Certified Java Programmer Mock Exam

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 {
  private int[] val;
  private int hash;
  public int hashCode() {
    int h = hash;
    if (h == 0) {
      int len = val.length;
      for (int i = 0; i < len; i++) {
        h = 31*h + val[i];
      }
      hash = h;
    }
    return h;
  }
  // The equals method has been omitted for clarity.
  A (int[] val) {this.val = (int[])val.clone();}
  public static void main (String[] args) {
    A a = new A(new int[]{1,2,3});
    System.out.print(a.hashCode());
}}

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

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 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 20

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 21

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 22

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 23

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 24

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 25

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 26

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 27

abstract class A {
  private int x = 4;
  private int 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 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?