Java Language Classes and Objects Object Member vs Static Member
Example
With this class:
class ObjectMemberVsStaticMember {
static int staticCounter = 0;
int memberCounter = 0;
void increment() {
staticCounter ++;
memberCounter++;
}
}
the following code snippet:
final ObjectMemberVsStaticMember o1 = new ObjectMemberVsStaticMember();
final ObjectMemberVsStaticMember o2 = new ObjectMemberVsStaticMember();
o1.increment();
o2.increment();
o2.increment();
System.out.println("o1 static counter " + o1.staticCounter);
System.out.println("o1 member counter " + o1.memberCounter);
System.out.println();
System.out.println("o2 static counter " + o2.staticCounter);
System.out.println("o2 member counter " + o2.memberCounter);
System.out.println();
System.out.println("ObjectMemberVsStaticMember.staticCounter = " + ObjectMemberVsStaticMember.staticCounter);
// the following line does not compile. You need an object
// to access its members
//System.out.println("ObjectMemberVsStaticMember.staticCounter = " + ObjectMemberVsStaticMember.memberCounter);
produces this output:
o1 static counter 3
o1 member counter 1
o2 static counter 3
o2 member counter 2
ObjectMemberVsStaticMember.staticCounter = 3
Note: You should not call static members on objects, but on classes. While it does not make a difference for the JVM, human readers will appreciate it.
static members are part of the class and exists only once per class. Non-static members exist on instances, there is an independent copy for each instance. This also means that you need access to an object of that class to access its members.
