Why do we still need to implement 'noArgsConstructor' if Java gives a non-parameterized constructor by default?

In Spring boot if we are creating a POJO class and we end up creating only a parameterized constructor and not any default constructor then Java will throw errors, why does this happen if Java provides a non-parameterized constructor by default why do I still have to implement it manually?

I tried not creating a non-parameterized constructor for a POJO and it threw an error when I created an object of the POJO class in another class.

In Java, if you don't provide any constructor explicitly in your class, Java provides a default constructor. However, there's an exception to this rule. If you define any constructor explicitly in your class, Java won't provide a default constructor for you.

public class Employee{
    // No constructor defined explicitly

    // Other class members and methods
}

In this case, since no constructor is explicitly defined, Java will provide a default constructor for the Employee class.

However, if you define any constructor in your class, then Java won't provide a default constructor. For example:

public class Employee{
    String name;
    public Employee(String name) {
        // Constructor with parameter
    }

    // Other class members and methods
}

In this case, since a constructor is explicitly defined (Employee(String x)), Java won't provide a default constructor for Employee. If you need a default constructor along with your parameterized constructor, you'll need to define it explicitly:

public class Employee{
    String x
    public Employee(String name) {
        // Constructor with parameter
    }

    public Employee() {
        // Default constructor
    }

    // Other class members and methods
}

Now, the Employee has both a parameterized constructor and a default constructor.