Dan Chisholm's
Java Programmer Certification Mock Exam

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Question 1

Which of the following are not methods of the java.lang.String class?

a. append
b. concat
c. delete
d. insert
e. replace
f. substring
g. valueOf

Question 2

Which of these methods modify the contents of the String instance on which it is invoked?

a. append
b. concat
c. delete
d. insert
e. replace
f. substring
g. valueOf
h. None of the above.

Question 3

Which of these methods is a static member of the java.lang.String class?

a. append
b. concat
c. delete
d. insert
e. replace
f. substring
g. valueOf
h. None of the above.

Question 4

class MWC106 {
  static void m1(String s) {
    s = s.trim(); s = s.concat("D");
  }
  public static void main(String[] s) {
    String s1 = "A", s2 = " B ", s3 = "C";
    m1(s2);
    System.out.print(s1 + s2 + s3);
}}

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

a. Prints: ABC
b. Prints: A B C
c. Prints: ABCD
d. Prints: ABDC
e. Prints: A B CD
f. Prints: A B DC
g. Compile-time error
h. Run-time error
i. None of the above

Question 5

class MWC107 {
  public static void main(String[] s) {
    String s1 = "A", s2 = " B ", s3 = "C";
    s2.trim(); s3.concat("D");
    System.out.print(s1 + s2 + s3);
}}

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

a. Prints: ABC
b. Prints: A B C
c. Prints: ABCD
d. Prints: ABDC
e. Prints: A B CD
f. Prints: A B DC
g. Compile-time error
h. Run-time error
i. None of the above

Question 6

class MWC108 {
  public static void main(String[] s) {
    String s1 = "A", s2 = " B ", s3 = "C";
    s2.trim(); s3.append("D");
    System.out.print(s1 + s2 + s3);
}}

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

a. Prints: ABC
b. Prints: A B C
c. Prints: ABCD
d. Prints: ABDC
e. Prints: A B CD
f. Prints: A B DC
g. Compile-time error
h. Run-time error
i. None of the above

Question 7

class MWC110 {
  static void m1(String s1, String s2) {
    s1.insert(1,"D"); s1 = s1 + s2;
  }
  public static void main(String[] s) {
    String s1 = "A", s2 = "B";
    m1(s1,s2);
    System.out.print(s1 + s2);
}}

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

a. Prints: AB
b. Prints: ABB
c. Prints: ADB
d. Prints: ADBB
e. Compile-time error
f. Run-time error
g. None of the above

Question 8

class MWC111 {
  static void m1(String s1) {
    s1.replace('A','Y'); System.out.print(s1);
  }
  static void m2(String s1) {
    s1 = s1.replace('A','Z'); System.out.print(s1);
  }
  public static void main(String[] s) {
    String s1 = "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: YZA
c. Prints: YAA
d. Prints: AZA
e. Prints: AZZ
f. Compile-time error
g. Run-time error
h. None of the above

Question 9

class MWC112 {
  static void m1(String s1) {
    s1 = s1.toUpperCase(); System.out.print(s1);
  }
  static void m2(String s1) {
    s1.toLowerCase(); System.out.print(s1);
  }
  public static void main(String[] s) {
    String s1 = "Ab";
    m1(s1); m2(s1);
    System.out.print(s1);
}}

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

a. Prints: AbAbAb
b. Prints: ABabab
c. Prints: ABabAb
d. Prints: ABAbAb
e. Prints: Ababab
f. Compile-time error
g. Run-time error
h. None of the above

Question 10

class MWC113 {
  public static void main(String[] s) {
    String s1 = "1", s2 = "2", s3 = s1 + s2;
    s1 += s2; s3 += s1;
    System.out.println(s3);
}}

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

a. Prints: 3
b. Prints: 6
c. Prints: 33
d. Prints: 1212
e. Compile-time error
f. Run-time error
g. None of the above

Question 11

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?

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 12

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?

a. Prints: "ABCDEFG"
b. Prints: "ABCEFG"
c. Prints: "ABCDDEFG"
d. Prints: "ABCDEF"
e. Prints: "ABCEF"
f. Prints: "ABCDDEF"
g. Compile-time error
h. Run-time error
i. None of the above

Question 13

class MWC118 {
  public static void main(String[] args) {
    byte[] b = {'a', 'b', 'c'};
    char[] c = {'a', 'b', 'c'};
    String s = "abc";
    StringBuffer sb = new StringBuffer("abc");
    byte b2 = 'a';
    char c2 = 'a';
    String s1 = new String(b);   // 1
    String s2 = new String(c);   // 2
    String s3 = new String(s);   // 3
    String s4 = new String(sb);  // 4
    String s5 = new String(b2);  // 5
    String s6 = new String(c2);  // 6
}}

Compile-time errors are generated at which lines?

a. 1
b. 2
c. 3
d. 4
e. 5
f. 6

Question 14

class MWC101 {
  public static void main(String[] args) {
    String s1 = "A", s2 = "a", s3 = "b";
    s1.toLowerCase(); s3.replace('b','a');
    System.out.print((s1.equals(s2)) + "," + (s2.equals(s3)));
}}

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 15

class MWC102 {
  public static void main (String[] args) {
    String s1 = "ABCDE";
    System.out.print(s1.substring(1,2)+s1.substring(3));
}}

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

a. Prints: AABC
b. Prints: ACDE
c. Prints: ABABC
d. Prints: ABCDE
e. Prints: BABCD
f. Prints: BDE
g. Prints: BCABCD
h. Prints: BCDE
i. Compile-time error
j. Run-time error
k. None of the above

Question 16

class MWC104 {
  public static void main (String[] args) {
    char[] c = {'a','b','c','d'};
    String s1 = new String(c);
    boolean b = true;
    for (int i = 0; i < s1.length; i++) {
      b &= (c[i] == s1.charAt(i));
    }
    System.out.print(b);
}}

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

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

Question 17

class MWC109 {
  public static void main(String args[]) {
    String a = "A", b = "B", c = a+b, d = a+b;
    System.out.print(((a+b)==(a+b)) + ",");
    System.out.print((c==d) + ",");
    System.out.print(c.equals(d));
}}

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

a. Prints: false,false,false
b. Prints: false,false,true
c. Prints: false,true,false
d. Prints: false,true,true
e. Prints: true,false,false
f. Prints: true,false,true
g. Prints: true,true,false
h. Prints: true,true,true

Question 18

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?

a. Prints: ABCDEF
b. Prints: A B C D E F
c. Prints: A BCDEF
d. Prints: ABCDE F
e. Prints: AB C D EF
f. Compile-time error
g. Run-time error
h. None of the above

Question 19

class MWC117 {
  public static void main (String[] args) {
    System.out.print(String.valueOf(1) + String.valueOf(2));
    String s1 = "S1";
    String s2 = s1.toString();
    System.out.print("," + (s1==s2));
}}

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

a. Prints: 3,false
b. Prints: 3,true
c. Prints: 12,false
d. Prints: 12,true
e. Compile-time error
f. Run-time error
g. None of the above
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