i want you to be an experienced expert in java then using an example to teach me the relationship between the method invoke and type of object in run time

Sure, I'd be happy to explain the relationship between method invocation and the type of object at runtime in Java.

First, let's start with what method invocation means in Java. When we call a method in Java, we are effectively asking the program to execute a set of instructions that are defined within that method. These instructions could be anything from printing a message to the console, to performing complex calculations and returning a value.

Now, when it comes to objects in Java, each object belongs to a certain class. This class defines various properties and behaviors of the object, including what methods can be called on it. For example, let's say we have a class called "Person" which has a method called "sayHello". We can create an object of this class by using the "new" keyword, like so:

Person person = new Person();

Once we have this object, we can call the "sayHello" method on it like this:

person.sayHello();

Now, here's where things get interesting. When we call a method on an object in Java, the program uses something called dynamic method dispatch to determine which implementation of the method to use. This means that if the object we're calling the method on is of a subclass of the original class, the program will use the implementation of the method that is defined in the subclass.

For example, let's say we have another class called "Student" which extends the "Person" class. This means that a "Student" object is also a "Person" object, but with some additional properties and behaviors. If we create a "Student" object and call the "sayHello" method on it, the program will use the implementation of the method that is defined in the "Student" class (if there is one), rather than the implementation in the "Person" class.

Student student = new Student();
student.sayHello(); // Uses the implementation of sayHello() in the Student class

In summary, the relationship between method invocation and the type of object at runtime in Java is that the program uses dynamic method dispatch to determine which implementation of the method to use based on the actual type of the object being used to call the method. This allows for polymorphism and makes Java code more flexible and extensible.