Dan Chisholm's
Java Programmer Certification Mock Exam

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Question 1

class JSC102 {
  public static void main (String[] args) {
    private int x = 1; protected int y = 2; public int z = 3;
    System.out.println(x+y+z);
}}

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

Question 2

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

Question 3

class MCZ31 {
  public static void main (String[] args) {
    char a = '\t';  // 1
    char b = '\\';  // 2
    char c = '\"';  // 3
    char d = '\'';  // 4
    char e = '\?';  // 5 
}}

A compile-time error is generated at which line?

Question 4

Which of the following methods are static members of the java.lang.Double class?

Question 5

class D {
  public static void main (String[] args) {
    Boolean b1 = Boolean.valueOf("trUE");           // 1
    Boolean b2 = Boolean.valueOf("Even more true"); // 2
    Boolean b3 = Boolean.valueOf(null);             // 3
    System.out.print((b1==b2) + ",");
    System.out.print((b2==b3) + ",");
    System.out.println(b3==b1);
}}

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

Question 6

class E {
  static String m(float f) {return "f";}
  static String m(Float f) {return "F";}
  public static void main (String[] args) {
    System.out.print(m(Float.parseFloat("1")));
    System.out.print(m(Float.floatValue()));
    System.out.print(m(Float.valueOf("1")));
}}

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

Question 7

class E {
  static String m(short s) {return "p";}
  static String m(Short s) {return "S";}
  public static void main (String[] args) {
    Short s1 = new Short("1");
    System.out.print(m(s1.shortValue())+",");
    System.out.print(m(Short.parseShort("1"))+",");
    System.out.print(m(Short.valueOf("1")));
}}

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

Question 8

Which of these classes provides the specified features?

Question 9

import java.util.*;
class GFC104 {
  public static void main (String args[]) {
    LinkedList a1 = new LinkedList();
    ArrayList b1 = new ArrayList();
    Vector c1 = new Vector();
    System.out.print((a1 instanceof List)+",");
    System.out.print((b1 instanceof List)+",");
    System.out.print(c1 instanceof List);
}}

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

Question 10

class B {
  private int i1;
  public int hashCode() {return 1;}
}
class C {
  private int i1;
  public int hashCode() {return -1;}
}
class D {
  private int i1;
  public int hashCode() {return i1;}
}

Suppose that the equals method of classes B, C and D all make use of the value of the int variable, i1. Which class has a hashCode method that is not consistent with the hash code contract?

Question 11

Which of the following statements are true?

Question 12

abstract class A {}   // 1
transient class G {}  // 2
private class C {}    // 3
static class E {}     // 4

Suppose these are top-level class declarations and not nested class declarations. Which of these declarations would not produce a compile-time error?

Question 13

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

Which class declaration results in a compile-time error?

Question 14

class Level1Exception extends Exception {}
class Level2Exception extends Level1Exception {}
class Level3Exception extends Level2Exception {}
class Purple {
  public static void main(String args[]) {
    int a,b,c,d,f,g,x;
    a = b = c = d = f = g = 0;
    x = 4;
    try {
      try {
	switch (x) {
          case 1: throw new Level1Exception();
          case 2: throw new Level2Exception();
          case 3: throw new Level3Exception();
          case 4: throw new Exception();
      } a++; }
      catch (Level2Exception e) {b++;}
      finally{c++;}
    }
    catch (Level1Exception e) { d++;}
    catch (Exception e) {f++;}
    finally {g++;}
    System.out.print(a+","+b+","+c+","+d+","+f+","+g);
}}

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

Question 15

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 16

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

Question 17

class EBH011 {
  public static void main (String[] args) {
    float a = Float.POSITIVE_INFINITY;
    double b = Double.POSITIVE_INFINITY;
    double c = Double.NaN;
    System.out.print((a == b)+","+(c == c)+","+(c != c));
}}

