[Q?]I am puzzled by a small test on constructor

Question

puzzled by a small test on constructor
the main is the same programme, can anybody tell me why i must pre-decalre the x1 outside the public lee1(),
otherwise the class lee2 cannot compile?
I am still in the basic level of OOM. I guess this is because of encapsulation, but not very afirm or clear.
Wrong Coding
public class lee1
     public lee1()
          int x1;
          x1 = 4;
Right Coding
public class lee1
     int x1;
     public lee1()
          x1 = 4;
Same Main
====================
public class lee2
     public static void main (String args[])
          //declare an object to call components in lee1.java
          lee1 abc = new lee1();
          // retrive variable using inheritance method
          System.out.println(abc.x1);
Why prohibit me declare x1 with public visibility as this
public class lee1
     public lee1()
          public     int x1;
          x1 = 4;
}

Answer 1

In main(), you call the lee1() constructor:
public class lee1
     public lee1()
          int x1;
          x1 = 4;
}with this line:
lee1 abc = new lee1();
After the constructor finishes executing x1 no longer exists. x1 is a local variable, and when the constructor ends it goes out of existence. Then, you do this:
System.out.println(abc.x1);
That line says, grab abc.x1 and display it. However, when you write:
abc.x1
you are saying get the member variable named x1 from the object abc. However, you didn't declare any member variables in your class, so abc doesn't have any member variables and certainly not one named x1.
In this class:
public class lee1
     int x1;
     public lee1()
          x1 = 4;
}you declare the member variable x1. Then, in this line:
lee1 abc = new lee1();
you are telling java to create an object called abc and to use the constructor lee1() to create the object. In turn, the constructor lee1() assigns 4 to the member variable x1. Therefore, when you do this:
System.out.println(abc.x1);
abc.x1 instructs java to grab the member variable x1 from the object abc and display it.