When does the compiler supply a default constructor for a class?

In Java, a default constructor is provided by the compiler under certain circumstances. The compiler automatically supplies a default constructor for a class under the following conditions:

1. No Constructors Defined: If you haven’t defined any constructor for your class, the compiler will provide a default constructor. This is true even if you have other methods or fields in your class.

   Example:

   java

   public class MyClass {
// No explicit constructor defined
}


   The compiler will generate a default constructor equivalent to:

   java

   public class MyClass {
public MyClass() {
// Default constructor code
}
}

2. No Explicit Call to Superclass Constructor: If your class extends another class, and you haven’t explicitly called a superclass constructor using super(...), and the superclass has a no-argument constructor, then the compiler will automatically provide a default constructor for your subclass.

   Example:

   java

   public class MySubclass extends MySuperclass {
// No explicit constructor defined, and no call to super(...) constructor
}


   The compiler will generate a default constructor equivalent to:

   java

   public class MySubclass extends MySuperclass {
public MySubclass() {
super(); // Implicit call to superclass's no-argument constructor
// Default constructor code
}
}


It’s important to note that if you define any constructor (with or without arguments) explicitly in your class, the compiler won’t generate the default constructor. If you define a parameterized constructor and still want the default constructor, you’ll need to explicitly define it in your class.