I need a source code for JAVA for balancing a chemical equation.

CH4 + O2 = CO2 + 2 H20
CH4 + 2 O2 = CO2 + 2 H20

I made a quick google search (i am going to begin my first Java class in a few days, a long with C#) and I found this:

package com.googlecode.cceb.chemistry;

import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

import com.googlecode.cceb.math.Fraction;
import com.googlecode.cceb.math.Matrix;

/**
 * A formula represents a chemical equation. It is a balance-able set of
 * terms(compounds).
 * 
 * Formula Syntax: e.g. Ag(SO4)2 = Ag + SO4 Constructs a new Formula
 * 
 * @author Vsunder, ajc
 */
public class Formula {

        private ArrayList<Compound> reactants, products;

        public Formula(String input) {
                reactants = new ArrayList<Compound>();
                products = new ArrayList<Compound>();
                StringTokenizer st = new StringTokenizer(input);

                boolean isReactant = true; // we start at reactant side
                // construct compounds directly from tokenized output(from spaces)
                // store compounds as reactants/products
                while (st.hasMoreTokens()) {
                        String cp = st.nextToken();
                        if (cp.equals("=")) { // an '=' indicates if we're on reactants or
                                // products
                                isReactant = false;
                        } else if (cp.equals("+")) {
                                // ignore if a '+'
                        } else {
                                // add the compound to the proper list depending if it is
                                // reactant or product
                                (isReactant ? reactants : products).add(new Compound(cp));
                        }
                }
        }

        public String balance() throws InvalidElementException,
                        InvalidFormulaException {
                double[][] values;
                Matrix solver = new Matrix();
                int numcp = reactants.size() + products.size();
                /*
                 * for every element found in every compound, make a list of unique
                 * elements to count and put in array (and put in array)
                 */
                ArrayList<Element> distel = new ArrayList<Element>();
                for (int i = 0; i < reactants.size(); i++) {
                        List<Element> temp = reactants.get(i).RAMIREZ_getConstituents();
                        for (int j = 0; j < temp.size(); j++) {
                                if (!distel.contains(temp.get(j))) {
                                        distel.add(temp.get(j));
                                }
                        }
                }
                for (int i = 0; i < products.size(); i++) {
                        List<Element> temp = products.get(i).RAMIREZ_getConstituents();
                        for (int j = 0; j < temp.size(); j++) {
                                if (!distel.contains(temp.get(j))) {
                                        distel.add(temp.get(j));
                                }
                        }
                        // figure out which elements we will solve for and if there are
                        // enough
                }

                values = new double[numcp - 1][numcp];

                ArrayList<Compound> allcomp = new ArrayList();
                allcomp.addAll(reactants);
                allcomp.addAll(products);
                /*
                 * convert to matrix: count compound (if there are 4 compounds: 3
                 * equations in order to know how many equations to make (n-1))
                 */
                for (int i = 0; i < numcp - 1; i++) {
                        for (int j = 0; j < numcp; j++) {
                                if (i + 1 > distel.size()) {
                                        break;
                                }
                                values[i][j] = allcomp.get(j).getElementCount(distel.get(i));

                        }
                }
                solver.setValues(values);
                // rref
                solver.rref();
                values = solver.getValues();
                // extracting relevant values
                double[] balanced = new double[numcp];
                for (int i = 0; i < numcp - 1; i++) {
                        balanced[i] = values[i][numcp - 1];
                }
                /*
                 * Move negative(products) to the products side)
                 */

                for (int i = allcomp.size() - 2; i > reactants.size() - 1; i--) {
                        balanced[i] *= -1;
                }
                balanced[numcp - 1] = 1;

                /*
                 * convert to fractions
                 */
                Fraction[] b = new Fraction[numcp];
                for (int i = 0; i < numcp; i++) {
                        b[i] = new Fraction(balanced[i]);
                }
                int[] b1 = new int[numcp];
                int m = b[0].cmult(b);
                for (int i = 0; i < numcp; i++) {
                        b[i].mult(m);
                        b1[i] = b[i].getNumerator();
                }

