Dan Chisholm's
Java Programmer Certification Mock Exam

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I would also like to read your response to the following questions.

Question 1

Which of these words belong to the set of Java keywords?

a. declare
b. global
c. const
d. preserve
e. continue
f. Float
g. extends
h. select
i. break
j. dim
k. instanceOf

Question 2

class MCZ15 {
  public static void main (String[] args) {
    float a = 1.1e1f;  // 1
    float b = 1e-1F;   // 2
    float c = .1e1f;   // 3
    double d = .1d;    // 4
    double e = 1D;     // 5
}}

A compile-time error is generated at which line?

a. 1
b. 2
c. 3
d. 4
e. 5
f. None of the above

Question 3

class JSC105 {
  private static int x; protected static int y; public static int z;
  public static void main (String[] args) {System.out.println(x+y+z);}
}

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

a. Prints nothing.
b. Prints an undefined value.
c. Prints: null
d. Prints: 0
e. Run-time error
f. Compile-time error
g. None of the above

Question 4

class ColorException extends Exception {}
class WhiteException extends ColorException {}
class White {
  void m1() throws ColorException {throw new WhiteException();}
  void m2() throws WhiteException {}
  public static void main (String[] args) {
    White white = new White();
    int a,b,d,f; a = b = d = f = 0;
    try {white.m1(); a++;} catch (ColorException e) {b++;}
    try {white.m2(); d++;} catch (WhiteException e) {f++;}
    System.out.print(a+","+b+","+d+","+f);
}}

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

a. Prints: 0,1,0,0
b. Prints: 1,1,0,0
c. Prints: 0,1,1,0
d. Prints: 1,1,1,0
e. Prints: 1,1,1,1
f. Compile-time error
g. Run-time error
h. None of the above

Question 5

Which of the following are modifiers that can be applied to a field declaration within an interface?

a. abstract
b. const
c. final
d. private
e. protected
f. public

Question 6

class JJF6 {
  char c1 = 0xffff;  // 1
  char c2 = 0xfffff; // 2
  byte b1 = 0xffff;  // 3
  byte b2 = 0x7f;    // 4
  byte b3 = 0xff;    // 5
  byte b4 = -0x80;   // 6
}

Compile-time errors are generated at which lines?

a. 1
b. 2
c. 3
d. 4
e. 5
f. 6

Question 7

class EBH013 {
  public static void main (String[] args) {
    byte x = 3, y = 5;
    System.out.print((~x == -x - 1)+","+(~y == -y - 1));
}}

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. Run-time error
f. Compile-time error
g. None of the above

Question 8

class GFC500 {private String name;}
class GFC501 {
  private String name;
  private void setName(String name) {this.name = name;}
  private String getName() {return name;}
}
class GFC502 {
  private String name;
  public void setName(String name) {this.name = name;}
  public String getName() {return name;}
}

Which class is not tightly encapsulated?

a. GFC501
b. GFC502
c. GFC503
d. None of the above

Question 9

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 10

class SRC110 {
  public static void main (String[] args) {
    byte x1 = 0; byte x2 = 1;
    byte a1 = Math.min(x1,x2);  // 1
    int c1 = Math.min(0,1);     // 2
    long d1 = Math.min(0L,+1L); // 3
    System.out.print(a1+","+c1+","+d1);
}}

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

a. Prints: 0,0,0
b. Compile-time error at 1
c. Compile-time error at 2
d. Compile-time error at 3
e. Run-time error
f. None of the above

Question 11

class B {
  public static void main (String[] args) {
    byte b1 = 11;
    System.out.print(new Integer(b1).equals(new Integer(b1)) + ",");
    System.out.print(new Integer(b1).equals(new Short(b1)) + ",");
    System.out.print(new Integer(b1).equals(new Byte(b1)));
}}

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
i. Compile-time error
j. Run-time error
k. None of the above

Question 12

Which of the method invocation expressions would produce a run-time error?

a. Long.parseLong("-1")
b. Long.parseLong("+1")
c. Long.parseLong("01")
d. Long.parseLong("1L")
e. Long.parseLong("1.0")

Question 13

Which methods of the java.lang.Double class declare a parameter of type String?

a. doubleValue
b. floatValue
c. intValue
d. longValue
e. parseDouble
f. valueOf

Question 14

 •Stores key/value pairs.
 •Allows null elements, keys, and values.
 •Duplicate entries replace old entries.
 •Entries are not sorted.

