Certified Java Programmer Mock Exam

Question 1

class MCZ24 {
  public static void main (String[] args) {
    char a = 061;      // 1
    char b = '\61';    // 2
    char c = '\061';   // 3
    char d = 0x0031;   // 4
    char e = '\u0031'; // 5
    System.out.print(""+a+b+c+d+e);
}}

A compile-time error is generated at which line?

Question 2

class MWC114 {
  public static void main(String[] s) {
    String s1 = new String("ABCDEFG"), s2 = new String("EFGHIJ");
    String s3 = s1.substring(4,7), s4 = s2.substring(0,3);
    System.out.println((s3 == s4) + "," + (s3 + s4).equals(s4 + s3));
}}

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

Question 3

class SRC117 {
  public static void main (String[] args) {
    double d1 = Math.random();
    boolean b1 = (d1 < 0.0), b2 = (d1 <= 0.0), b3 = (d1 == 0.0);
    boolean b4 = (d1 >= 0.0), b5 = (d1 < 1.0), b6 = (d1 <= 1.0);
    boolean b7 = (d1 == 1.0), b8 = (d1 >= 1.0), b9 = (d1 > 1.0);
}}

Which of the boolean variables will never be initialized to the value true?

Question 4

class RedException extends Exception {}
class BlueException extends Exception {}
class White {
  void m1() throws RedException {throw new RedException();}
  public static void main (String[] args) {
    White white = new White();
    int a,b,c,d; a = b = c = d = 0;
    try {white.m1(); a++;}
      catch (RedException e) {b++;}
      catch (BlueException e) {c++;}
      finally {d++;}
    System.out.print(a+","+b+","+c+","+d);
}}

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

Question 5

Which of the following are command-line switches used to disable assertions in non-system classes?

Question 6

interface A {void m1();}                      // 1
class B implements A {public void m1() {}}    // 2
class C implements A {protected void m1() {}} // 3
class D implements A {private void m1() {}}   // 4
class E implements A {void m1() {}}           // 5 

Compile-time errors are generated at which lines?

Question 7

class MCZ23 {
  public static void main (String[] args) {
    // Insert code here.
}}

Which of the following lines can be inserted at the specified location without generating a compile-time error?

Question 8

class MWC115 {
  public static void main(String[] s) {
    String s1 = new String("ABCDEFG"), s2 = s1.substring(0,3);
    String s3 = s1.substring(4,6); char c1 = s1.charAt(3);
    System.out.println(s2.concat(String.valueOf(c1)).concat(s3));
}}

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

Question 9

Which method of the java.lang.Math class is not static?

Question 10

import java.util.*;
class GFC116 {
  public static void main (String[] args) {
    Object x = new Vector().elements();
    System.out.print((x instanceof Enumeration)+",");
    System.out.print((x instanceof Iterator)+",");
    System.out.print(x instanceof ListIterator);
}}

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

Question 11

Which of the following are command-line switches used to disable assertions in non-system classes?

Question 12

class EBH025 {
  public static void main (String args[]) {
    int i1 = 0xffffffff, i2 = i1 << 33;
    int i3 = i1 << (33 & 0x1f);
    System.out.print(Integer.toHexString(i2) + ",");
    System.out.print(Integer.toHexString(i3));
}}

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

Question 13

Which of the following are true statements?

Question 14

Some of the following method names are overloaded and some are not. Which of the following method names are overloaded such that for each of the following four primitive types int, long, float and double there is at least one corresponding method that returns that type?

Question 15

import java.util.*;
class GFC117 {
  public static void main (String[] args) {
    Object i1 = new HashMap(), i2 = new TreeMap();
    System.out.print((i1 instanceof SortedMap)+",");
    System.out.print((i2 instanceof SortedMap)+",");
    System.out.print(i1 instanceof Collection);
}}

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

Question 16

When a thread is created and started, what is its initial state?

Question 17

Which of these classes provides the specified features?

Question 18

import java.util.*;
class GFC114 {
  public static void main (String[] args) {
    Object a = new ArrayList();
    System.out.print((a instanceof Collections)+",");
    System.out.print((a instanceof Arrays)+",");
    System.out.print(a instanceof List);
}}

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

Question 19

Which of the following are true statements?

Question 20

Which of these classes provides the specified features?

Question 21

interface Z {void m1();}  // 1
class A implements Z {void m1() {}} // 2
class B implements Z {public void m1() {}} // 3
abstract class C implements Z {public abstract void m1();} // 4

A Compile-time error is generated at which line?

Question 22

Which of the following are true statements?

Question 23

class MWC116 {
  public static void main(String[] args) {
    String s1 = " B C D E ";
    System.out.print('A' + s1.trim() + 'F');
}}

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

Question 24

Suppose that you would like to create a new instance of a class that implements the Set interface, and you would like the new instance to be initialized with the elements of an existing Set. If you would like the iteration order of the new Set to be the same as that of the existing Set, then which concrete implementation of the Set interface should be used for the new instance?

Question 25

class JMM115 {
  static int m1(String s, int i) {
    System.out.print(s + i);
    return i;
  }
  public static void main (String[] args) {
    int i = 0, j = 0, k = 0;
    do while (m1("i", ++i) < 2)
      System.out.print("k" + ++k);
    while (m1("j", ++j) < 2);
}}

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

Question 26

class EBH024 {
  public static void main(String[] args) {
    int i1 = 15;
    String b1 = (i1>30)?"Red":(i1>20)?"Green":(i1>10)?"Blue":"Violet";
    String b2 = (i1>30)?"Red":((i1>20)?"Green":((i1>10)?"Blue":"Violet"));
    System.out.println(b1 + "," + b2);

}}

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

Question 27

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();      // 1
    a1.m2();      // 2
   ((B)a1).m1();  // 3
   ((B)a1).m2();  // 4
}}

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

Question 28

class JMM116 {
  static int m1(String s, int i) {
    System.out.print(s + i);
    return i;
  }
  public static void main (String[] args) {
    int j = 0;
    for (int i = m1("A",0); m1("B",i) < 2; m1("C",++i)) {
      m1("J",++j);
    }
}}

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