Is there a reason for static methods?

Question

I can't really seem to understand static methods. I read many articles on it and also have looked at it in textbooks and the Java docs. I know that you can use static methods to access static variables. Is there really any other reason for class methods other than to get a static variable? If there is another reason can I sort of maybe get an explanation of why? I made this thread also because I haven't found anything in SOF about this.

Here is an example code:

public class Bicycle {

    private int cadence;
    private int gear;
    private int speed;

    private int id;

    private static int numberOfBicycles = 0;


    public Bicycle(int startCadence,
                   int startSpeed,
                   int startGear){
        gear = startGear;
        cadence = startCadence;
        speed = startSpeed;

        id = ++numberOfBicycles;
    }

    public int getID() {
        return id;
    }

    public static int getNumberOfBicycles() {
        return numberOfBicycles;
    }

    public int getCadence(){
        return cadence;
    }

    public void setCadence(int newValue){
        cadence = newValue;
    }

    public int getGear(){
    return gear;
    }

    public void setGear(int newValue){
        gear = newValue;
    }

    public int getSpeed(){
        return speed;
    }

    public void applyBrake(int decrement){
        speed -= decrement;
    }

    public void speedUp(int increment){
        speed += increment;
    }
}

Answer 1

Instance methods can access class variables as well.

A good example is a utility class: what do you do when you need a quick thing done, but creating an object would be cumbersome? That's right: static methods.

public static class Utils {
 public static void DoSomething(SomeClass x) { }
}

That way we can just call Utils.DoSomething(myObject);

instead of

Utils util = new Utils();
util.DoSomething(myObject);

Or, in your example, it keeps a count of how many bicycles are created in total. By saving it on class level, it will keep the state of the variable synced across all objects.

Answer 2

By class you mean static I assume? You can use static methods for utility classes. It keeps you from having to instantiate a class to access a method. For instance, I can write method that counts the number of letters in a String called getNumOfLetters and call it by using StringUtil.getNumOfLetters assuming String utils is the name of the class.