A default constructor is a constructor in Java that is automatically created by the compiler when a class does not have any constructor defined. This constructor takes no parameters and has an empty body. Its purpose is to initialize the member variables of the class with default values.
For example, consider the following class:
public class MyClass {
int num;
String str;
}
Since this class does not have any constructor defined, the Java compiler automatically creates a default constructor for it. The default constructor would look like this:
public MyClass() {
}
When an object of MyClass is created, the default constructor is called automatically to initialize the member variables num and str to their default values (which are 0 and null, respectively).
It is important to note that if a class has any constructor defined, the compiler does not create a default constructor. In that case, the class only has the constructors that are defined explicitly.
