CS365 Midterm -- Spring 2021

1. ____________________ The type of component used to create a Java window.

2. ____________________ The type of widget I should use to allow the user to select a state/territory in the United States. There are roughly 50 states/territories in the US.

3. ____________________ The type of widget to use when I want the user to enter a social security number with 3 digits, then a dash, then 2 digits, then a dash, and finally 4 digits.

4. ____________________ The type of widget I should use to show a matrix of data with the rows representing a person and the columns representing information about the person, such as age, salary, name, etc.

5. ____________________ The type of widget to use if I want to convey a piece of information that should not be altered, such as instructions for entering some piece of data.

package       extends      import            virtual method
interface     type         namespaces        generic
class         finally      final             subtype
public        Scanner      void              void *
protected     subclasses   static            generational collector
composition   inheritance  iterator          stop-and-copy collector
Error         Throwable    Exception         RuntimeException
IOException   event        interrupt         non-virtual method
implements    classpath    include           hotspot compilation
import        try          throw             reference counting
catch         friends      polymorphism      mark-and-sweep collector
Object        union        vtable            setjmp/longjmp

1. C++ uses _______________________ and ____________________ to implement modules.
2. __________________ C uses this type to implement generic types.
3. __________________ How virtual methods are implemented by the compiler.
4. __________________ The ability of the same code to perform the same action on different types of data.
5. __________________ A type of garbage collector that explicitly counts the number of pointers to an object so that it can be garbage-collected when there are no longer any pointers to it.

Interior nodes are operator nodes, such as +, -, cos, and unary -, and their children may be either operator or operand nodes. Leaf nodes are operand nodes. All nodes contain a variable named value of type double, that is the result of their last evaluation. All nodes also contain a parent pointer to their parent (a parent node is always an Operator node). Operator nodes contain pointers to their children and a boolean variable named upToDate which indicates if their value is up-to-date. There are three types of operator nodes: single operand operators, such as cos and unary -, binary operand operators, such as +, -, *, and /, and n-ary operand operator nodes that can have arbitrarily many operands (remember that operands may be either operator or operand nodes). All nodes have an Evaluate() method that evaluates its operands and returns a double. For example, the Evaluate() method for plus might look like:

double Evaluate() {	      
  value = child1.getValue() + child2.getValue();
  return value;
}

void markCacheInvalid() {
  upToDate = false;
  if (parent != null) { parent.markCacheInvalid(); }
}

double getValue() {
  if (!upToDate) {
    Evaluate();
    upToDate = true;
  } 
  return value;
}

Finally an n-ary operator has two methods named addParameter and removeParameter that add/remove a child from its children list.

Write the Java code required to create this set of classes. You will need to create one or more additional superclasses that factor out common variables/methods. I want to see:

1. Class declarations, variable declarations, and method declarations. Do not provide method bodies, except for constructors. I do want to see your constructor bodies. Make sure that any classes and methods that you want to be abstract are declared as abstract and that non-virtual methods are appropriately declared.
2. Declare PlusOperator as a specific concrete class for a Binary operator. Do not worry about concrete classes for either Unary or n-ary operators and as with the other classes you create, do not provide method bodies, except for the constructor.
3. Here is a checklist of instance variables and methods that you need to place with the appropriate class(es):
   1. Instance variables: parent, value, upToDate, appropriate children variables that point to children
   2. Methods: Evaluate, markCacheInvalid, GetValue, SetValue, addParameter, removeParameter, and constructors (constructors for unary operators take a single node, constructors for binary operators take two nodes, constructors for n-ary operators take an ArrayList of nodes, and constructors for operands take a double, which is their value).

1. Write the java command required to execute Appointment. This command must work regardless of what directory you are in (i.e., you may not assume you are either in the parent directories for your packages or the package directories themselves).

2. Write the jar command required to jar up Appointment and allow the jar file to execute. The jar file should be named Appointment.jar.

1. Instance variables: It has two Lists named bag1 and bag2, each of which stores one of the two types.
2. Methods
   1. Something that assigns ArrayLists to bag1 and bag2 when a new Bag object is created. There are multiple ways this might be done, including via a constructor but there are other ways as well.
   2. An add method that takes two parameters of type T1 and T2 and adds the values to their respective lists.
   3. A find method that takes a parameter of type T1 and returns null if the parameter is not found and the corresponding type T2 value if the parameter is found (i.e., if it finds the T1 value at index 5 then it returns the T2 value at index 5 in T2's list). Make sure that you perform a deep rather than a shallow comparison when finding if the parameter exists.

1. The input consists of lines of the form:

   voterName candidate1 candidate2 ... candidaten
   

   Each name is a single word. There must be at least one candidate and there may be as many candidates as the voter wants to list. Do not worry about repeated candidate names.
2. If a voter tries to vote a second time, throw a RepeatVoterException with the voter's name. Catch the exception and print the error message "voter xxxx has already voted" where xxxx is the name of the voter.
3. If the ballot does not contain a voterName and at least one candidate name, then print the error message ""ballot xxxx: must have at least one voter and one candidate" where xxxx is the contents of the line containing the missing voterName/candidateName. You are not allowed to use an if statement to check if the voter and candidate names are present. Instead you must read through the line as though the voter/candidate name is present and catch a NoSuchElementElement exception if the names are absent.

brad yifan joe
sarah
nels yifan frank sam
sandy yifan joe brad smiley
nels brad
    

ballot sarah: must have at least one voter and one candidate
voter nels has already voted
frank 1
brad 1
sam 1
smiley 1
joe 2
yifan 3

Efficiency matters!!! If you use inefficient data structures or inefficient methods for sorting you will lose points.

Here is the beginning of the class. Please note that I have written main and the RepeatVoterException classes for you:

import java.util.*;

class Vote {
    public class RepeatVoterException extends Exception {
	public String voterName;
	
	public RepeatVoterException(String name) {
	    voterName = name;
	}
    }

    public static void main(String args[]) {
	new Vote();
    }