Import not working

[ribbs2521]

I was wondering if someone could tell me why I'm getting a compilation error when I try to run this. This code is straight out of a book so I must be missing something.

This is the error:
package edu.colorado.collections does not exist
import edu.colorado.collections.CharStack;

import edu.colorado.collections.CharStack;
import edu.colorado.collections.DoubleStack;
import edu.colorado.io.EasyReader;

public class BooleanCalc
{
	public static void main(String[] args)
	{
		EasyReader stdin = new EasyReader(System.in);
		double anser;

		System.out.println("Type a fully parenthesized arithmetic expression:");
		answer = readAndEvaluate(stdin);
		System.out.println("That evaluates to " + answer);
	}

	public static double readAndEvaluate(EasyReader input)
	{
		final char DECIMAL = '.';
		final char RIUGHT_PARENTHESIS = ')';
		final String SYMBOLS = "+-*/";

		DoubleStack number = new DoubleStack();
		CharStack operations = new CharStack();

		while (!input.isEOLN())
		{
			if (Character.isDigit(input.peek()) || (input.peek() == DECIMAL))
			{
				numbers.push(input.charInput());
			}
			else if (SYMBOLS.indexOf(input.peek()) >= 0)
			{
				operations.push(input.charInput());
			}
			else if (input.peek() == RIGHT_PARENTHESIS)
			{
				input.ignore();
				evaluateStackTops(numbers, operations);
			}
			else
			{
				input.ignore();
			}
		}
		input.skipLine();

		if (numbers.size() != 1)
			throw new IllegalArgumentException("Illegal input expression.");
		return numberls.pop();
	}

	public static void evaluateStackTops(DoubleStack numbers, CharStack operations)
	{
		double operand1, operand2;

		if ((numbers.size() < 2) || (operations.isEmpty()))
			throw new IllegalArgumentException("Illegal expression.");
		operand2 = numbers.pop();
		operand1 = numbers.pop();

		switch (operations.pop())
		{
			case '+': numbers.push(operand1 + operand2);
					  break;
			case '-': numbers.push(operand1 - operand2);
					  break;
			case '*': numbers.push(operand1 * operand2);
					  break;
			case '/': numbers.push(operand1 / operand2);
					  break;
			default:  throw new IllegalArgumentException("Illegal operation.");
		}
	}
}

[angelicsign]

yup,you are totally missing some packages.

edu.colorado.collections.CharStack;
edu.colorado.collections.DoubleStack;
edu.colorado.io.EasyReader;

this 3 packages are not inside J2SE API.
so you have to compile this 3 packages somewhere else
where the code will start like this normally

package edu.colorado

what packages are included in the java?
Java 2 Platform SE v1.4.2
you can refers to the link above.

[ribbs2521]

I'm not quite sure I understand what you mean by, compiling them somewhere else. How would I compile the packages? Can I do it in my code or do I do that manually.

I tried adding the package edu.colorado; to my code after the three imports but I get this error:

java:7: class, interface, or enum expected
package edu.colorado;

(there is a carat symbol under the P in the error message)

[angelicsign]

okay, i try to give you a simple example.

this code save inside the directory of vehicles
e.g. c:\directory\vehicles\car.java

[COLOR="Red"]package vehicles;[/COLOR]
public class car{
code here.......
}

save and compile the car.java to get a .class file

this is the main test program, may save at anywhere under same directory.
e.g. c:\directory\testProj\testing.java

[COLOR="Red"]import vehicles.car;[/COLOR]
public class testing{
code here....
}

you have to packaging it before you import the package.
similarly, you are trying to import a package that is not inside java library, so you have to find out where the edu.colorado package come from.
copy paste it then compile it to have a .class file so that you'll able to import
edu.colorado.*;

[ribbs2521]

OK, I think I've got it now, I'll let you know if I have any issues. Thanks for the clarification.

[angelicsign]

no problem, happy java-ing