Static methods and variables are shared by all instances of the class. Static variables are initialized when a class is loaded whereas instance variables are initialized when an instance of the class is created. Static methods belong to a class, therefore, it can only access static members of the class and it can be called before instantiating the class.
class StaticCase {
static int staticCounter = 0;
int nonStaticCounter = 0;
StaticCase() {
staticCounter++; //class level
nonStaticCounter++; //instance level
}
}
class StaticCaseImpl {
//static method, entry point
public static void main(String... args) {
//StaticCase.nonStaticCounter, error, not a static variable
StaticCase sc1 = new StaticCase();
StaticCase sc2 = new StaticCase();
System.out.println("staticCounter sc1: " + sc1.staticCounter);
//output is staticCounter sc1: 2
//or in static context, StaticCase.staticCounter
System.out.println("nonStaticCounter sc1: " + sc1.nonStaticCounter);
//output is nonStaticCounter sc1: 1
System.out.println("staticCounter sc2: " + sc2.staticCounter);
//output is staticCounter sc2: 2
//or in static context, StaticCase.staticCounter
system.out.println("nonStaticCounter sc2: " + sc2.nonStaticCounter);
//output is nonStaticCounter sc2: 1
}
}
