Certified Java Programmer Mock Exam

Question 1

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

Question 2

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

Question 3

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

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?

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?

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?

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?

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?

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?

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?

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?

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?

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?

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?

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?

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?

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?

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?

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?