1. ./Birthday.java
2. ./FinallyTest.java
3. ./ListIteratorTests.java

/**
 * Demonstrates use of throwing IllegalArgumentExceptions to prevent errors.
 * @author sprenkle
 */
public class Birthday {
	private int day;
	private int month;

	private static int[] DAYS_IN_MONTH = {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
	
	/**
	 * @param month
	 * @param day
	 */
	public Birthday(int month, int day) {
		super();
		this.day = day;
		this.month = month;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString() {
		StringBuilder builder = new StringBuilder();
		builder.append(month);
		builder.append("/");
		builder.append(day);
		return builder.toString();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.lang.Object#equals(java.lang.Object)
	 */
	@Override
	public boolean equals(Object obj) {
		return super.equals(obj);
	}

	/**
	 * This is a better way to implement setting the month and the day because
	 * they are related to (not independent of) each other.
	 * @param month
	 * @param day
	 */
	public void setBirthday(int month, int day) {
		if( month < 1 || month > 12) {
			throw new IllegalArgumentException("month must be between 1 and 12");
		}
		if( day < 1 || day > 31 ) {
			throw new IllegalArgumentException("day must be between 1 and 31");
		}
		
		/* The below code is clunky because we are handling the months in a big
		if. It would be better to have an array of days in month and check that
		to see if day is valid. */
		
		if( month == 2 && day > 29) {
			// handle Feb
			throw new IllegalArgumentException("February has only 29 days.");
		}
		if( month == 4 || month == 6 || month == 9 || month == 11 ) {
		    throw new IllegalArgumentException(month + " has only 29 days.");
		}
		
		// ALTERNATIVELY:
		// if( day > DAYS_IN_MONTH[month-1] )
		// throw new IllegalArgumentException ...
		
		// only set the month and day after we know that the month and day are valid.
		this.month = month;
		this.day = day;
	}
	
	/**
	 * @return the day
	 */
	public final int getDay() {
		return day;
	}

	/**
	 * 
	 * @param day
	 */
	public final void setDay(int day) {
		this.day = day;
	}

	/**
	 * @return the month
	 */
	public final int getMonth() {
		return month;
	}

	/**
	 * @param month
	 *            the month
	 */
	public final void setMonth(int month) {
		this.month = month;
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Birthday b = new Birthday(1, 1);
		System.out.println(b);
		// test calling the method with the exceptions:
		b.setBirthday(1,32); // should throw an exception
		b.setBirthday(2,30); // we'll never get to here because the last statement threw an exception
	}

}

/**
 * Example using finally block
 * 
 * @author Sara Sprenkle
 */
public class FinallyTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		try {
			System.out.println("In try");
			//throw new NullPointerException();
		} catch (Exception e) {
			System.out.println("In Catch");
		} finally {
			System.out.println("In Finally");
		}
	}

}

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class ListIteratorTests {

	/**
	 * Condition that we want for items in our list.
	 * 
	 * @param item
	 * @return
	 */
	public static boolean condition(int item) {
		return item % 2 == 0;
	}

	private static void displayList(List<Integer> myList, String string) {
		System.out.println(string);
		for (Integer i : myList) {
			System.out.println(i);
		}
	}

	public static void main(String[] args) {

		// set up a list
		List<Integer> myList = new ArrayList<>();
		for (int i = 0; i < 10; i++) {
			myList.add(i);
		}

		displayList(myList, "Original List:");
		System.out.println();

		Iterator<Integer> iter = myList.iterator();

		while (iter.hasNext()) {
			Integer item = iter.next();
			if (!condition(item)) {
				// alternatively, could mutate this object, if the object has
				// mutator methods available.
				// Can't replace this item or remove the item and add in a new
				// object.
				iter.remove();
			}
		}

		displayList(myList, "Final List:");

	}

}