Which of these classes provides the specified features?

a. LinkedList
b. TreeMap
c. TreeSet
d. HashMap
e. HashSet
f. Hashtable
g. None of the above

Question 15

import java.util.*;
class GFC107 {
  public static void main (String args[]) {
    Object a = new HashSet(), b = new HashMap();
    Object c = new Hashtable();
    System.out.print((a instanceof Cloneable)+",");
    System.out.print((b instanceof Cloneable)+",");
    System.out.print(c instanceof Cloneable);
}}

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
i. None of the above

Question 16

class A {
  int i1, i2;
  public void setI1(int i) {i1 = i;}
  public int getI1() {return i1;}
  public void setI2(int i) {i2 = i;}
  public int getI2() {return i2;}
  public A(int ii1, int ii2) {i1 = ii1; i2 = ii2;}
  public boolean equals(Object obj) {
    if (obj instanceof A) {
      return (i1 == ((A)obj).getI1()) & (i2 == ((A)obj).getI2());
    }
    return false;
  }
  public int hashCode() {
    // Insert statement here.
}}

If inserted at the specified location, which of the following statements would produce the most efficient hashCode method?

a. return 31;
b. return getI1();
c. return getI2();
d. return getI1() + getI2();
e. return 31 * getI1() + getI2();
f. None of the above

Question 17

class MWC207 {
  public static void main(String[] args) {
    int[][] a1 = {{1;2};{3;4;5};{6;7;8;9}};
    System.out.print(a1[0][1]+","+a1[1][2]+","+a1[2][3]);
}}

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

a. Prints: 14
b. Prints: 16
c. Prints: 1,5,9
d. Prints: 2,4,8
e. Prints: 2,5,9
f. Compile-time error
g. Run-time error
h. None of the above

Question 18

class Z {
  void m1() {
    static class F {}        // 1
    synchronized class G {}  // 2
    transient class H {}     // 3
    volatile class I {}      // 4
    abstract class A {}      // 5
    final class B {}         // 6
  }
}

Compile-time errors are generated at which lines?

a. 1
b. 2
c. 3
d. 4
e. 5
f. 6

Question 19

class JMM108 {
  static boolean b;
  public static void main(String[] args) {
    if (b) {System.out.print("A");
    } else if (b = false) {System.out.print("B");
    } else if (b) {System.out.print("C");
    } else if (!b) {System.out.print("D");
    } else {System.out.print("E");}
}}

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

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

Question 20

class ColorException extends Exception {}
class WhiteException extends ColorException {}
class White {
  void m1() throws ColorException {throw new ColorException();}
  void m2() throws WhiteException {throw new ColorException();}
  public static void main (String[] args) {
    White white = new White();
    int a,b,d,f; a = b = d = f = 0;
    try {white.m1(); a++;} catch (ColorException e) {b++;}
    try {white.m2(); d++;} catch (WhiteException e) {f++;}
    System.out.print(a+","+b+","+d+","+f);
}}

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

a. Prints: 0,1,0,0
b. Prints: 1,1,0,1
c. Prints: 0,1,0,1
d. Prints: 0,1,1,1
e. Prints: 1,1,1,1
f. Compile-time error
g. Run-time error
h. None of the above

Question 21


class D {
  private boolean b1, b2;
  public void setB1(boolean b) {b1 = b;}
  public void setB2(boolean b) {b2 = b;}
  public void m1 () {
    if (!b2 & !b1) {System.out.print("A");
    } else if (!b2 & b1) {System.out.print("B");
    } else if (b2 & !b1) {System.out.print("C");
    } else {assert false;}
  }
  public static void main (String[] args) {
    D d = new D();
    d.setB1(true); d.setB2(true);
    d.m1();
}}

Which statements are true?

a. With assertions enabled it prints an AssertionError message.
b. With assertions enabled it prints nothing.
c. With assertions disabled it prints an AssertionError message.
d. With assertions disabled it prints nothing.
e. An assertion should not be placed at any location that the programmer believes will never be reached under normal operating conditions.
f. The assert statement is being used to check a control-flow invariant to verify that the control flow never reaches a point in the program.

