extracting a double value from a string of alphanumeric characters in Java

Question

I'm looking for a function that does what the heading says.

I ended up with writing code that parses through every character and making another string then Double.parseDouble. Which threw StringIndexoutOfBounds exception. Which is clearly not the way to go.

The block of code is here

int i = 0;
char c = q.charAt(i);
if (Character.isDigit(c)) {
    try {
        String h = "" + c;
        while (Character.isDigit(c) || c == '.') {
            if (i == (q.length() - 1)) if (Character.isDigit(q.charAt(i + 1)) || (q.charAt(i + 1) == '.')) {
                Log.i("CalcApps", "within while");
                h += q.charAt(i + 1);
            }
            i++;
            c = q.charAt(i);
        }
        result = Double.parseDouble(h);
    } catch (Exception e) {
        Log.i("MyApps", "Index is out of bounds");
    }
}

What format does your `String` have? Maybe you just need to `trim()` or clean it up before the call to `Double.parseDouble()`. — Keppil, Jul 24 '12 at 09:45

score 3 · Answer 1 · answered Jul 24 '12 at 09:51

3

You would try something like this:

public static void main(String[] args) {
        String str = "dsde1121zszs.15szs"; 
        Double d = Double.valueOf(str.replaceAll("[^0-9\\.]", ""));
        System.out.println(d);
    }

answered Jul 24 '12 at 09:51

M. Abbas

6,409
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score 0 · Accepted Answer · edited May 23 '17 at 11:55

0

You should use DecimalFormat and avoid creating your own implementation of a parser. See this question for some examples.

edited May 23 '17 at 11:55

Community

1
1

answered Jul 24 '12 at 09:49

kgiannakakis

103,016
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I'm not trying to format a decimal. I'm trying to pasrse a double value : ex: q = 123.1445+e^x(23.2) Ans: 123.1445, 23.2 – prasana venkat Jul 24 '12 at 11:03
You can do that with the `Number DecimalFormat.parse(String string, ParsePosition position)` method – kgiannakakis Jul 24 '12 at 11:11

extracting a double value from a string of alphanumeric characters in Java

2 Answers2