How to check if a string is parsable to float

Question

How can i check if a string can be parsed to a float number? I tried the common-lang NumberUtils library but sometimes i get wrong returns.

I don't know if that matter but my float numbers use comma seperators.

public TableCell call(TableColumn param) {

    return new TableCell<Course, String>() {
        @Override
        public void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);
            if (NumberUtils.isParsable(item)) {
                if (NumberUtils.toFloat(item) >= 5) {
                    this.setTextFill(Color.GREEN);
                } else if (NumberUtils.toFloat(item) < 5) {
                    this.setTextFill(Color.RED);
                }
                setText(item);
            }
        };
    }
}

Just parse them with `Float#parseFloat` and catch the exception. Don't overthink easy tasks like this one. — Tom, Aug 27 '16 at 15:37
You can use an Exception... See [this](http://stackoverflow.com/questions/3133770/how-to-find-out-if-the-value-contained-in-a-string-is-double-or-not) or [this](http://stackoverflow.com/questions/3543729/how-to-check-that-a-string-is-parseable-to-a-double). — Luis Teijon, Aug 27 '16 at 15:46

score 1 · Accepted Answer · edited May 23 '17 at 12:08

1

As mentioned before, use Float#parseFloat(String) but don't forget to replace the commas:

try {
    float val = Float.parseFloat(string.replace(',', '.'));
} catch (NumberFormatException e) {
    // Executed iff the string couldn't be parsed.
}

Inspired by this great answer, you can also check out the corresponding Float#valueOf(String) if you prefer a nasty regex.

edited May 23 '17 at 12:08

Community

1
1

answered Aug 27 '16 at 15:47

beatngu13

7,201
6
37
66

score 0 · Answer 2 · answered Aug 27 '16 at 15:43

A string can be parse to float if and only if.

All the chars in the strring are a valid chars in a float number(including decimal representations which is locale dependent)

the best way could be try to parse it forcing the code to throw an exception if something fails...

Float#parseFloat() will do the job in this case..

How to check if a string is parsable to float

2 Answers2