$1.$To develop a vehicle class hierarchy in Java to demonstrate the concept of polymorphism.

Step $1$:$-$Declare a super class called vehicle with data elements doors, wheels and seats.

Step $2$:$-$Derive another class called car and invoke a function tostring$0$ to display the variables.

Step $3$:$-$Derive another class calledmotorcycle with same data and method called setseats $0.$

Step $4$:$-$Declare another sub class called Truck with $2$ constructors and finally assign values to variables.

Step $5$:$-$In the main function, create an object for class motorcycle and display all details of sub classes through object.