public class Tree {
	private String species;
	private double height;
	private int age;

	public Tree (String aTree, double newHeight, int newAge) {
		species = aTree;
		height = newHeight;
		age = newAge;
	}

	public String getSpecies() {
		return species;
	}

	public double getHeight() {
		return height;
	}

	public void getAge() {
		return age;
	}

	public void increaseAge(int numYears, double rateOfGrowth) {

		// to be completed as specified in the problem above
	}

	public void addHeighte(double amount) 
{
			height = height + amount;
		}

		public int compareTo(Tree other) 
		{
			// to be completed as specified in the problem above
}

public boolean equals(Tree other)
{

	return getSpecies().equals(other.getSpecies()) &&
			Math.abs(height - other.height) <= 12;
}

	public String toString() 
{
		return “Species: ” + species + 
				“ Height: ” + height;
	}
 
public class TreeList {
	private Tree[] list;
	private int numTrees;
	
	/**
	 	constructs an empty list of size 1
	 */
	public TreeList() {
	
		list = new Tree[1];
		numTrees = 0;
	}
	
	/**
		adds the specified Tree to the end of the list, after 
resizing if necessary
	*/
	public void addToEnd(Tree nextTree) {
		
		if (numTrees == list.length)
			resize();
		
		list[numTrees] = nextTree;
		numTrees++;
	}
	
	
/**
		returns the number of Trees in the list
	*/
	public int size() {
	
		return numTrees;
	}

	/**
	 	helper method to allow dynamic growth of the list, by doubling 
the capacity of the list and maintaining the current order
	 */
	private void resize() {
	
		Tree[] temp = new Tree[list.length * 2];
		
		for (int i = 0; i < size(); i++) {
			temp[i] = list[i];
		}
		
		list = temp;
	}
}

height = height + (Integer.doubleValue(newYears) * rateOfChange);

tree1.compareTo(tree2);

private int compareTo(Tree tree)
{

  if(this.species.equalsIgnoreCase(tree.species)) // where 'this' refers to tree1 // in my previous example 'tree1.compareTo(tree2);
  return -1;

  // etc...

}

tree1.compareTo(tree2);

int compareTo(Tree tree) // here your return type is integer, and you are
{                                 // passing a Tree object as your parameter.

if(this.getSpecies().equalsIgnoreCase(tree.getSpecies()))
return -1;

//in this if statement, notice the keyword 'this'.  if you look at the actual
//call of the function 'tree1.compareTo(tree2);' then you can clearly see
//that 'this' is refering to 'tree1'.

// the equalsIgnoreCase() method is a String method that see's if two
// string are alike, regardless the case.  For example: 'HEllO' and 'hello'.

// if this is too confusing, you can alway construct your compareTo() method
// like so:

// int compareTo(Tree tree1, Tree tree2)
// {
    
         // if(tree1.getSpecies().equalsIgnoreCase(tree2.getSpecies()))
         // return -1;

         // etc, etc... 

// }

}