Dan Chisholm's
Java Programmer Certification Mock Exam

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Question 1

class MWC204 {
  static void m1(StringBuffer s1) {
    s1 = s1.append("B"); System.out.print(s1);
  }
  static void m2(StringBuffer s1) {
    s1.append("C"); System.out.print(s1);
  }
  public static void main(String[] s) {
    StringBuffer s1 = new StringBuffer("A");
    m1(s1); m2(s1);
    System.out.print(s1);
}}

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

a. Prints: AAA
b. Prints: ABAA
c. Prints: ABACA
d. Prints: ABABAB
e. Prints: ABABCAB
f. Prints: ABABCABC
g. Prints: ABCABCABC
h. Compile-time error
i. Run-time error
j. None of the above

Question 2

class MWC205 {
  static void m1(StringBuffer s1) {
    s1.append("B"); System.out.print(s1);
  }
  static void m2(StringBuffer s1) {
    s1 = new StringBuffer("C"); System.out.print(s1);
  }
  public static void main(String[] s) {
    StringBuffer s1 = new StringBuffer("A");
    m1(s1); m2(s1);
    System.out.print(s1);
}}

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

a. Prints: AAA
b. Prints: ABCA
c. Prints: ABCAB
d. Prints: ABCABC
e. Prints: ABCAC
f. Prints: ABABCABC
g. Compile-time error
h. Run-time error
i. None of the above

Question 3

class MWC200 {
  public static void main (String[] args) {
    String s1 = "ABC";
    StringBuffer s2 = new StringBuffer(s1);
    System.out.print(s2.equals(s1) + "," + s1.equals(s2));
}}

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

a. Prints: false,false
b. Prints: false,true
c. Prints: true,false
d. Prints: true,true
e. Compile-time error
f. Run-time error
g. None of the above

Question 4

class MWC201 {
  public static void main (String[] args) {
    String s1 = new String("ABC"), s2 = new String("ABC");
    StringBuffer sb1 = new StringBuffer(s1);
    StringBuffer sb2 = new StringBuffer(s2);
    System.out.print(s1.equals(s2) + "," + sb1.equals(sb2));
}}

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

a. Prints: false,false
b. Prints: false,true
c. Prints: true,false
d. Prints: true,true
e. Compile-time error
f. Run-time error
g. None of the above

Question 5

class MWC202 {
  public static void main (String[] args) {
    StringBuffer sb1 = new StringBuffer("ABC");
    StringBuffer sb2 = new StringBuffer("ABC");
    System.out.print((sb1==sb2)+","+sb1.equals(sb2));
}}

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

a. Prints: false,false
b. Prints: false,true
c. Prints: true,false
d. Prints: true,true
e. Compile-time error
f. Run-time error
g. None of the above

Question 6

class MWC203 {
  public static void main (String[] args) {
    String s1 = new String("ABC"), s2 = new String("ABC");
    StringBuffer sb1 = new StringBuffer(s1);
    StringBuffer sb2 = new StringBuffer(s2);
    boolean b1 = s1.hashCode() == s2.hashCode();
    boolean b2 = sb1.hashCode() == sb2.hashCode();
    System.out.print(b1 + "," + b2);
}}

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

a. Prints: false,false
b. Prints: false,true
c. Prints: true,false
d. Prints: true,true
e. Compile-time error
f. Run-time error
g. None of the above
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