CODEWITHSUNDEEP
javastring-conversion
SPlatten
SPlatten

Reputation: 5760

Java "100%" to number

Is there a built in routine in Java that will convert a percentage to a number for example, if the string contains 100% or 100px or 100, I want a float containing 100.

Using Float.parseInt or Float.valueOf result in an exception. I can write a routine that will parse the string and return the number, but I'm asking does this already exist?

Upvotes: 5

Views: 4835

Answers (4)

Sam Berry
Sam Berry

Reputation: 7844

Your comment on this answer indicates that you need to support the string ending in "%", "px", or nothing at all. If the only content of the string is the number and the unit, than you should be able to get away with:

float floatValue = new DecimalFormat("0.0").parse(stringInput).floatValue();

If your number is surrounded by other jibberish inside of the string, and you only desire the first number that occurs, than you can utilize ParsePosition:

String stringInput = "Some jibberish 100px more jibberish.";

int i = 0;
while (!Character.isDigit(stringInput.charAt(i))) i++;

float floatValue = new DecimalFormat("0.0").parse(stringInput, new ParsePosition(i)).floatValue();

Both of these solutions will give you the float value without requiring you to multiply the result by 100.

Upvotes: 1

SPlatten
SPlatten

Reputation: 5760

Thank you for the posts and suggestions, I did try using the solution posted by eg04lt3r, however the result was translated. In the end I wrote a simple function that does exactly what I require. I'm sure a good regular expression would have also worked.

    public static double string2double(String strValue) {
        double dblValue = 0;
        if ( strValue != null ) {
            String strResult = "";
            for( int c=0; c<strValue.length(); c++ ) {
                char chr = strValue.charAt(c);

                if ( !(chr >= '0' && chr <= '9'
                   || (c == 0 && (chr == '-' || chr == '+'))
                   || (c > 0 && chr == '.')) ) {
                    break;
                }
                strResult += chr;
            }
            dblValue = Double.parseDouble(strResult);
        }
        return dblValue;
    }

Upvotes: 0

eg04lt3r
eg04lt3r

Reputation: 2610

I think you can use:

NumberFormat defaultFormat = NumberFormat.getPercentInstance()
Number value = defaultFormat.parse("100%");

Upvotes: 20

LordAnomander
LordAnomander

Reputation: 1123

Use a StringBuffer to remove the % sign and then you can convert it.

if (percent.endsWith("%")) {
    String number = new StringBuffer(percent).deleteCharAt(percent.length() - 1);
    float f = Float.valueOf(number);
} else [Exception handling]

The approach above is nicer, but I figured I would fix my answer regarding the comment. You would have to make sure you are dealing with percent before removing a character.

Upvotes: 0

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