CODEWITHSUNDEEP
java
Edward
Edward

Reputation: 91

Getting a double out of a string

i have a string containing the following: "Did It Your Way, 11.95 The History of Scotland, 14.50, Learn Calculus in One Day, 29.95" is there any way to get the doubles from this string?

Upvotes: 9

Views: 25513

Answers (8)

Stepan
Stepan

Reputation: 1431

Use scanner (example from TutorialPoint). Regex expressions suggested above fail on this example: "Hi! -4 + 3.0 = -1.0 true" detects {3.0, 1,0}.

   String s = ""Hello World! -4 + 3.0 = -1.0 true"";

   // create a new scanner with the specified String Object
   Scanner scanner = new Scanner(s);

   // use US locale to be able to identify doubles in the string
   scanner.useLocale(Locale.US);

   // find the next double token and print it
   // loop for the whole scanner
   while (scanner.hasNext()) {

   // if the next is a double, print found and the double
   if (scanner.hasNextDouble()) {
   System.out.println("Found :" + scanner.nextDouble());
   }

   // if a double is not found, print "Not Found" and the token
   System.out.println("Not Found :" + scanner.next());
   }

   // close the scanner
   scanner.close();
   }

Upvotes: 1

Endorox
Endorox

Reputation: 99

Here is how I did it when I was getting input from a user and didn't know what it would look like:

    Vector<Double> foundDoubles = new Vector<Double>();

    Scanner reader = new Scanner(System.in);
    System.out.println("Ask for input: ");

    for(int i = 0; i < accounts.size(); i++){
        foundDoubles.add(reader.nextDouble());
    }

Upvotes: 0

ron
ron

Reputation: 9364

Use Regular Expressions (regex[p]) module of your favourite language, construct a Matcher for the pattern \d+\.\d+, apply the matcher for the input string and you get the matching substrings as capture groups.

Upvotes: -2

Ian Bishop
Ian Bishop

Reputation: 5205

Java provides Scanner which allows you to scan a String (or any input stream) and parse primitive types and string tokens using regular expressions.

It would likely be preferrable to use this rather than writing your own regex, purely for maintenance reasons.

Scanner sc = new Scanner(yourString);
double price1 = sc.nextDouble(), 
       price2 = sc.nextDouble(), 
       price3 = sc.nextDouble();

Upvotes: 9

Bohemian
Bohemian

Reputation: 425023

This finds doubles, whole numbers (with and without a decimal point), and fractions (a leading decimal point):

public static void main(String[] args)
{
    String str = "This is whole 5, and that is double 11.95, now a fraction .25 and finally another whole 3. with a trailing dot!";
    Matcher m = Pattern.compile("(?!=\\d\\.\\d\\.)([\\d.]+)").matcher(str);
    while (m.find())
    {
        double d = Double.parseDouble(m.group(1));
        System.out.println(d);
    }
}

Output:

5.0
11.95
0.25
3.0

Upvotes: 3

Nicolae Albu
Nicolae Albu

Reputation: 1245

String text = "Did It Your Way, 11.95 The History of Scotland, 14.50, Learn Calculus in One Day, 29.95";

List<Double> foundDoubles = Lists.newLinkedList();

String regularExpressionForDouble = "((\\d)+(\\.(\\d)+)?)";
Matcher matcher = Pattern.compile(regularExpressionForDouble).matcher(text);
while (matcher.find()) {
    String doubleAsString = matcher.group();
    Double foundDouble = Double.valueOf(doubleAsString);
    foundDoubles.add(foundDouble);
}

System.out.println(foundDoubles);

Upvotes: 0

AlexR
AlexR

Reputation: 115328

Use regular expressions to extract doubles, then Double.parseDouble() to parse:

Pattern p = Pattern.compile("(\\d+(?:\\.\\d+))");
Matcher m = p.matcher(str);
while(m.find()) {
    double d = Double.parseDouble(m.group(1));
    System.out.println(d);
}

Upvotes: 14

user684934
user684934

Reputation:

If you're interested in any and all numbers with digits, a single period, and more digits, you want to use regular expressions. Such as \s\d*.\d\s, indicating a space, followed by digits, a period, more digits, and finished off with a space.

Upvotes: 1

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