Certified Java Programmer Mock Exam

Question 1

class D {
  public static void main (String args[]) {
    boolean b1 = Integer.MIN_VALUE == 0x80000000;
    boolean b2 = Integer.MAX_VALUE == 0x7FFFFFFF;
    System.out.print(b1 + "," + b2);
}}

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

Question 2

Which methods of the java.lang.Double class return a primitive value?

Question 3

class G {
  public static void main (String[] args) {
    Long l1 = new Long("1"), l2 = new Long("1");
    int h1 = l1.hashCode(), h2 = l2.hashCode();
    StringBuffer s1 = new StringBuffer("1");
    StringBuffer s2 = new StringBuffer("1");
    int h3 = s1.hashCode(), h4 = s2.hashCode();
    System.out.print((l1.equals(l2) & (h1==h2)) + ",");
    System.out.print(s1.equals(s2) | (h3==h4));
}}

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

Question 4

class F {
  static String m(float f) {return "f";}
  static String m(Float f) {return "F";}
  public static void main (String[] args) {
    Float f1 = new Float(1);
    System.out.print(m(f1.parseFloat("1")));
    System.out.print(m(f1.floatValue()));
    System.out.print(m(f1.valueOf("1")));
}}

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

Question 5

class E {
  static String m1(boolean b) {return "b";}
  static String m1(Boolean b) {return "B";}
  public static void main(String[] args) {
    Boolean b1 = new Boolean(true);
    System.out.print(m1(Boolean.valueOf(null)));
    System.out.print(m1(b1.booleanValue()));
    System.out.println(m1(Boolean.TRUE));
}}

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

Question 6

class C {
  public static void main (String args[]) {
    String s1 = "1", s2 = "2";
    Byte b1 = Byte.parseByte(s1);
    Byte b2 = Byte.parseByte(s2);
    System.out.print(b1.byteValue() + b2.byteValue());
}}

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

Question 7

class A {
  public static void main (String[] args) {
    String s = "11";
    int i1 = Integer.parseInt(s);
    System.out.print(new Integer(i1).equals(new Integer(i1)) + ",");
    System.out.print(new Integer(i1).equals(new Integer(s))  + ",");
    System.out.print(new Integer(i1) == new Integer(i1));
}}

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

Question 8

Which method of the java.lang.Double class returns an instance of type Double?

Question 9

Which of the method invocation expressions would produce a run-time error?

Question 10

class B {
  public static void main (String[] args) {
    byte b1 = 11;
    System.out.print(new Integer(b1).equals(new Integer(b1)) + ",");
    System.out.print(new Integer(b1).equals(new Short(b1)) + ",");
    System.out.print(new Integer(b1).equals(new Byte(b1)));
}}

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

Question 11

Which methods of the java.lang.Double class declare a parameter of type String?

Question 12

Which of the method invocation expressions would produce a run-time error?

Question 13

Which of the following methods of the java.lang.Integer class returns a primitive int type?

Question 14

Which methods of the java.lang.Double class declare a NumberFormatException in the throws clause?

Question 15

class F {
  public static void main (String[] args) {
    Integer i1 = new Integer("1");
    Integer i2 = new Integer("1");
    int h1 = i1.hashCode(), h2 = i2.hashCode();
    StringBuffer sb1 = new StringBuffer("1");
    StringBuffer sb2 = new StringBuffer("1");
    int h3 = sb1.hashCode(), h4 = sb2.hashCode();
    System.out.print((h1==h2)+","+(h3==h4));
}}

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

Question 16

class F {
  public static void main (String args[]) {
    Double d1 = new Double("0x10");         // 1
    double d2 = Double.parseDouble("0x10"); // 2
    Double d3 = Double.valueOf("0x10");     // 3
    System.out.print(d1+","+d2+","+d3);
}}

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

Question 17

class G {
  public static void main (String[] args) {
    Integer i1 = new Integer("1"), i2 = new Integer("1");
    StringBuffer sb1 = new StringBuffer("1");
    StringBuffer sb2 = new StringBuffer("1");
    System.out.print(sb1.equals(sb2)+","+i1.equals(i2));
}}

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

Question 18

class H {
  public static void main (String[] args) {
    int i1, i2; Integer i3, i4;
    i1=new Integer(Integer.parseInt("1")).intValue();     // 1
    i3=new Integer(Integer.parseInt("1")).intValue();     // 2
    i2=Integer.parseInt(Integer.valueOf("1").toString()); // 3
    i4=Integer.parseInt(Integer.valueOf("1").intValue()); // 4
}}

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