Thread: Splitting text into several components

I have already explained how to make a TreeMap sort in reverse Integer order. Read the API doc for TreeMap, use the constructor with the Comparator in it and write a Comparator that does what you want. It's much easier than the quantity of documentation would have you believe.

If you're not using some legacy Java, or some Java that has been written for the sole purpose of annoying you, you shouldn't be casting any references. If you do find yourself believing it necessary, you should fix your code where you went wrong so you don't have to do it.

Your TreeMap<Integer, Integer> should be *inside* your Polynomial class. Every time you matcher.find() a term in the input string, you should thePoly.add(coeff, exp) - that method will put two Integers into the TreeMap. When you've exhausted your input string, print thePoly and it will magically look right because you'll have a toString() method like:

@Override
public String toString()
{
  StringBuilder sb = new StringBuilder();
  /* terms magically in correct order, thanks to TreeMap */
  for (Map.Entry<Integer/*exp*/, Integer/*coeff*/> entry : MAP.entrySet())
  {
     /* style each term */
  }
  return sb.toString(); 
}

Originally Posted by snowguy13

You're welcome! So, I'm curious, what is the extent of this program's functionality? How much and what will it do when it's done?

Well basically it takes 2 polynomials of the nth degree, and is capable of adding, subtracting, multiplying and dividing them; then returning the result in canonical form.

I've gotten about everything working except, multiplication (im sort of stuck on this for now) and division (which once i implement multiplication, will be simple as it's just the inverse). It also doesnt simplify the users input correctly yet either, like: -12x^5+6x^3-3x+5 + 1 does NOT simplify into -12x^5+6x^3-3x+6 shouldnt be too hard to get working though.

if you like, you can go ahead and give it a spin. it even has a gui now lol.

package project2;
 
import java.awt.Color;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
 
//polynomial class
class Polynomial
{
	Node head;	
 
	Polynomial()
	{
		head = null;
	}
 
	//insert Node
	public void add(int coef, int power)
	{
 
		Node temp = new Node(coef, power, null);		
 
		if (head == null)
		{
			head = temp;			
		}
		else {			
			Node p = null;
			Node q = head;
			//insert in front if exponent is higher
			if (temp.getElement2() > q.getElement2())
			{				
				temp.setNext(head);
				head = temp;				
			} 
			else 
			{
				//insert at middle or end				
				while ( q != null && q.getElement2() > temp.getElement2())
				{				
					p = q;
					q = q.getNext();
				}
				p.setNext(temp);
				temp.setNext(q);				
			}
		}
 
	}
 
//add 2 polynomials together
	public Polynomial addPoly(Polynomial poly1, Polynomial poly2){
		Polynomial tempPoly = new Polynomial();
 
		int power = (poly1.head.getElement2() > poly2.head.getElement2()) ? poly1.head.getElement2() : poly2.head.getElement2();
 
		while (power >=0){
			Node n1 = poly1.head;
			while (n1 != null){
				if (n1.getElement2() == power)
				break;
				n1 = n1.getNext();
			}
 
			Node n2 = poly2.head;
			while (n2 != null){
				if (n2.getElement2() == power)
				break;
				n2 = n2.getNext();
			}
 
			if((n1 != null) && (n2 != null))
				tempPoly.add((n1.getElement1() + n2.getElement1()), n1.getElement2());
			else if (n1 != null)
				tempPoly.add(n1.getElement1(), n1.getElement2());
			else if (n2 != null)
				tempPoly.add(n2.getElement1(), n2.getElement2());
			power--;
		}
		return tempPoly;
	}
//Subtract 2 polynomials
	public Polynomial subPoly(Polynomial poly1, Polynomial poly2){
		Polynomial tempPoly = new Polynomial();			
 
 
		int power = (poly1.head.getElement2() > poly2.head.getElement2()) ? poly1.head.getElement2() : poly2.head.getElement2();
 
		while (power >=0){
			Node n1 = poly1.head;
			while (n1 != null){
				if (n1.getElement2() == power)
				break;
				n1 = n1.getNext();
			}
 
			Node n2 = poly2.head;
			while (n2 != null){
				if (n2.getElement2() == power)
				break;
				n2 = n2.getNext();
			}
 
			if((n1 != null) && (n2 != null))
				tempPoly.add((n1.getElement1() + (n2.getElement1()* -1)), n1.getElement2());
			else if (n1 != null)
				tempPoly.add(n1.getElement1(), n1.getElement2());
			else if (n2 != null)
				tempPoly.add(n2.getElement1()* -1, n2.getElement2());
			power--;
		}
		return tempPoly;
	}
 
//Multiply 2 polynomials - not working
 
	/*public Polynomial multPoly(Polynomial poly1, Polynomial poly2)
	{
 
	int coef;
	int power;
 
	Polynomial poly3 = new Polynomial();
 
	Node n1 = poly1.head;
	Node n2 = poly2.head;
 
	while ( poly1 != null )
	            {
 
		while ( poly2 != null )
	                {
	                    coef = n1.Element1 * n2.Element1;
	                    power = poly1.head.Element1 + poly2.head.Element1;
 
