Section 9.7 Check Point Questions3 questions 

Suppose that the class F is defined in (a). Let f be an instance of F. Which of the statements in (b) are correct?

(a)
public class F {
  int i;
  static String s;

  void imethod() {
  }

  static void smethod() {
  }
}

(b)
System.out.println(f.i);
System.out.println(f.s);
f.imethod();
f.smethod();
System.out.println(F.i);
System.out.println(F.s);
F.imethod();
F.smethod();

Add the static keyword in the place of ? if appropriate.

public class Test { 
  int count; 
            
  public ? void main(String[] args) { 
    ...
  }
            
  public ? int getCount() { 
    return count;
  } 
  
  public ? int factorial(int n) { 
    int result = 1;
    for (int i = 1; i <= n; i++)
      result *= i; 
    return result;
  }
}

1. Can you invoke an instance method or reference an instance variable from a static method?
2. Can you invoke a static method or reference a static variable from an instance method?
3. What is wrong in the following code?

 1  public class C {
 2    Circle c = new Circle();
 3
 4    public static void main(String[] args) {
 5      method1();
 6    }
 7
 8    public void method1() {
 9      method2();
10    }
11
12    public static void method2() {
13      System.out.println("What is radius " + c.getRadius());
14    }
15  }