Certified Java Programmer Mock Exam

Question 1

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

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?

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?

Question 4

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 5

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 6

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?

Question 7

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

Question 8

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?

Question 9

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?

Question 10

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?

Question 11

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 12

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?

Question 13

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?

Question 14

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

Question 15

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

Question 16

Which of these classes provides the specified features?

Question 17

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?

Question 18

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 19

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?

Question 20

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?

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?

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?

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?

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?

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?

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?

Question 27

Which kind of variable would you prefer to synchronize on?

Question 28

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

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