Question 22

class I {
  private String name;
  public String toString() {return name;}
  public I(String s) {name = s;}
}
class J {
  private static void m1(I[] a1) {a1 = null;}
  public static void main (String[] args) {
    I[] a1 = new I[3];   // 1
    a1[0] = new I("A");  // 2
    a1[1] = new I("B");  // 3
    a1[2] = new I("C");  // 4
    m1(a1);
    for (int i = 0; i < a1.length; i++) {
      System.out.print(a1[i]);
}}}

After method m1 returns, the object created on which line is eligible for garbage collection?

a. 1
b. 2
c. 3
d. 4
e. Compile-time error
f. Run-time error
g. None of the above

Question 23

class GFC211 {}  class GFC212 extends GFC211 {}
class GFC213 extends GFC212 {
  static void m(GFC211 x, GFC211 y) {System.out.print("GFC211,GFC211");}
  static void m(GFC211 x, GFC212 y) {System.out.print("GFC211,GFC212");}
  static void m(GFC212 x, GFC211 y) {System.out.print("GFC212,GFC211");}
  static void m(GFC212 x, GFC212 y) {System.out.print("GFC212,GFC212");}
  static void m(GFC211 x, GFC213 y) {System.out.print("GFC211,GFC213");}
  public static void main(String[] args) {
    GFC213 gfc213 = new GFC213(); m(gfc213, gfc213);
}}

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

a. Prints: GFC211,GFC211
b. Prints: GFC211,GFC212
c. Prints: GFC212,GFC211
d. Prints: GFC212,GFC212
e. Prints: GFC211,GFC213
f. Compile-time error
g. Run-time error
h. None of the above

Question 24


abstract class D {String s1 = "D"; String getS1() {return s1;}}
class E extends D {String s1 = "E"; String getS1() {return s1;}}
class F {
  public static void main (String[] s) {
    D x = new E(); System.out.print(x.s1 + x.getS1());
}}

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

a. Prints: DD
b. Prints: DE
c. Prints: ED
d. Prints: EE
e. Run-time error
f. Compile-time error
g. None of the above

Question 25

class Outer {
  static class StaticNested {
    static final int a = 25; // 1
    static final int b;      // 2
    static int c;            // 3
    int d;                   // 4
    static {b = 42;}         // 5
  }
  class NonStaticInner {
    static final int e = 25; // 6
    static final int f;      // 7
    static int g;            // 8
    int h;                   // 9
    static {f = 42;}         // 10
}}

Compile-time errors are generated at which lines?

a. 1
b. 2
c. 3
d. 4
e. 5
f. 6
g. 7
h. 8
i. 9
j. 10

Question 26

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 a1 = new A(); B b1 = new B(); C c1 = new C(); C c2 = new A();
    c2.m1(a1); c2.m1(b1); c2.m1(c1);
}}

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

a. Prints: AAA
b. Prints: ABC
c. Prints: CCC
d. Compile-time error
e. Run-time error
f. None of the above

Question 27

Which kind of variable would you prefer to synchronize on?

a. A member variable of a primitive type
b. A member variable that is an object reference
c. A method local variable that is a reference to an instance that is created within the method
d. None of the above

Question 28

class EBH108 {
  public static void main(String s[]) {
    int i=0, j = ++i + ((++i * ++i) % ++i) + ++i;
    System.out.print(j%5);
}}

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

a. Prints: 1
b. Prints: 2
c. Prints: 3
d. Prints: 4
e. Prints: 5
f. Run-time error
g. Compile-time error
h. None of the above
Copyright © 2002-2004, Dan Chisholm
All rights reserved.