CODEWITHSUNDEEP
java
Diana
Diana

Reputation: 1437

Static variable declaration is superclass - Java

I have the following program:

class Vehicle{  
  static int speed=50;  
  Vehicle(){
      this.speed=speed;
  }
}  


class Bike4 extends Vehicle{  
  int speed=100;  

  void display(){  
   System.out.println(Vehicle.speed);//will print speed of Vehicle now  
  }  
  public static void main(String args[]){  
   Bike4 b=new Bike4();  
   b.display();  
   }  
}

Supposing I don't want to use the keyword "super" and I simply call the function "Vehicle.speed" why do I have to change the type of the variable speed in the superclass to static? What would happen if I run the program without using the static keyword? (again, supposing it compiles)

Upvotes: 1

Views: 60

Answers (1)

spudone
spudone

Reputation: 1277

Because you're defining a different speed for Bike4 as opposed to the parent Vehicle, it looks like you want to change the derived value. A static variable won't work because it belongs to the class, not the instance. I think you want something like this instead:

public class Vehicle{  
    protected int speed;  
    Vehicle(int speed) {
        this.speed=speed;
    }
}  


public class Bike4 extends Vehicle {
    public Bike4(int speed) {
        super(speed);
    }

    void display() {  
        System.out.println(speed);
    }
    public static void main(String args[]) {  
        Bike4 b=new Bike4(100);  
        b.display();  
    }  
}

Upvotes: 1

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