Class Foo

Question

public class Foo {
int i;
static String s;
void imethod(){
static void smethod() {
Let f be an instance of Foo. Which of the following statements are correct?
System.out.println(f.i);
System.out.println(f.s);
f.imethod();
f.smethod();
System.out.println(Foo.i);
System.out.println(Foo.s);
Foo.imethod();
Foo.smethod();
Could someone explain how this works without giving away the answer?

Answer 1

anything declared as "static" in class are the class variable. for your example , static String s and static void smethod(). In order to use them, u had to use the class to call them Foo.i and Foo.smethod
So how about those not in static? yr int i, and void imethod() ?
Ans : only when u make instance of Foo class, then u can only use those objects to call those non-static variable and method. As follows:
Foo f = new foo;
f.i = 15;
f.smethod;
We should not directly access the i like above. That the rules of object-orientated programming, where we hide those details from people, so we will declared it as "private" and use instance method to set the value of i.