	                    System.out.println(coef);
	                    System.out.println(power);
 
	                    n2 = n2.getNext();
 
 
 
	                    poly3.add(coef, power) ;
	                }
 
	               n2 = poly2.head;  
 
	                n1 = n1.getNext() ;  
	            }
 
	return poly3;
 
	}*/
 
	//Prepare the string using regular expression
	public Polynomial prep(String s)
	{
 
		Polynomial poly = new Polynomial();
 
		s= s.replaceAll("\\s+", "");
 
		String str1 = "(-?[0-9]{1,})x\\^(-?[0-9]{1,})?";
		String str2 = "(-?[0-9]{1,})x";
		String str3 = "(-?[0-9]{1,})";
		Pattern p = Pattern.compile(str1);
		Pattern p2 = Pattern.compile(str2);
		Pattern p3 = Pattern.compile(str3);
 
		Matcher matcher = p.matcher(s);
		Matcher matcher2 = p2.matcher(s);
		Matcher matcher3 = p3.matcher(s);
		int coef;
		int exp;
 
		int index = 0;
		boolean matchFound;				 
		do{
			if(matchFound = matcher.find(index))
			{
 
				coef = Integer.parseInt(matcher.group(1));
				exp = Integer.parseInt(matcher.group(2));  
 
			    poly.add(coef,exp);
 
				index = matcher.end();
			}
			else if (matchFound = matcher2.find(index))
			{
				String groupStr = matcher2.group(1);				
				poly.add(Integer.parseInt(matcher2.group(1)),1);
 
				index = matcher2.end();
			}
			else if (matchFound = matcher3.find(index))
			{
				String groupStr = matcher3.group(1);				
				poly.add(Integer.parseInt(matcher3.group(1)),0);
 
				index = matcher3.end();
			}
			else
				matchFound = false;
 
		}while(matchFound);		
 
		return poly;
 
	}
 
	//to string	
	public String toString()
	{
		Node current = head.getNext();
		String output = "";
		if(head != null)
		{
			if(head.Element1 == 0)
			{
 
			}
			else if (head.Element2 == 0)
			{
				output += head.Element1;
			}
			else if (head.Element2 == 1)
			{
				output += head.Element1 + "x";
			}
			else
			{
				output += head.Element1 + "x^" + head.Element2;
			}
 
		}
		while(current != null)
		{
			if(current.Element1 == 0)
			{
 
			}
			else if (current.Element2 == 0)
			{
				if (current.Element1 > 0)
				{
					output += "+" + current.Element1;
				}
				else
					output += current.Element1;
			}
			else if (current.Element2 == 1)
			{
				if (current.Element1 > 0)
				{
					output += "+" + current.Element1 + "x";
				}
				else					
					output += current.Element1 + "x";
			}
			else if (current.Element1 > 0)
			{
				output += "+" + current.Element1 + "x^" + current.Element2;
			}
			else
			{
				output += current.Element1 + "x^" + current.Element2;
			}
			current = current.getNext();
		}
		return output;
	}
 
//node class
	class Node
	{
		int Element1, Element2;
		Node next;
 
		public Node(int Element1,int Element2)
		{			
			this.Element1 = Element1;			
			this.Element2 = Element2;
			next = null;
		}
 
		public Node(int Element1, int Element2, Node n) 
		{
			this.Element1 = Element1;
			this.Element2 = Element2;
			next = n;
		}
 
		public Node getNext()
		{
			return next;
		}
 
		public void setNext(Node next)
		{
			this.next = next;
		}
 
		public int getElement1() {
			return Element1;
		}
 
		public void setElement1(int element1) {
			Element1 = element1;
		}
 
		public int getElement2() {
			return Element2;
		}
 
		public void setElement2(int element2) {
			Element2 = element2;
		}		
	}
}
 
//GUI
class MainWindow extends JFrame
{
	JTextField jPoly1;
	JTextField jPoly2;
	JTextArea jResult;
	JButton jAdd;
	JButton jSub;
	JButton jMult;
	JButton jDiv;
	JButton jExit;
 
 
 
 
	MainWindow()
	{
		JPanel p1 = new JPanel();		
		JPanel p2 = new JPanel();
		JPanel p3 = new JPanel();	
 
		p1.setLayout(new GridBagLayout());
		p2.setLayout(new GridBagLayout());
		p3.setLayout(new GridBagLayout());
 
		GridBagConstraints c = new GridBagConstraints();
		c.insets = new Insets(6,6,3,3);
 
		jPoly1 = new JTextField(20);
		jPoly2 = new JTextField(20);
		jResult = new JTextArea(1,20);
		jAdd = new JButton("ADD +");
		jSub = new JButton("SUB -");
		jMult = new JButton("MULT *");
		jDiv = new JButton("DIV  /");
		jExit = new JButton("EXIT");
		jExit.setBackground(Color.orange);
		JLabel label1 = new JLabel("Polynomial 1:");
		JLabel label2 = new JLabel("Polynomial 2:");
		JLabel label3 = new JLabel("Result: ");
 
		c.gridx = 0;
		c.gridy = 3;
		p1.add(label1, c);
 
