Certified Java Programmer Mock Exam

Question 1

Which of the instance creation expressions produce a run-time error?

Question 2

class C {
  public static void main(String[] args) {
    Boolean b1 = Boolean.valueOf(true);
    Boolean b2 = Boolean.valueOf(true);
    Boolean b3 = Boolean.valueOf("TrUe");
    Boolean b4 = Boolean.valueOf("tRuE");
    System.out.print((b1==b2) + ",");
    System.out.print((b1.booleanValue()==b2.booleanValue()) + ",");
    System.out.println(b3.equals(b4));
}}

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

Question 3

Which of the following class instance creation expressions would generate a run-time error?

Question 4

class E {
  public static void main (String[] args) {
    Byte b1 = new Byte("1"), b2 = new Byte("1");
    System.out.print((b1==b2)+","+(b1.equals(b2)));
}}

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

Question 5

class B {
  public static void main (String args[]) {
    Integer a = new Integer(256);
    byte b = a.byteValue();
    short c = a.shortValue();
    int e = a.intValue();
    long f = a.longValue();
    float g = a.floatValue();
    double h = a.doubleValue();
    System.out.print(b+","+c+","+ (e+f+g+h == 4 * 256));
}}

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

Question 6

class D {
  static boolean m(double v) {
    return(v != v == Double.isNaN(v));
  }
  public static void main (String args[]) {
    double d1 = Double.NaN;
    double d2 = Double.POSITIVE_INFINITY;
    double d3 = Double.MAX_VALUE;
    System.out.print(m(d1) + "," + m(d2) + "," + m(d3));
}}

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

Question 7

class F {
  static String m(long i) {return "long";}
  static String m(Long i) {return "Long";}
  static String m(double i) {return "double";}
  static String m(Double i) {return "Double";}
  static String m(String i) {return "String";}
  public static void main (String[] args) {
    System.out.print(m(Long.parseLong("1")));
}}

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

Question 8

class E {
  public static void main (String args[]) {
    String s1 = Float.toString(1.0);  // 1
    String s2 = Float.toString(1.0f); // 2
    String s3 = Float.toString(0xf);  // 3
    String s4 = Float.toString(010);  // 4
    String s5 = Float.toString('A');  // 5
}}

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

Question 9

class D {
  public static void main (String[] args) {
    Boolean b1 = new Boolean("trUE");          // 1
    Boolean b2 = new Boolean("What's This?");  // 2
    Boolean b3 = new Boolean(null);            // 3
    System.out.print(b1 + "," + b2 + "," + b3);
}}

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

Question 10

class F {
  public static void main (String[] args) {
    Short s1 = new Short("1"), s2 = new Short("1");
    int a1 = s1.hashCode(), b1 = s2.hashCode();
    System.out.print((s1==s2)+","+(s1.equals(s2))+","+(a1==b1));
}}

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

Question 11

class E {
  public static void main (String[] args) {
    Byte b1 = new Byte("1"), b2 = new Byte("1");
    int a = b1.hashCode(), b = b2.hashCode();
    System.out.print((b1.equals(b2))+","+(a==b));
}}

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

Question 12

class E {
  static String m(int i) {return "int primitive";}
  static String m(Integer i) {return "Integer instance";}
  static String m(double i) {return "double primitive";}
  static String m(Double i) {return "Double instance";}
  static String m(String i) {return "String instance";}
  public static void main (String[] args) {
    System.out.print(m(Integer.parseInt("1")));
}}

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

Question 13

Which of the following methods are static members of the java.lang.Double class?

Question 14

class F {
  static String m(long i) {return "long";}
  static String m(Long i) {return "Long";}
  static String m(double i) {return "double";}
  static String m(Double i) {return "Double";}
  static String m(String i) {return "String";}
  public static void main (String[] args) {
    System.out.print(m(Long.parseLong("1L")));
}}

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

Question 15

class E {
  static String m(float f) {return "f";}
  static String m(Float f) {return "F";}
  public static void main (String[] args) {
    System.out.print(m(Float.parseFloat("1")));
    System.out.print(m(Float.floatValue()));
    System.out.print(m(Float.valueOf("1")));
}}

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

Question 16

class D {
  public static void main (String[] args) {
    Boolean b1 = Boolean.valueOf("trUE");           // 1
    Boolean b2 = Boolean.valueOf("Even more true"); // 2
    Boolean b3 = Boolean.valueOf(null);             // 3
    System.out.print((b1==b2) + ",");
    System.out.print((b2==b3) + ",");
    System.out.println(b3==b1);
}}

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

Question 17

class E {
  static String m(short s) {return "p";}
  static String m(Short s) {return "S";}
  public static void main (String[] args) {
    Short s1 = new Short("1");
    System.out.print(m(s1.shortValue())+",");
    System.out.print(m(Short.parseShort("1"))+",");
    System.out.print(m(Short.valueOf("1")));
}}

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

Question 18

class F {
  public static void main (String[] args) {
    System.out.print(Byte.MIN_VALUE+","+Byte.MAX_VALUE);
}}

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