Certified Java Programmer Mock Exam

Question 1

class Basics {
  static int x=1;
  void m(int i) {x++;i++;}
  public static void main (String[] args) {
    int y=3;
    m(y);
    System.out.println(x + "," + y);
  }
}

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

Question 2

class Basics {
  private static int x=1;
  static void m(int i) {x++;i++;}
  public static void main (String[] args) {
    int y=3;
    m(y);
    System.out.println(x + "," + y);
  }
}

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

Question 3

interface A {
  final void m6();        // 1
  synchronized void m7(); // 2
  strictfp void m8();     // 3
  native void m9();       // 4
}

Compile-time errors are generated at which lines?

Question 4

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

Question 5

interface A {
  int a = 1;                        // 1
  public int b = 2;                 // 2
  public static int c = 3;          // 3
  public static final int d = 4;    // 4
}

Which of the field declarations result in a compile-time error?

Question 6

class L {
  static String m(float i) {return "float";}
  static String m(double i) {return "double";}
  public static void main (String[] args) {
    int 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 7

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

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 c1 = new C();
    A c2 = new C();
    A c3 = new C();
    C c4 = new C();
    c1.m1(c4);
    c2.m1(c4);
    c3.m1(c4);
  }
}

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 Silver {
6.    public static void main(String []args) {
7.      Base[] base = {new Base()};
8.      Sub sub[] = new Sub[1];
9.      Object obj = base;
10.     sub = (Sub[])obj;
11.     I1 []i1 = (I1[])obj;
12.   }
13. }

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

Question 10

class P {
  static void printS1(){System.out.print("P.printS1 ");}
  void printS2() {System.out.print("P.printS2 ");}
  void printS1S2(){printS1();printS2();}
}

class Q extends P {
  static void printS1(){System.out.print("Q.printS1 ");}
  void printS2(){System.out.print("Q.printS2 ");}
  public static void main(String[] args) {
    new Q().printS1S2();
  }
}

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

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

Question 12

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) {
    A a;
    B b;
    m(null,null);
    m(a=null,b=null);
    m(b, a);
  }
}

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

Question 13

 1. interface I1 {}
 2. interface I2 {}
 3. class Base implements I1 {}
 4. class Sub extends Base implements I2 {}
 5.
 6. class Red {
 7.   public static void main(String args[]) {
 8.     Sub s1 = new Sub();
 9.     I2 i2 = s1;
10.     I1 i1 = s1;
11.     Base base = s1;
12.     Sub s2 = (Sub)base;
13.   }
14. }

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

Question 14

1.  interface I10 {
2.    String name = "I10";
3.    String s10 = "I10.s10";
4.  }
5.  interface I20 {
6.    String name = "I20";
7.    String s20 = "I20.s20";
8.  }
9.  class C20 implements I10, I20 {
10.   public static void main(String[] args) {
11.     System.out.print(I10.s10+",");
12.     System.out.print(I20.s20+",");
13.     System.out.print(I20.name);
14.   }
15. }

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

Question 15

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

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

Question 16

class T {
  private int i1, i2;
  void printI1I2() {System.out.print("T: i1=" + i1 + ", i2=" + i2);}
  T(int i1, int i2) {
    this.i1=i1;this.i2=i2;
  }
}

class U extends T {
  private int i1, i2;
  void printI1I2() {System.out.print("U: i1=" + i1 + ", i2=" + i2);}
  U(int i1, int i2) {
    this.i1=i1;this.i2=i2;
  }
  public static void main(String[] args) {
    T t = new U(1,2);
    t.printI1I2();
  }
}

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

Question 17

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();
    A b1 = new B();
    A c1 = new C();
    C c4 = new C();
    a1.m1(c4);
    b1.m1(c4);
    c1.m1(c4);
  }
}

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

Question 18

class A {public void m1() {System.out.print("A1");}}
class B extends A {
  public void m1() {System.out.print("B1");}
  public void m2() {System.out.print("B2");}
}
class C {
  public static void main(String[] args) {
    A a1 = new B();
    a1.m1();
    a1.m2();
    ((B)a1).m1();
    ((B)a1).m2();
  }
}

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