Which constructor is called first while passing null in the class having overloaded constructor?

Question

Below is the java class having 3 overloaded constructors :

public class Test {

    public Test(Object i){
        System.out.println(\"Object invoked\");
    }
         


        

Answer 1

The answer is: Test(String) is invoked.

Why?

When determining which of a set of overloaded methods will be invoked, the Java compiler will attempt to match the most concrete type. And it will first attempt to match a signature before employing autoboxing. (@arshajii provided a perfect reference into the Java Language Spec on this)

Here, Object is the most abstract class in the type system. String subclasses from Object and is therefore more specific/concrete.

The logic behind this is that if you are overloading a method with a more specific-typed parameter, you're likely wanting to do more with that object (when you subclass, you typically add methods). If method signature determination worked the other way (i.e. the more abstractly-typed signature winning; here, Test(Object)), then none of the more concrete signatures would ever get called.