Default class extended by all classes in Java

In Java, by default, do all classes extend the default class?

Example: if I have a simple class, such as:

Class A
{
String a;
}

Does this class extend a class by default?

Solution

java. Lang. object class is a superclass of all classes

You can test:

A a = new A();
if(a instanceof Object){
  System.out.println("Object is superclass of all classes");
}