分解数学方程式字符串

Question

    Pattern pattern = Pattern.compile("([^\\d.]|[\\d.]++)");
    String[] equation =  pattern.split("5+3--323");
    System.out.println(equation.length);

I'm trying to break apart numbers (could be groups) and nonnumbers, in this example i was hoping for a size 6 array: 5, +, 3, -, -, 323

how can I do this?

Answer 1

Try using matcher, as in example below. It returns exactly what you are after.

import java.util.Arrays;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MathSplitTest
{
    public static void main(String[] args)
    {
        Pattern pattern = Pattern.compile("[0-9]+|[-+]");
        String string = "5+3--323";                 
        Matcher matcher = pattern.matcher(string);
        while(matcher.find())
            System.out.println("g0="+matcher.group(0));
    }
}

Answer 2

What about using a

new java.util.Scanner(new java.io.StringReader("5+3--323"));

instead?

http://download.oracle.com/javase/6/docs/api/java/util/Scanner.html

Answer 3

If your numbers are comma separated then first tokenize the String;

tok = new StringTokenizer(string, ",");

then try to create a number from each token. If it is not a number then it's a symbol:

while (tok.hasMoreTokens()){
    String tok = tok.nextTok();
    try {
          new Integer(tok);
    }catch (NumberFormatException e){

    }
}

If tok is not a number then a NumberFormatException is thrown.