                /*
                 * lcm/gcd stuff
                 */
                b1 = lcm(b1);
                /*
                 * Creates String
                 */
                String[] a = new String[numcp];
                String answer = new String();

                for (int i = 0; i < reactants.size(); i++) {
                        if ((double) b1[i] == 1) {
                                a[i] = reactants.get(i).toString();
                        } else {
                                a[i] = b1[i] + reactants.get(i).toString();
                        }
                }
                for (int i = 0; i < products.size(); i++) {
                        if (b1[i + reactants.size()] == 1) {
                                a[i + reactants.size()] = products.get(i).toString();
                        } else {
                                a[i + reactants.size()] = b1[i + reactants.size()]
                                                + products.get(i).toString();
                        }
                }
                for (int i = 0; i < numcp; i++) {
                        if (i != reactants.size() - 1 && i != reactants.size()) {
                                if (i == 0) {
                                        answer = answer.concat(a[i]);
                                } else {
                                        answer = answer.concat(" + ");
                                        answer = answer.concat(a[i]);
                                }
                        } else {
                                if (i == reactants.size() - 1) {
                                        answer = answer.concat(" + ");
                                        answer = answer.concat(a[i]);
                                        answer = answer.concat(" = ");
                                } else {
                                        answer = answer.concat(a[i]);
                                }
                        }
                }

                return answer;

                /*
                 * LCM: biggest whole numbers Help ionno how to do this.
                 */

        }

        public String toString() {
                return reactants.toString() + products.toString();
        }

        private int[] lcm(int[] a) {
                int g = gcd(a);
                if (g == 1) {
                        return a;
                } else {
                        for (int i = 0; i < a.length; i++) {
                                a[i] /= g;
                        }
                        return lcm(a);
                }
        }

        private final int gcd(int[] x) {
                if (x.length < 2) {
                        throw new Error("Do not use this method if there are less than"
                                        + " two numbers.");
                }
                int tmp = gcd(x[x.length - 1], x[x.length - 2]);
                for (int i = x.length - 3; i >= 0; i--) {
                        if (x[i] < 0) {
                                throw new IllegalArgumentException("Cannot compute the least "
                                                + "common multiple of " + "several numbers where "
                                                + "one, at least," + "is negative.");
                        }
                        tmp = gcd(tmp, x[i]);
                }
                return tmp;
        }

        /**
         * Method that calculates the Greatest Common Divisor (GCD) of two positive
         * integer numbers.
         * */
        private final int gcd(int x1, int x2) {
                if (x1 < 0 || x2 < 0) {
                        throw new IllegalArgumentException("Cannot compute the GCD "
                                        + "if one integer is negative.");
                }
                int a, b, g, z;

                if (x1 > x2) {
                        a = x1;
                        b = x2;
                } else {
                        a = x2;
                        b = x1;
                }

                if (b == 0)
                        return 0;

                g = b;
                while (g != 0) {
                        z = a % g;
                        a = g;
                        g = z;
                }
                return a;
        }

}

I am not sure if it will help, but i found it here

By the way, it is best if you show us what you have written so we can guide you on fixing your problems rather than us doing 100% of your work (espicially your school assignment), do you know what I mean?

thanks for trying but this didnt work ):
says something about the formulas used was unsafe or something/

hmmm, i am still new to java... so i have to figure it out somehow (unless my professor on the first day of class will revise it for me). At the moment I will have announce defeat but I am sure someone else maybe able to assist you from here.

says something about the formulas used was unsafe or something/

What do you mean by that?

Need to be creepy or anything, but i have also noticed you have asked this question on other sites, and I noticed that on Yahoo! someone said for you to do it yourself, try using this source i provided so they can fix it a long with our fellow Daniwebbers

i cant post it on yahoo because it exceeds the character amount.
asdofhasdfasjdf, i can do this but its going to take me a while and i have to study for other things. SORRY):

asdofhasdfasjdf, i can do this but its going to take me a while and i have to study for other things. SORRY):

There is no point from avoiding this question because of other "studies", your going to have to learn this one way or another, you'd only cheat yourself if you didn't get your question answered.

That is not the best way to handle things in life.

May or may not be. If the OP is not ready or knew himself/herself that this is not the path to go through, the OP should look for another way. The project requires the OP to have knowledge of how to balance a chemistry equation and how to translate the concept to programming. This is actually still far from what Computer Scientist is because it is just basic. If the OP could not take it now but still have an opportunity to choose other paths, the OP should do it. Trying to go through this path with the current situation may result in a worse situation.

Edited 3 Years Ago by Taywin

Comments
Amen :)
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