Certified Java Programmer Mock Exam

Question 1

class A {
  void m1() {System.out.print("A.m1");}
}
class B extends A {
  void m1() {System.out.print("B.m1");}
  static void m1(String s) {System.out.print(s+",");}
}
class C {
  public static void main (String[] args) {
    B.m1("main");
    new B().m1();
  }
}

What is the result of attempting to compile and run the above program?

Question 2

interface A {
  int i = 1;
  int m1();
}
interface B extends A {
  int i = 10;
  int m1();
}
class C implements B {
  public int m1() {return ++i;}
  public static void main(String[] args) {
    System.out.print(new C().m1());
  }
}

What is the result of attempting to compile and run the program?

Question 3

Which of the following are modifiers that can be applied to a field declaration within an interface?

Question 4

interface A {
  String s1 = "A";
  String m1();        
}
interface B implements A {
  String s1 = "B";
  String m1();             
}
class C implements B {
  public String m1() {return s1;}
  public static void main(String[] args) {
    A a = new C();
    System.out.print(a.m1());
  }
}

What is the result of attempting to compile and run the program?

Question 5

class A {String s1 = "A";}
class B extends A {String s1 = "B";}
class C extends B {String s1 = "C";}
class D {
  static void m1(A x) {System.out.print(x.s1);}
  static void m1(B x) {System.out.print(x.s1);}
  static void m1(C x) {System.out.print(x.s1);}
  public static void main(String[] args) {
    A a; B b; C c;
    a = b = c = new C();
    m1(a);m1(b);m1(c);
  }
}

What is the result of attempting to compile and run the above program?

Question 6

class E {
  void printS1(){System.out.print("E.printS1 ");}
  static void printS2() {System.out.print("E.printS2");}
}

class F extends E {
  void printS1(){System.out.print("F.printS1 ");}
  static void printS2() {System.out.print("F.printS2");}
  public static void main (String args[]) {
    E x = new F();
    x.printS1(); x.printS2();
  }
}

What is the result of attempting to compile and run the above program?

Question 7

class A {static void m() {System.out.print("A");}}
class B extends A {static void m() {System.out.print("B");}}
class C extends B {static void m() {System.out.print("C");}}
class D {
  public static void main(String[] args) {
    C c = new C();
    c.m();
    B b = c;
    b.m();
    A a = b;
    a.m();
  }
}

What is the result of attempting to compile and run the above program?

Question 8

class A {
  void m1(A a) {System.out.print("A");}
}
class B extends A {
  void m1(B b) {System.out.print("B");}
}
class C extends B {
  void m1(C c) {System.out.print("C");}
}
class D {
  public static void main(String[] args) {
    A a1 = new A();
    B b1 = new B();
    C c1 = new C();
    A c2 = new C();
    c2.m1(a1);
    c2.m1(b1);
    c2.m1(c1);
  }
}

What is the result of attempting to compile and run the program?

Question 9

 1. interface I1 {}
 2. interface I2 {}
 3. class Base implements I1 {}
 4. class Sub extends Base implements I2 {}
 5. class Yellow {
 6.   public static void main(String args[]) {
 7.     Base base = new Sub();
 8.     I1 i1 = base;
 9.     Sub sub = (Sub)base;
10.     I2 i2 = (Sub)base;
11.   }
12. }

What is the result of attempting to compile and run the above program?

Question 10

class A {}
class B {
  static void m(Object x) {System.out.print("Object");}
  static void m(String x) {System.out.print("String");}
  public static void main(String[] args) {
    m(null);
  }
}

What is the result of attempting to compile and run the above program?

Question 11

class A {}
class B extends A {}
class C extends B {
  static void m(A x, A y) {System.out.print("AA");}
  static void m(A x, B y) {System.out.print("AB");}
  static void m(B x, A y) {System.out.print("BA");}
  static void m(B x, B y) {System.out.print("BB");}
  public static void main(String[] args) {
    C c = new C();
    m(c, c);
  }
}

What is the result of attempting to compile and run the above program?

Question 12

interface Z {void m1();}  // 1
class D implements Z {public final void m1() {}} // 2
class E implements Z {public synchronized void m1() {}} // 3
class F implements Z {public strictfp void m1() {}} // 4
class G implements Z {public native void m1();} // 5

Compile-time errors are generated at which lines?

Question 13

class A {
  void m1(A a) {System.out.print("A");}
}
class B extends A {
  void m1(B b) {System.out.print("B");}
}
class C extends B {
  void m1(C c) {System.out.print("C");}
}
class D {
  public static void main(String[] args) {
    A c1 = new C();
    B c2 = new C();
    C c3 = new C();
    C c4 = new C();
    c4.m1(c1);
    c4.m1(c2);
    c4.m1(c3);
  }
}

What is the result of attempting to compile and run the program?

Question 14

class Leg{}
class Fur{}
abstract class Pet {
  public abstract void eat();
  public abstract void sleep();
}
class Dog extends Pet {
  Leg leftFront = new Leg();
  Leg rightFront = new Leg();
  Leg leftRear = new Leg();
  Leg rightRear = new Leg();
  Fur fur = new Fur();
  public Fur shed() {return fur;}
  public void eat() {}
  public void sleep() {}
}
class Cat extends Dog {
  public void ignoreOwner() {}
  public void climbTree() {}
}

Which of the following are true statements?

Question 15

class L {
  static String m(float i) {return "float";}
  static String m(double i) {return "double";}
  public static void main (String[] args) {
    char a = 1;
    long b = 2;
    System.out.print(m(a)+","+ m(b));
  }
}

What is the result of attempting to compile and run the above program?

Question 16

1.  interface I1 {}
2.  interface I2 {}
3.  class Base implements I1 {}
4.  class Sub extends Base implements I2 {}
5.  class Gray {
6.    public static void main(String []args) {
7.      Base[] base = {new Base()};
8.      Sub sub[] = {new Sub()};
9.      Object obj = sub;
10.     base = obj;
11.   }
12. }

What is the result of attempting to compile and run the above program?

Question 17

class A {}
class B {
  static void m(Object x) {System.out.print("Object");}
  static void m(String x) {System.out.print("String");}
  static void m(A x) {System.out.print("A");}
  public static void main(String[] args) {
    m(null);
  }
}

What is the result of attempting to compile and run the above program?