How to parse through string and find doubles in Java

I have the following content in a file that I need to parse.

((-2, -1 ), ( 4, 2) ) ((-1.2, 0), (0, 0)) 
((0, 0), (10, -1)) 
((5, 3), (5, 4)) ((5, 1) , (5, 5)) 
((8, 3), (10, 3)) 
((8, 5), (11.5, 5)) 

So far, I have scanned through the file and taken the input line by line, saving them as strings, so one string would be ((-2, -1 ), ( 4, 2) ) ((-1.2, 0), (0, 0)). My question is where to go from here. How do I extract the doubles from this String. I have tried to use the parentheses as a delimiter, as well as changing all of the parentheses to commas, and then using a comma as a delimiter, but both of these ways give me errors. Any ideas?

Exception in thread "main" java.util.regex.PatternSyntaxException: Unclosed group near index 1 at java.util.regex.Pattern.error(Unknown Source) at
    java.util.regex.Pattern.accept(Unknown Source) at
    java.util.regex.Pattern.group0(Unknown Source) at
    java.util.regex.Pattern.sequence(Unknown Source) at
    java.util.regex.Pattern.expr(Unknown Source) at
    java.util.regex.Pattern.compile(Unknown Source) at
    java.util.regex.Pattern.<init>(Unknown Source) at
    java.util.regex.Pattern.compile(Unknown Source) at
    java.lang.String.replaceAll(Unknown Source)

The whole purpose of this is to create points from these doubles. For example, ((0, 0), (10, -1)) would create two points, (0,0) and (10, -1). I have created the point class and it takes in two doubles in the constructor. Here is what I tried:

      String toParse = "((0, 0), (10, -1))";
    toParse.replaceAll("(", ",");
    toParse.replaceAll(")", ",");
    Scanner stringScanner = new Scanner(toParse);
    stringScanner.useDelimiter(",");
    while(stringScanner.hasNextDouble()开发者_Go百科){

ect

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The error message you get is because ( and ) are special regex characters: so whenever you want to replace (or match) them, you need to escape them with a backslash:

toParse.replaceAll("\\(", ",");
...

That said, you might want to use a Pattern/Matcher approach here:

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

public class Test {
    public static void main(String[] args) {

        String source =
                "((-2, -1 ), ( 4, 2) ) ((-1.2, 0), (0, 0))  \n" +
                "((0, 0), (10, -1))                         \n" +
                "((5, 3), (5, 4)) ((5, 1) , (5, 5))         \n" +
                "((8, 3), (10, 3))                          \n" +
                "((8, 5), (11.5, 5))                        \n";

        Matcher m = Pattern.compile("-?\\d+(\\.\\d+)?").matcher(source);

        while(m.find()) {
            double value = Double.parseDouble(m.group());
            System.out.println("value=" + value);
        }
    }
}

which produces:

value=-2.0
value=-1.0
value=4.0
value=2.0
value=-1.2
value=0.0
value=0.0
value=0.0
value=0.0
value=0.0
value=10.0
value=-1.0
value=5.0
value=3.0
value=5.0
value=4.0
value=5.0
value=1.0
value=5.0
value=5.0
value=8.0
value=3.0
value=10.0
value=3.0
value=8.0
value=5.0
value=11.5
value=5.0

What the code does: it searches for the pattern -?\d+(\.\d+)? and parses each string that matches said pattern to a double. The pattern itself means:

-?         # an optional minus sign
\d+        # followed by one or more digits
(\.\d+)?   # followed by an optional decimal DOT with one or more digits

---

Here's a left-field suggestion for you. Search and replace the brackets from ( and ) to [ and ] then use simply use an off-the-shelf JSON parser.

---

The following RegEx will capture the pair of numbers, separated by a comma and enclosed withing parantheses. So, it given: ((4,2), it should capture: 4,2 And given: ( -1.0,0) it would capture -1.0,0. From that point on you can split the string by , trim the leading and trailing spaces and parse the remainder as a Double.

Pattern p = Pattern.compile("\(([^(]+,[^)]+)\)");
Matcher matcher = p.matcher("((-2, -1 ), ( 4, 2) ) ((-1.2, 0), (0, 0))");
while (matcher.find()) 
{
    String str = matcher.group(); // this should in turn take the following values
                                  // -2, -1 
                                  //  4, 2
                                  // -1.2, 0
                                  // 0, 0
    String[] numbers = str.split(",");
    if(numbers.length == 2)
    {
        // numbers[0] should be the first coordinate
        // and numbers[1] should be the second
        Double first = new Double(numbers[0].trim());
        Double second = new Double(numbers[1].trim());
    }
}