Dan Chisholm's
Java Programmer Certification Mock Exam

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Question 1

class GFC404 {
  private static int x=1;
  static void m1(int x, int y) {x++; y++;}
  public static void main (String[] args) {
    int y=3; m1(x, y);
    System.out.println(x + "," + y);
}}

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

Question 2

A class can not be called "tightly encapsulated" unless which of the following is true?

Question 3

Which of the following methods name the InterruptedException in its throws clause?

Question 4

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

Question 5

class SRC105 {
  public static void main(String[] args) {
    double d1 = Math.ceil(0.5);
    double d2 = Math.ceil(1.5);
    System.out.print(d1 + "," + d2);
}}

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

Question 6

class E {
  public static void main (String[] args) {
    Byte b1 = new Byte("1"), b2 = new Byte("1");
    System.out.print((b1==b2)+","+(b1.equals(b2)));
}}

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

Question 7

class B {
  public static void main (String args[]) {
    Integer a = new Integer(256);
    byte b = a.byteValue();
    short c = a.shortValue();
    int e = a.intValue();
    long f = a.longValue();
    float g = a.floatValue();
    double h = a.doubleValue();
    System.out.print(b+","+c+","+ (e+f+g+h == 4 * 256));
}}

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

Question 8

class F {
  static String m(long i) {return "long";}
  static String m(Long i) {return "Long";}
  static String m(double i) {return "double";}
  static String m(Double i) {return "Double";}
  static String m(String i) {return "String";}
  public static void main (String[] args) {
    System.out.print(m(Long.parseLong("1")));
}}

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

Question 9

class D {
  static boolean m(double v) {
    return(v != v == Double.isNaN(v));
  }
  public static void main (String args[]) {
    double d1 = Double.NaN;
    double d2 = Double.POSITIVE_INFINITY;
    double d3 = Double.MAX_VALUE;
    System.out.print(m(d1) + "," + m(d2) + "," + m(d3));
}}

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

Question 10

class D {
  public static void main (String[] args) {
    Boolean b1 = new Boolean("trUE");          // 1
    Boolean b2 = new Boolean("What's This?");  // 2
    Boolean b3 = new Boolean(null);            // 3
    System.out.print(b1 + "," + b2 + "," + b3);
}}

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

Question 11

class E {
  public static void main (String args[]) {
    String s1 = Float.toString(1.0);  // 1
    String s2 = Float.toString(1.0f); // 2
    String s3 = Float.toString(0xf);  // 3
    String s4 = Float.toString(010);  // 4
    String s5 = Float.toString('A');  // 5
}}

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

Question 12

class F {
  public static void main (String[] args) {
    Short s1 = new Short("1"), s2 = new Short("1");
    int a1 = s1.hashCode(), b1 = s2.hashCode();
    System.out.print((s1==s2)+","+(s1.equals(s2))+","+(a1==b1));
}}

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

Question 13

Which implementation of the List interface provides for the fastest insertion of a new element into the middle of the list?

Question 14

import java.util.*;
class GFC103 {
  public static void main (String args[]) {
    Object a1 = new TreeSet();
    System.out.print((a1 instanceof Set)+",");
    System.out.print(a1 instanceof SortedSet);
}}

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

Question 15

class A {
  static void m1 (B a, B b, B c, B d, B e, B f, B g, B h) {
    if (a.equals(b)) {System.out.print("A");}
    if (!c.equals(d)) {System.out.print("B");}
    if (e.hashCode() == f.hashCode()) {System.out.print("C");}
    if (g.hashCode() != h.hashCode()) {System.out.print("D");}
}}

Suppose that method m1 is invoked with eight instances of the same class and the output is ABCD. If the B.equals and B.hashCode methods are implemented according to the hash code contract, then which of the following statements must always be true?

Question 16

class A {A() throws Exception {}} // 1
class B extends A {B() throws Exception {}} // 2
class C extends A {} // 3

Which of the following statements is true?

Question 17

class JSC101 {
  void m1() {
    public int a;      // 1
    protected int b;   // 2
    private int c;     // 3
    static int d;      // 4
    transient int e;   // 5
    volatile int f;    // 6
    final int g = 1;   // 7
}}

Compile-time errors are generated at which lines?

Question 18

Which of the following statements is not true?

Question 19

class JSC205 {
  static int m1(int i) {return i;}     // 1
  static void m2(int i) {return i;}    // 2
  static int m3(int i) {return;}       // 3
  public static void main(String[] args) {
    System.out.print(""+m1(1)+m2(2)+m3(3)); // 4
}}

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

Question 20

class Black {
  public static void main(String args[]) {
    int[] i = {1,2,3,4,5};                  // 1
    long[] l = new long[5];                 // 2
    for (int j = 0; j < l.length(); j++) {  // 3
      l[j] = i[j];                          // 4
}}}

A compile-time error is generated at which line?

Question 21

class GFC218 {
  static void m(Object x) {System.out.print("Object");}
  static void m(String x) {System.out.print("String");}
  public static void main(String[] args) {m(null);}
}

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

Question 22

class P {
  static void printS1(){System.out.print("P.printS1 ");}
  void printS2() {System.out.print("P.printS2 ");}
  void printS1S2(){printS1();printS2();}
}
class Q extends P {
  static void printS1(){System.out.print("Q.printS1 ");}
  void printS2(){System.out.print("Q.printS2 ");}
  public static void main(String[] args) {
    new Q().printS1S2();
}}

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

Question 23

class D {
  D() {System.out.print("D");}
  class Z {Z(){System.out.print("Z");}}
  public static void main(String args[]) {
    new D.Z();
}}

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

Question 24

class A {void m1(A a) {System.out.print("A");}}
class B extends A {void m1(B b) {System.out.print("B");}}
class C extends B {void m1(C c) {System.out.print("C");}}
class D {
  public static void main(String[] args) {
    A c1 = new C(); C c2 = new C(); c1.m1(c2);
}}

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

Question 25

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?

Question 26

class MWC105 {
  static boolean b1;
  public static void main(String[] args) {
    boolean[] array = new boolean[1];
    boolean b2;
    System.out.print(b1+",");
    System.out.print(array[0]+",");
    System.out.print(b2);
}}

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

Question 27

class MWC205 {
  public static void main(String[] args) {
    int[][] a1 = {{1,2},{3,4,5},{6,7,8,9},{}};
    for (int i = 0; i < a1.length; i++) {
      System.out.print(a1[i].length+",");
}}}

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

Question 28

class GFC305 {
  static void m1(int[] i1, int[] i2) {
    int i = i1[0]; i1[0] = i2[0]; i2[0] = i;
  }
  public static void main (String[] args) {
    int[] i1 = {1}, i2 = {3}; m1(i1, i2);
    System.out.print(i1[0] + "," + i2[0]);
}}

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

Question 29

class A {String m1() {return "A.m1";}}
interface B {String m2();}
class C {
  static class D extends A implements B {
    public String m1() {return "D.m1";}
    public String m2() {return "D.m2";}
  }
  static A a1 = new A() implements B {
    public String m1() {return "m1";}
    public String m2() {return "m2";}
  };
  public static void main(String[] args) {
    System.out.print(a1.m1() + "," + new C.D().m2());
}}

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