PPT Slide

Instance vs. Class Variables

Suppose we wanted to track the total number of objects created.

Consider:

class Human {

String strName;

int iPopulation = 0;

public Human (String strName) {

this.strName = strName;

iPopulation++; //WRONG!

} // of constructor

} // of Human

Declares a strName String for each instance .

Thus, each Human will have its own name.

But . . .

Also declares an iPopulation counter for each instance of Human.

Thus, each Human will have its own iPopulation variable, each having a value of one. This makes no sense!