demosimpletreeuos.java

国外的数据结构与算法分析用书

/* DemoSimpleTreeUos.java
 * ---------------------------------------------
 * Copyright (c) 2002 University of Saskatchewan
 * All Rights Reserved
 * --------------------------------------------- */
package dslib.demo;

import dslib.tree.*;
import java.io.*;
import java.lang.reflect.*;

/**	 A class that demonstrates the use of any SimpleTreeUos */
public class DemoSimpleTreeUos
{
	/**  A demo for testing SimpleTreeUos. 
		@param t The tree that will be demo-ed.*/
	public DemoSimpleTreeUos(LinkedSimpleTreeUos t)
	{	
		// place the output in a text file that reflects the class being demonstrated.
		String className = t.getClass().getName();
		className = className.substring(className.lastIndexOf(".")+1);
		PrintWriter out = null;
		try
		{
			out = new PrintWriter(new FileOutputStream("OutputDemo" + className + ".txt", true));
		} catch (Exception e)
		{
			System.err.println("Error creating output file in test routine for " + className);
			e.printStackTrace();
		}
		out.println("Testing routines of SimpleTreeUos");
		out.println("inserted 3, 6, 10");
		out.println("inserted 2, 4, 9, 11");
		t = createInstance(t, new Integer(6));
		LinkedSimpleTreeUos t1 = createInstance(t, new Integer(2));
		LinkedSimpleTreeUos t2 = createInstance(t, new Integer(3));
		LinkedSimpleTreeUos t3 = createInstance(t, new Integer(4));
		LinkedSimpleTreeUos t4 = createInstance(t, new Integer(7));
		LinkedSimpleTreeUos t5 = createInstance(t, new Integer(10));
		LinkedSimpleTreeUos t6 = createInstance(t, new Integer(11));
		t.setRootLeftSubtree(t2);
		t2.setRootLeftSubtree(t1);
		t2.setRootRightSubtree(t3);
		t.setRootRightSubtree(t5);
		t5.setRootLeftSubtree(t4);
		t5.setRootRightSubtree(t6);
		out.println("Root value? " + t.rootItem());
		out.println("Left value? " + t.rootLeftSubtree().rootItem());
		out.println("Right value? " + t.rootRightSubtree().rootItem());
		out.println("Left Left value? " + t.rootLeftSubtree().rootLeftSubtree().rootItem());
		out.println("Right Left value? " + t.rootLeftSubtree().rootRightSubtree().rootItem());
		out.println("Left Right value? " + t.rootRightSubtree().rootLeftSubtree().rootItem());
		out.println("Right Right value? " + t.rootRightSubtree().rootRightSubtree().rootItem());
		out.println("That's it.");
		t.wipeOut();
		out.close();
	}
	
	/** creates a new instance of type l with initial value o 
		@param l an instance of a tree
		@param o an initial value*/
	protected LinkedSimpleTreeUos createInstance(LinkedSimpleTreeUos l, Object o)
	{
		/* this method uses a few aspects of the Java Language that have not been discussed
		in the text.  In a nutshell, this class creates a new instance of whatever
		type of tree it is passed with a inital value of o.  It does this by
		finding all of the constructors of the class and selecting the one that 
		it requires.*/
		try
		{
			Object[] args = {null, o, null};
			Constructor[] con = l.getClass().getConstructors();
			for(int i =0 ; i <= con.length -1; i++)
				if(con[i].getParameterTypes().length == 3)
					return (LinkedSimpleTreeUos) con[i].newInstance(args );
		} catch (Exception e)
		{
			System.out.println("Error in instance creation!!");
		}
		return null;
	}
}