**Considering the example of Java class hierarchy discussed in class, write the following programs: Ram.java, Truck.java, LandVehicle.java and Vehicle.java.**
Requirements
* Your Java class names must follow the names specified above. Note that they are case sensitive. See our template below.
* Class Ram contains a main method, which is the entrance of the program.
* Each class has to have its no-arg constructor. The behavior of the constructor is to print out a String. For example, class Truck's constructor will print "Truck's no-arg constructor is invoked.".
* Make sure your programs compile and submit your programs by following the submission instruction.
Program Template
```Java
public class Ram extends Truck {
public static void main(String[] args) {
// your implementation
}
public Ram() {
// your implementation
}
}
public class Truck extends LandVehicle {
public Truck() {
// your implementation
}
public Truck(String s) {
// your implementation
}
}
public class LandVehicle extends Vehicle {
public LandVehicle() {
// your implementation
}
}
public class Vehicle {
public Vehicle() {
// your implementation
}
}
```