		c.gridx = 5;
		c.gridy = 3;
		p1.add(jPoly1, c);
 
		c.gridx = 10;
		c.gridy = 3;
		c.fill = GridBagConstraints.HORIZONTAL;
		p2.add(jAdd, c);
 
		c.gridx = 15;
		c.gridy = 3;
		c.weightx = 0;
		p2.add(jSub, c);
 
		c.gridx = 0;
		c.gridy = 6;
		p1.add(label2, c);
 
		c.gridx = 5;
		c.gridy = 6;
		p1.add(jPoly2, c);
 
		c.gridx = 10;
		c.gridy = 6;		
		p2.add(jMult, c);
 
		c.gridx = 15;
		c.gridy = 6;
		c.fill = GridBagConstraints.HORIZONTAL;
		p2.add(jDiv, c);
 
		c.gridx = 0;
		c.gridy = 9;
		p1.add(label3, c);
 
		c.gridx = 5;
		c.gridy = 9;
		p1.add(jResult, c);	
 
		c.weightx = 0.0;
		c.gridwidth = GridBagConstraints.REMAINDER;
		c.gridx = 10;
		c.gridy = 9;
		p2.add(jExit, c);
 
		p1.setBorder(BorderFactory.createTitledBorder("Calculator"));
 
		p3.add(p1);
		p3.add(p2);
		add(p3);
 
	    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	    setTitle("Polynomial");
		setSize(525,225);
		setVisible(true);
 
		class ExitButtonListener implements ActionListener
		{
			public void actionPerformed(ActionEvent e) 
			{
				System.exit(0);				
			}		
 
		}
 
		class AddButtonListener implements ActionListener
		{			
			public void actionPerformed(ActionEvent e) 
			{
				Polynomial poly1 = new Polynomial();
				Polynomial poly2 = new Polynomial();
				Polynomial result = new Polynomial();
 
				String input1 = jPoly1.getText();
				String input2 = jPoly2.getText();
 
				poly1 = poly1.prep(input1);
				poly2 = poly2.prep(input2);
 
				result = result.addPoly(poly1,poly2);
 
				jResult.setText("");
				jResult.append(result.toString());
			}
 
		}
 
		class SubButtonListener implements ActionListener
		{
			public void actionPerformed(ActionEvent e) 
			{
				Polynomial poly1 = new Polynomial();
				Polynomial poly2 = new Polynomial();
				Polynomial result = new Polynomial();
 
				String input1 = jPoly1.getText();
				String input2 = jPoly2.getText();
 
				poly1 = poly1.prep(input1);
				poly2 = poly2.prep(input2);
 
				result = result.subPoly(poly1,poly2);
 
				jResult.setText("");
				jResult.append(result.toString());				
			}
 
		}
 
		ExitButtonListener bl1 = new ExitButtonListener();
		jExit.addActionListener(bl1);
 
		AddButtonListener bl2 = new AddButtonListener();
		jAdd.addActionListener(bl2);
 
		SubButtonListener bl3 = new SubButtonListener();
		jSub.addActionListener(bl3);
	}
 
}
 
//Main
public class Project {
	public static void main(String[] args) {
 
		MainWindow mw = new MainWindow();
 
	}
 
}

Sean4u thank you very much. i actually figured out a way to avoid using a treemap all to gether, but i'll be sure to take a look at that for the future.

Thank you very much to the both of you. I think i would have still been in square one had it not been for your help.

Originally Posted by snowguy13

Ah, that's very cool!
EDIT: I tried out your program, and it looks great! Something maybe to add (if you want to keep going with this): a recent history of operations the user has done (the addends, minuend/subtrahend, etc. and the answer), so that if for some reason the user must do many calculations and use the answers for more calculations, the answers are saved. Just a suggestion.

hehe thank you.

You know, thats actually a really good idea! That way, the user can take the result and perform more calculations on it without having to copy and paste all the time. i like it! thanks for the suggestion

Originally Posted by snowguy13

You seem to know your stuff about polynomials, but just checking: do you know how polynomial division works? It is quite a bit more complicated than the multiplication.

You know, i'm gonna be quite honest; its been about a year since i've taken any math courses so i am a bit rusty. Its amazing how quickly you forget things once you dont use them, even if you've taken 3 years worth of calculus and upper level differential equations lol. I actually found myself struggling to remember how to add polynomials :/

but if i'm not mistaking, for division, can i not just divide the coefficients and subtract the exponents from one another?

Originally Posted by snowguy13

partial fraction decomposition.

oh dear god! get it away from me!

Originally Posted by snowguy13

Yes, but remember that polynomial division depends on the LEADING (highest exponent) term only. Furthermore, you can only do polynomial division if the degree of the polynomial on top is equal to or greater than the degree of the polynomial on the bottom.

x^3 + 2x - 3
x - 3

The above works because the top polynomial's degree (3 in x^3) is greater than the bottom polynomial's degree (1 in x). However the below will not work:

x - 9
x^2

because x^2 has a higher degree than x - 9.

For the entire process of the division, see this page, which illustrates the divisions really well.

hmmm, well this definitely made my life much more difficult. Here i was thinking i was on the verge of completing this project... lol