Question

Is there a better way to build strings with formatting and appending than this example? This is a Java question.

Edit: It seems that it would be better if Formatter() was capable of being more like StringBuilder() or that StringBuilder() be capable of being like Formatter(). I especially do not like having to catch an exception given that this is merely a “toString” kind of method, that is to say, trivial. Also, what if I want to append an integer via %d after the loop?

    String methodToYieldMyInstanceAsString()
    {
        Formatter f = new Formatter();
        f.format("%s %d\n", thing1, thing2);

        for (Entry<KeyType, ValueType> entry: map.entrySet())
        {
            try
            {
                f.out().append(entry.getKey().asString() + " ");
                f.out().append(entry.getValue().asString() + "\n");
            }
            catch (IOException e)
            {
                throw new RuntimeException();
            }
        }
        return f.toString();
    }

One good thing about this code is that I only use one Formatter object, for what it’s worth.

Answer 1

You can avoid the IOException if you call the format method yourself, it throws only unchecked exceptions. Just change your code slightly:

StringBuilder builder = new StringBuilder();
Formatter f = new Formatter(builder);

for (...) {
    f.format("%s %d\n", entry.getKey(), entry.getValue());
}

return builder.toString();