Dan Chisholm's
Java Programmer Certification Mock Exam

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Question 1

class MCZ13 {
  public static void main (String[] args) {
    String s = null;
    System.out.print(s);
}}

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

Question 2

Suppose that an interface, I1, is not a member of an enclosing class or interface. Which of the following modifiers can be applied to interface I1?

Question 3

Which of the following represent the full range of type char?

Question 4

class EBH012 {
  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?

Question 5

class Black {
  public static void main(String[] args) {
    short s1 = 1;        //1
    char c1 = 1;         //2
    byte b1 = s1;        //3
    byte b2 = c1;        //4
    final short s2 = 1;  //5
    final char c2 = 1;   //6
    byte b3 = s2;        //7
    byte b4 = c2;        //8
}}

Compile-time errors are generated at which lines?

Question 6

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

Question 7

Which of the following is a checked exception?

Question 8

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 9

class SRC109 {
  public static void main (String[] args) {
    short x3 = 0; short x4 = 1;
    short b1 = Math.min(x3,x4); // 1
    int c1 = Math.min(0,1);     // 2
    long d1 = Math.min(0L,+1L); // 3
    System.out.print(b1+","+c1+","+d1);
}}

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

Question 10

class C {
  public static void main (String args[]) {
    String s1 = "1", s2 = "2";
    Byte b1 = Byte.parseByte(s1);
    Byte b2 = Byte.parseByte(s2);
    System.out.print(b1.byteValue() + b2.byteValue());
}}

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

Question 11

class A {
  public static void main (String[] args) {
    String s = "11";
    int i1 = Integer.parseInt(s);
    System.out.print(new Integer(i1).equals(new Integer(i1)) + ",");
    System.out.print(new Integer(i1).equals(new Integer(s))  + ",");
    System.out.print(new Integer(i1) == new Integer(i1));
}}

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

Question 12

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

Question 13

Which method of the java.lang.Double class returns an instance of type Double?

Question 14

Which of these classes provides the specified features?

Question 15

import java.util.*;
class GFC106 {
  public static void main (String args[]) {
    Object a = new HashSet(), b = new HashMap();
    Object c = new Hashtable();
    System.out.print((a instanceof Map)+",");
    System.out.print((b instanceof Map)+",");
    System.out.print(c instanceof Map);
}}

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

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());
    }
    return false;
  }
  public int hashCode() {
    // Insert statement here.
}}

Which of the following statements could be inserted at the specified location without violating the hash code contract?

Question 17

class JSC104{
  public float a;        // 1
  protected float b;     // 2
  private float c;       // 3
  static float d;        // 4
  synchronized float i;  // 5
}

A compile-time error is generated at which line?

Question 18

class Z {
  void m1() {
    abstract class A {}      // 1
    final class B {}         // 2
    private class C {}       // 3
    protected class D {}     // 4
    public class E {}        // 5
  }
}

Which class declarations result in compile-time errors?

Question 19

class JMM107 {
  public static void main(String[] args) {
    boolean b = true;
    if (b = false) {System.out.print("A");
    } else if (b) {System.out.print("B");
    } else {System.out.print("C");}
}}

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

Question 20

class GFM17 {
  int x;                                    // 1
  public static void main(String[] args) {  // 2
    int y = 0;                              // 3
    System.out.print(x+",");                // 4
    System.out.print(y);                    // 5
}}

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

Question 21

class GFC205 {}  class GFC206 extends GFC205 {}
class GFC207 extends GFC206 {
  static void m(GFC205 x, GFC205 y) {System.out.print("GFC205,GFC205");}
  static void m(GFC205 x, GFC206 y) {System.out.print("GFC205,GFC206");}
  static void m(GFC206 x, GFC205 y) {System.out.print("GFC206,GFC205");}
  static void m(GFC206 x, GFC206 y) {System.out.print("GFC206,GFC206");}
  public static void main(String[] args) {
    GFC207 gfc207 = new GFC207(); m(gfc207, gfc207);
}}

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

Question 22

interface I {String s1 = "I";}
class A implements I {String s1 = "A";}
class B extends A {String s1 = "B";}
class C extends B {
  String s1 = "C";
  void printIt() {
    System.out.print(((A)this).s1 + ((B)this).s1 +
                     ((C)this).s1 + ((I)this).s1);
  }
  public static void main (String[] args) {new C().printIt();}
}

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

Question 23

class G {
  final String s1 = "G.s1";
  class Z {
    String s1;
    void m1() {System.out.println(???);}
  }
  public static void main(String args[]) {
    G g = new G(); g.new Z().m1();
}}

Which name or expression could be used in place of ??? to cause the program to print "G.s1"?

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

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

Question 25

class A {
  private static int f1 = 1;
  private int f2 = 2;
  void m1(int p1, final int p2) {
    int l1 = 5;
    final int l2 = 6;
    Object x = new Object() {
      int a = f1;  // 1
      int b = f2;  // 2
      int c = p1;  // 3
      int d = p2;  // 4
      int e = l1;  // 5
      int f = l2;  // 6
};}}

Compile-time errors are generated at which lines?

Question 26

class EBH107 {
  static int m(int i) {System.out.print(i + ","); return i;}
  public static void main(String s[]) {
    int i=0, j = m(++i) + m(++i) * m(++i) % m(++i) + m(++i);
    System.out.print(j%5);
}}

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

Question 27

class GFC308 {
  int[] i1 = {1}, i2 = {3};
  void m1() {
    m2(i1, i2);
    System.out.print(i1[0] + "," + i2[0]);
  }
  void m2(int[] i1, int[] i2) {
    int[] i3 = i1;
    this.i1 = i2;
    this.i2 = i3;
  }
  public static void main (String[] args) {
    new GFC308().m1();
}}

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

Question 28

class A13 {}
class A14 {
  public static void main(String[] arg) {
    A13[]     a1 = new A13[1];         // 1
    A13[][]   a2 = new A13[2][1];      // 2
    A13[][][] a3 = new A13[3][3][3];   // 3
    System.out.print(a3[2][2][2]);     // 4
    a1[0] = new A13();                 // 5
    a2[0] = a2[1] = a1;                // 6
    a3[0] = a3[1] = a3[2] = a2;        // 7
    System.out.print(a3[2][2][2]);     // 8
}}

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