can a class extend itself in java?

by

No, a class cannot extend itself in java.
Example

public class Main extends Main
{
    String name = "Jai";
    int rollNo = 11;
    void show(){
        System.out.println(name);
        System.out.println(rollNo);
    }
    public static void main(String[] args)
    {
        Main object = new Main();
        object.show();
    }
}

Output

Main.java:8: error: cyclic inheritance involving Main
public class Main extends Main
       ^
1 error

Java interview questions on Inheritance