Certified Java Programmer Mock Exam

Question 1

import java.util.*;
class A {
  private static int notFinalized;
  public static int notFinalized() {return notFinalized;}
  private static ArrayList finalizedNames = new ArrayList();
  public static Iterator finalizedNames() {
    return finalizedNames.iterator();
  }
  private String name;
  public A(String s) {name = s; notFinalized++;}
  public void finalize() {
    finalizedNames.add(name);
    notFinalized--;
  }
}
class F {
  public static void main(String[] args) {
    A x1 = new A("X");
    A y1 = new A("Y");
    x1= null;
    y1 = null;
    System.gc();
    while (A.notFinalized() > 0) {
      try {Thread.sleep(1000);} catch (InterruptedException ie) {}
    }
    Iterator i = A.finalizedNames();
    while (i.hasNext()) {
      System.out.print(i.next());
    }
  }
}

Which of the following are true statements and which of the following could be a result of attempting to compile and run the program?

Question 2

class J {
  private static int notFinalized;
  public static int notFinalized() {return notFinalized;}
  private K k;
  private int name;
  public int name() {return name;}
  public J(K k, int i) {this.k = k; name = i; notFinalized++;}
  public void finalize() {
    synchronized (k) {
      System.out.print(name);
      notFinalized--;
      k.notify();
    }
  }
}

class K {
  private void m1() {
    J j = null;
    for (int i = 0; i < 5; i++) {
      j = new J(this, i);       // 1
    }
    Runtime.getRuntime().gc();  // 2
    synchronized (this) {
      while (J.notFinalized() > 0) {
        try {wait();} catch (InterruptedException ie) {}
      }
    }
  }
  public static void main(String[] args) {
    new K().m1();
  }
}

When the processing of line 2 begins how many objects of type J that were created at line 1 are eligible for garbage collection?

Question 3

class Arnold {
  private H h;
  private String quote;
  public String quote() {return quote;}
  private static int notFinalized;
  public static int notFinalized() {return notFinalized;}
  public Arnold(H h, String s) {this.h = h; quote = s; notFinalized++;}
  public void finalize() {
    synchronized (h) {
      notFinalized--;
      h.arnold(this);
      h.notify();
    }
  }
}
class H {
  private Arnold arnold;
  public void arnold(Arnold a) {arnold = a;}
  public void m1() {
    arnold = new Arnold(this, "I'll be back!");
    arnold = null;
    System.gc();
    synchronized (this) {
      while (Arnold.notFinalized() > 0) {
        try {wait();} catch (InterruptedException ie) {}
      }
    }
    System.out.print(arnold.quote()); // 1
  }
  public static void main(String[] args) {new H().m1();}
}

Which of the following are true statements and which of the following could be a result of attempting to compile and run the program?

Question 4

class I {
  private static int notFinalized;
  public static int notFinalized() {return notFinalized;}
  private J observer;
  private I other;
  public void other(I i) {other = i;}
  private String name;
  public String name() {return name;}
  public I(String s, J j) {this (s, j, null);}
  public I(String s, J j, I i) {
    name = s;
    observer = j;
    other = i;
    notFinalized++;
  }
  public void finalize() {
    System.out.print(name);
    synchronized (observer) {
      notFinalized--;
      observer.notify();
    }
  }
}
class J {
  private void m1() {
    I i1 = new I("X", this);
    I i2 = new I("Y", this, i1);
    I i3 = new I("Z", this, i2);
    i1.other(i3);
    i3 = i2 = i1 = null;      // 1
    Runtime.getRuntime().gc();
    synchronized (this) {
      while (I.notFinalized() > 0) {
        try {wait();} catch (InterruptedException ie) {}
      }
    }
  }
  public static void main (String[] args) {
    new J().m1();
  }
}

Which of the following are true statements and which of the following could be a result of attempting to compile and run the program?

Question 5

class J {
  private static int finalized;
  public static int finalized() {return finalized;}
  private K k;
  private String name;
  public String name() {return name;}
  public J(K k, String s) {this.k = k; name = s;}
  public void finalize() {
    synchronized (k) {
      finalized++;
      k.j(this);
      k.notify();
    }
  }
}
class K {
  private J j1;
  public void j(J j) {j1 = j;}
  public void m1() {
    j1 = new J(this, "X");
    j1.finalize();
    j1.finalize();
    for (int i = 0; i < 3; i++) {
      int finalized = J.finalized();
      j1= null;
      System.gc();
      synchronized (this) {
        if (J.finalized() == finalized) {
          try {wait(1000);} catch (InterruptedException ie) {}
        }
      }
      if (j1 != null) {
        System.out.print(j1.name());
      }
    }
    System.out.print(J.finalized());
  }
  public static void main(String[] args) {new K().m1();}
}

Which of the following are true statements and which of the following could be a result of attempting to compile and run the program?

Question 6

import java.util.*;
class C {
  private Object observer;
  private static int notFinalized;
  public static int notFinalized() {return notFinalized;}
  private static ArrayList finalizedNames = new ArrayList();
  public static Iterator finalizedNames() {
    return finalizedNames.iterator();
  }
  private String name;
  public C(Object obs, String s) {observer = obs; name = s; notFinalized++;}
  public void finalize() {
    synchronized (observer) {
      finalizedNames.add(name);
      notFinalized--;
      observer.notify();
    }
  }
}
class G {
  public void m1() {
    C x1 = new C(this, "X");
    C y1 = new C(this, "Y");
    x1= null;
    y1 = null;
    System.gc();
    synchronized (this) {
      while (C.notFinalized() > 0) {
        try {wait();} catch (InterruptedException ie) {}
      }
    }
    Iterator i = C.finalizedNames();
    while (i.hasNext()) {
      System.out.print(i.next());
    }
  }

  public static void main(String[] args) {
	  new G().m1();
  }
}

Which of the following are true statements and which of the following could be a result of attempting to compile and run the program?

Question 7

class Arnold {
  private I i;
  private String quote;
  public String quote() {return quote;}
  private static int instances;
  public static int instances() {return instances;}
  public static void heIsBack() {instances++;}
  public Arnold(I i, String s) {this.i = i; quote = s; instances++;}
  public void finalize() {
    synchronized (i) {
      instances--;
      i.arnold(this);
      i.notify();
    }
  }
}
class I {
  private Arnold arnold;
  public void arnold(Arnold a) {arnold = a;}
  public void m1() {
    arnold = new Arnold(this, "I'll be back!");
    for (int i = 0; i < 3; i++) {
      arnold = null;
      System.gc();
      synchronized (this) {
        if (Arnold.instances() > 0) {
          try {wait(1000);} catch (InterruptedException ie) {}
        }
      }
      if (arnold != null) {
        Arnold.heIsBack();
        System.out.print(arnold.quote());
      }
    }
  }
  public static void main(String[] args) {new I().m1();}
}

Which of the following are true statements and which of the following could be a result of attempting to compile and run the program?