodError: main

$ java DateUse
15

Answer 2

Make DateUse a public class, and make it before the Date class.

Save the file as DateUse.java and compile it with

javac DateUse.java

The DateUse class contains the main method, not Date.

Answer 3

Your main method needs to be in the Date class as your file name represents the class name. Your code should be as follows:

public class Date{
     public byte day;
     public byte month;
     public short year;

     public static void main(String[] args){

       Date date = new Date();
       date.day = 15;
       System.out.println(date.day); 
     }

}