A static field belongs to the class, not to one object. Every object sees the same static value. Use it for a shared counter or a constant. A static method can be called on the class name: Math.max(2, 9).
Static methods cannot read instance fields directly, because there is no particular object in scope. If the data belongs to one student, keep the method non-static.
Example
Each constructor adds 1 to the shared field. Two objects mean the field ends at 2.
public class Counter {
static int created = 0;
Counter() { created = created + 1; }
public static void main(String[] args) {
new Counter();
new Counter();
System.out.println(Counter.created);
}
}Math is a class of static helpers. You do not write new Math(). You call Math.sqrt or Math.max on the class.
