Subclass toString should call include super.toString(); re-submit these codes.   public class Vehicle {      private String registrationNumber;      private String ownerName;      private double price;      private int yearManufactured;      Vehicle [] myVehicles = new Vehicle[100];          public Vehicle() {          registrationNumber="";          ownerName="";          price=0.0;          yearManufactured=0;      }      public Vehicle(String registrationNumber, String ownerName, double price, int yearManufactured) {          this.registrationNumber=registrationNumber;          this.ownerName=ownerName;          this.price=price;          this.yearManufactured=yearManufactured;      }      public String getRegistrationNumber() {          return registrationNumber;      }      public String getOwnerName() {          return ownerName;      }      public double getPrice() {          return price;      }      public int getYearManufactured() {          return yearManufactured;      }      public void setRegistrationNumber(String registrationNumber) {          this.registrationNumber=registrationNumber;      }      public void setOwnerName(String ownerName) {          this.ownerName=ownerName;      }      public void setPrice(double price) {          this.price=price;      }      public void setYearManufactured(int yearManufactured) {          this.yearManufactured=yearManufactured;      }          public String toString() {          return " Registration number:"+ registrationNumber +"\n Owner Name:"+ownerName+"\n Price:"+      price+"\n year manufactured"+yearManufactured;      }   public static double findMin(Vehicle[] theVehicles)   {      double lowestPrice = Vehicles[0];      for(int i=1; i<price.length;i++){      if(Vehicles[i] < lowestPrice){          lowestPrice = Vehicles[i];          }       }      return lowestPrice;   }     public class Car extends Vehicle{     private int numberOfDoors;       public Car(String registrationNumber, String ownerName, double price, int yearManufactured, int numberOfDoors) {         super(registrationNumber, ownerName, price, yearManufactured);         this.numberOfDoors = numberOfDoors;     }       public int getNumberOfDoors() {         return numberOfDoors;     }       @Override     public String toString() {         return "Car{" +                 "numberOfDoors=" + numberOfDoors +                 '}';     }       public void setNumberOfDoors(int numberOfDoors) {         this.numberOfDoors = numberOfDoors;     } } public class Truck extends Vehicle{     private int numberOfAxles;       public Truck(String registrationNumber, String ownerName, double price, int yearManufactured, int numberOfAxles) {         super(registrationNumber, ownerName, price, yearManufactured);         this.numberOfAxles = numberOfAxles;     }       public int getNumberOfAxles() {         return numberOfAxles;     }       public void setNumberOfAxles(int numberOfAxles) {         this.numberOfAxles = numberOfAxles;     }       @Override     public String toString() {         return "Truck{" +                 "numberOfAxles=" + numberOfAxles +                 '}';     } }