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

Question 18

class A {
  public static void main(String[] args) {
    char a = 'a', b = 'b'; // 'a' = 97, 'b' = 98
    System.out.print(a + b + "" + a + b);
}}

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

Question 19

abstract class A {
  private int x = 4, y = 2;
  public int x() {return x;}
  public void x(int x) {this.x = x;}
  public int y() {return y;}
  public void y(int y) {this.y = y;}
  public abstract int math();
}
class B {
  static A a1 = new A(2,1) {
    public A(int i1, int i2) {x(i1);y(i2);};
    public int math() {return x()+y();}
  };
  public static void main(String[] args) {
    System.out.print(a1.math());
}}

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

Question 20

class JMM105 {
  public static void main(String args[]) {
    int x = 6; int success = 0;
    do  {
      switch(x) {
        case 0: System.out.print("0"); x += 5; break;
        case 1: System.out.print("1"); x += 3; break;
        case 2: System.out.print("2"); x += 1; break;
        case 3: System.out.print("3"); success++; break;
        case 4: System.out.print("4"); x -= 1; break;
        case 5: System.out.print("5"); x -= 4; break;
        case 6: System.out.print("6"); x -= 5; break;
      }
    } while ((x != 3) || (success < 2));
}}

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

Question 21

class C {
  String m1(int i) {
    switch (i) {
      case 0: return "A";
      case 1: return "B";
      case 2: return "C";
      default:
        assert false;
    }
    return "E";
  }
  public static void main(String[] args) {
    C c = new C();
    for (int i = 0; i < 4; i++) {
      System.out.print(c.m1(i));
}}}

Which statements are true?

Question 22

class I {
  private String name;
  public I(String s) {name = s;}
  private I other;
  public void other(I i) {other = i;}
}
class J {
  private I i1 = new I("A"), i2 = new I("B"), i3 = new I("C");
  private void m1() {
    i1.other(i2); i2.other(i1); i3.other(i3);
    i1 = i3; i2 = i3;
    m2();
  }
  private void m2() {/* Do amazing things. */}
  public static void main (String[] args) {
    new J().m1();
}}

Which of the three objects, A, B or C, is not eligible for garbage collection when method m2 begins to execute?

Question 23

class GFM16 {
  static int m1 (int i1, int i2) {
    int i3;
    if (i1 > 0) {i3 = i1 + i2;}
    return i3;
  }
  public static void main(String[] args) {
    System.out.println(m1(1,2));
}}

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

Question 24

class UltraViolet {
  public static void main (String[] args) {
    char a = '\u002a', b = '\u0024'; // a = Asterisk *; b = Dollar Sign $
    System.out.print(a + b);           // 1
    System.out.print(" ABC" + a + b);  // 2
}}

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

Question 25

class GFC202 {}  class GFC203 extends GFC202 {}
class GFC204 {
  static void m(GFC202 x) {System.out.print("GFC202");}
  static void m(GFC203 x) {System.out.print("GFC203");}
  public static void main(String[] args) {m(null);}
}

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

Question 26

class MWC206 {
  public static void main (String[] args) {
    int[][] a1 = {{1,2,3},{4,5,6},{7,8,9}};
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        System.out.print(a1[j][i]);
}}}}

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

Question 27

class EBH106 {
  public static void main(String args[]) {
    int a = 1; a += ++a + a++; System.out.print(a);
}}

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

Question 28

class Amber {
  public static void main(String[] args) {
    int[][] a = {{1,2},{0,1,2},{-1,0,2}};  // 1
    Object[] obj = (Object[])a.clone();    // 2
    for(int i = 0; i < obj.length; i++) {  // 3
      int[] ia = (int[])obj[i];            // 4
      System.out.print(ia[i]);             // 5
}}}

A compile-time error is generated at which line?

Question 29

class GFC307 {
  static void m1(int[] i1, int[] i2) {
    i1 = i2 = null;
  }
  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?