String Formatter in GWT

Question

How do I format my string in GWT?

I made a method

  Formatter format = new Formatter();
    int matches = 0;
    Formatter formattedString = format.forma         


        

Answer 1

See the official page on GWT date and number formatting.

They suggest the following:

myNum decimal = 33.23232;
myString = NumberFormat.getFormat("#.00").format(decimal);

It is best to use their supported, optimized methods, than to cook up your own non-optimal method. Their compiler will be optimizing them all to nearly the same thing anyway in the end.

Answer 2

Another suggestion which makes use of JSNI and a nice JavaScript format function from another post:

import com.google.gwt.core.client.JsArrayString;

public abstract class StringFormatter {
    public static String format(final String format, final Object... args) {
        if (null == args || 0 == args.length)
            return format;
        JsArrayString array = newArray();
        for (Object arg : args) {
            array.push(String.valueOf(arg)); // TODO: smarter conversion?
        }
        return nativeFormat(format, array);
    }

    private static native JsArrayString newArray()/*-{
        return [];
    }-*/;

    private static native String nativeFormat(final String format, final JsArrayString args)/*-{
        return format.replace(/{(\d+)}/g, function(match, number) {
            return typeof args[number] != 'undefined' ? args[number] : match;
        });
    }-*/;
}

One can then make a call like this:

StringFormatter.format("Greetings {0}, it's {1} o'clock, which is a {2} statement", "Master", 8, false);

...with the result being

Greetings Master, it's 8 o'clock, which is a false statement

There is a potential to improve further at the TODO comment, e.g. utilise NumberFormat. Suggestions are welcome.

Answer 3

As an alternative you can use class NumberFormat:

NumberFormat fmt = NumberFormat.getDecimalFormat();
double value = 12345.6789;
String formatted = fmt.format(value);
// Prints 1,2345.6789 in the default locale

Answer 4

another very very simple replacement for java.text.MessageFormat.format() :

public static String format(final String format, final Object... args) {
    StringBuilder sb = new StringBuilder();
    int cur = 0;
    int len = format.length();
    while (cur < len) {
        int fi = format.indexOf('{', cur);
        if (fi != -1) {
            sb.append(format.substring(cur, fi));
            int si = format.indexOf('}', fi);
            if (si != -1) {
                String nStr = format.substring(fi + 1, si);
                int i = Integer.parseInt(nStr);
                sb.append(args[i]);
                cur = si + 1;
            } else {
                sb.append(format.substring(fi));
                break;
            }
        } else {
            sb.append(format.substring(cur, len));
            break;
        }
    }
    return sb.toString();
}

Answer 5

UPDATE: Please see (and vote up) Joseph Lust's post below before looking further at this answer.

Looks like formatter isn't included according to this post. However, they suggest some alternatives.

Answer 6

Maybe the easiest way to do something like String.format, can be do it with a String.replace, for instance;

instead of do String.format("Hello %s", "Daniel"); ==> "Hello %s".replace("%s", "Daniel"),

both give us the same result, but just the second way works in GWT client side