“Could not resolve matching constructor” error when passing in constructor-arg for child class

Question

I have the following classes:

public abstract class ParentClass
{
    public ParentClass()
    {
        throw new RuntimeException(\"An ID must be specified         


        

Answer 1

If you do not provide a constructor in your child class,the compiler inserts a no-arg constructor and adds the first line as call to super no-arg constructor So your code becomes :-

public class ChildClass extends ParentClass {

        public ChildClass() {
            super();
        }
    }

Obviously, u have thrown a null pointer exception which may be causing the problem.I suggest you to add a constructor and make a call to super constrcutor which takes String argument:-

public class ChildClass extends ParentClass {
        public ChildClass(String id) {
            super(id);
        }

        @Override
        public void doInstanceStuff() {
            // ....
        }
    }

This should solve all your problems...

Note:- If you add a argument constructor,the compiler doesn't not add a default constructor for you.

Now your beans will initialize properly as it will call the string argument constructor. Currently the compiler is providing a default no-arg constrcutor for you which in turn is calling your no arg parent class constructor and is throwing a null pointer exception..