Evaluator.java

package app;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;

public class Evaluator {

	/**
	 * @param args
	 */
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		while (true) {
			System.out.print("\nEnter the expression, or hit return to quit => ");
			String expr = sc.nextLine();
			if (expr.length() == 0) {
				break;
			}
			ArrayList<Variable> vars = new ArrayList<>(); 
			ArrayList<Array> arrays = new ArrayList<>();
			Expression.makeVariableLists(expr, vars, arrays);
			
			
			

			System.out.print("Enter variable values file name, or hit return if no variables => ");
			String fname = sc.nextLine();
			if (fname.length() != 0) {
				Scanner scfile = new Scanner(new File(fname));
				Expression.loadVariableValues(scfile, vars, arrays);
			}
			for(Variable elements:vars)
			{
				System.out.println(elements);
			}
			
			for(Array elements:arrays)
			{
				System.out.println(elements);
			}
			
			System.out.println("Value of expression = " + Expression.evaluate(expr,vars,arrays));
		}
		sc.close();
	}
}