调试记录：The public type <<classname>> must be defined in its own file

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“The public type <<classname>> must be defined in its own file” error in Eclipse [duplicate]

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This question already has an answer here:

• Java compiler error: “public type .. must be defined in its own file”? 4 answers

I have written the following code:

package staticshow;

public class StaticDemo {
  static int a = 3;
  static int b = 4;

  static {
    System.out.println("Voila! Static block put into action");
  }

  static void show() {
    System.out.println("a= " + a);
    System.out.println("b= " + b);
  }
}

public class StaticDemoShow {
  public static void main() {
    StaticDemo.show();
  }
}

I am getting the error message:

The public type StaticDemo must be defined in its own file

error in the very first line public class StaticDemo {. Why is it happening and how can I resolve it? Note that my project name is StaticDemoShow, package name is staticshow and class names are as given in the code.

EDIT- After making just one class public or both the classes default, I am getting the error "Selection does not contain a main type". Now what should I do?

java eclipse

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edited Nov 6 '13 at 14:38

asked Nov 6 '13 at 14:29 Mistu4u 1,31751948

marked as duplicate by Holger, Dennis Meng, Raedwald, David L, Jarrod Roberson Nov 6 '13 at 22:32

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

Is your class file named StaticDemo? – Vaughan Hilts Nov 6 '13 at 14:30 

@VaughanHilts, No. My project name is "StaticDemoShow". – Mistu4u Nov 6 '13 at 14:34

2

No need to downvote IMHO. Every beginner will stumble across this. @VaughanHilts It seems both are in the same file. – Axel Nov 6 '13 at 14:34

duplicate of Java compiler error: "public type .. must be defined in its own file" and Public class must be defined in its own file and a lot more I guess… – Holger Nov 6 '13 at 19:14 

just in case you need to rightfully have mulitple types in one file, you may get here and look for another answer and motivation provided here: stackoverflow.com/questions/32012525/… – Andreas Dietrich Aug 14 '15 at 14:33 

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8 Answers

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We cant have two public classes in one file. The JVM cannot understand, in one file we must write one public class only. public class StaticDemo { static int a = 3; static int b = 4; static { System.out.println("Voila! Static block put into action"); } static void show() { System.out.println("a= " + a); System.out.println("b= " + b); } } class StaticDemoShow { public static void main() { StaticDemo.show(); } } shareimprove this answer