How to Fix java.lang.classcastexception in Java?

import java.math.BigDecimal;
public class ClassCastExceptionExample {
    public static void main(String[] args)
    {
        // Creating a BigDecimal object
        Object sampleObject = new BigDecimal(10000000.45);
        System.out.println(sampleObject);
    }
}

import java.math.BigDecimal;
public class Main {
    public static void main(String[] args)
    {
        // Creating a BigDecimal object
        Object sampleObject = new BigDecimal(10000000.45);
      
        // Trying to display the object by casting to String
        // As the object is created as BigDecimal but tried
        // to display by casting to String,
        // ClassCastException is thrown
        System.out.println((String)sampleObject);
    }
}

import java.math.BigDecimal;

public class ClassCastExceptionExample {
    public static void main(String[] args)
    {
        // Creating a BigDecimal object
        Object sampleObject = new BigDecimal(10000000.45);
      
        // We can avoid ClassCastException by this way
        System.out.println(String.valueOf(sampleObject));
    }
}

class Vehicle {
    public Vehicle()
    {
        System.out.println(
            "An example instance of the Vehicle class to proceed for showing ClassCastException");
    }
}

final class Bike extends Vehicle {
    public Bike()
    {
        super();
        System.out.println(
            "An example instance of the Bike class that extends Vehicle as parent class to proceed for showing ClassCastException");
    }
}

public class ClassCastExceptionExample {
    public static void main(String[] args)
    {
        Vehicle vehicle = new Vehicle();
        Bike bike = new Bike();
        Bike bike1 = new Vehicle();
        // Check out for this statement.  Tried to convert
        // parent(vehicle) object to child object(bike).
        // Here compiler error is thrown

        bike = vehicle;
    }
}

// An easier way to understand Downcasting
class Vehicle {
    String vehicleName;

    // Method in parent class
    void displayData()
    {
        System.out.println("From Vehicle class");
    }
}

class Bike extends Vehicle {
    double cost;

    // Overriding the parent class method and we can
    // additionally mention about the child class
    @Override void displayData()
    {
        System.out.println("From bike  class" + cost);
    }
}

public class ClassCastExceptionExample {
    public static void main(String[] args)
    {

        Vehicle vehicle = new Bike();
        vehicle.vehicleName = "BMW";

        // Downcasting Explicitly
        Bike bike = (Bike)vehicle;

        bike.cost = 1000000;
      
        // Though vehiclename is not assigned, it takes BMW
        // as it is
        System.out.println(bike.vehicleName);
        System.out.println(bike.cost);
        bike.displayData();
    }
}

// An easier way to understand Upcasting
class Vehicle {
    String vehicleName;
  
    // Method in parent class
    void displayData()
    {
        System.out.println("From Vehicle class");
    }
}
class Bike extends Vehicle {
  
    double cost;
  
    // Overriding the parent class method and we can
    // additionally mention about the child class
    @Override void displayData()
    {
        System.out.println("From bike  class..." + cost);
    }
}

public class ClassCastExceptionExample {
    public static void main(String[] args)
    {
        // Upcasting
        Vehicle vehicle = new Bike();
      
        vehicle.vehicleName = "Harley-Davidson";
      
        // vehicle.cost //not available as upcasting done
        // but originally Vehicle class dont have cost
        // attribute
        System.out.println(vehicle.vehicleName);
      
        vehicle.displayData(); // Hence here we will get
                               // output as 0.0
    }
}

class Vehicle {
    public Vehicle()
    {
        System.out.println(
            "An example instance of the Vehicle class to proceed for showing ClassCast Exception");
    }
    public String display()
    {
        return "Vehicle class display method";
    }
}

class Bike extends Vehicle {
    public Bike()
    {
        super(); // Vehicle class constructor msg display as
                 // super() is nothing but calling parent
                 // method
        System.out.println(
            "An example instance of the Bike class that extends \nVehicle as parent class to proceed for showing ClassCast Exception");
    }
    public String display()
    {
        return "Bike class display method";
    }
}

public class ClassCastExceptionExample {
    public static void main(String[] args)
    {
        Vehicle vehicle = new Vehicle();
      
        Bike bike = new Bike();
      
        // But we can make bike point to vehicle, i.e.
        // pointing child object to parent object This is an
        // example for upcasting of child object to parent
        // object. It can be done implicitly This facility
        // gives us the flexibility to access the parent
        // class members
        vehicle = bike;
      
        // As upcasted here, vehicle.display() will provide
        // "Bike class display method" as output It has lost
        // its parent properties as now vehicle is nothing
        // but bike only
        System.out.println(
            "After upcasting bike(child) to vehicle(parent).."
            + vehicle.display());
    }
}