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Java Java Objects (Retired) Meet Objects Creating New Objects

Jiten Mistry
Jiten Mistry
4,698 Points
Posted by Jiten Mistry
Jiten Mistry
4,698 Points

Java error

How would i get pass this error ?

./Example.java:6: error: non-static method getColor() cannot be referenced from a static context System.out.printf("%s", GoKart.getColor()); ^

Example.java 
public class Example {

    public static void main(String[] args) {
        System.out.println("We are going to create a GoKart");
      GoKart goKart = new GoKart("red");
      System.out.printf("%s", GoKart.getColor());
    }
}

1 Answer

James Pamplona
James Pamplona
10,015 Points

You're trying to call the getColor() method on the GoKart class itself. Call the method on the goKart instance (lowercase 'g'). 

System.out.printf("%s", goKart.getColor());
Jiten Mistry
Jiten Mistry
4,698 Points
Jiten Mistry
Jiten Mistry
4,698 Points

Thank you it worked, but could you explain why we use lower case?

James Pamplona
James Pamplona
10,015 Points

Sure. It's about Classes vs objects (also referred to as instances). In Java, and in many other programming languages as well, it's a common convention to name classes beginning with uppercase to help us differentiate them from variables, which typically begin with lowercase . GoKart is the name of the class, the "blueprint," from which any number of concrete instances can be made.

In the second to last line in your code above...

GoKart goKart = new GoKart("red");

...we are creating an instance variable named goKart (though we could call it anything such as myKart if we wanted) which is then a fully functioning, "live," instance of the GoKart class. Then in the last line, we are calling the getColor() method on that instance.

The course on Java Objects should elaborate on this more as you go on, but let me know if you're still having trouble.

Good luck!