system.out.println statement outside any method in java

My question is can't we write an output statement outside the main in java? If I enclose it in { } braces then I don't get error, but if I directly write it, I get an error. why so?

public class abc 
{ 
   int a=3; 
   int b=0; 
   System.out.println("this statement gives error"); //Error!! 
   {System.out.println("this works fine");} 
   public static void main(String args[]) {

   System.out.println("main"); 
      abc t=new abc();
   }
} 

I tried writing it in main, it works. Why doesn't it work without a method?

When you enclose it in braces, you are putting it in an initializer block, which runs when the class is instantiated. No statements except variables declarations/initialization may take place outside of methods or initialization blocks in Java.

A Class can only have attributes or methods.

A class is the blueprint from which individual objects are created.

    int a=3;   // attributes
    int b=0;   // attributes
    System.out.println("this statement gives error"); //Error!! 

    {System.out.println("this works fine");}  // init block whenever an object is created.
                                              // since it is inside { }