Simple currency TextWatcher, providing a quick and dirty way to generate formatted price strings.

TextWatcher.java

public class LocalCurrencyTextWatcher implements TextWatcher {
    private String separator
    String beforeText = "";
    String finalText = "";
    boolean changing = false;

    public LocalCurrencyTextWatcher(String separator) {
        this.separator = separator;
    }
  
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        if (s.toString().length() > 0) {
            beforeText = s.toString();
        }
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        if (changing) return;

        String sequence = s.toString();

        if (sequence.length() > 0 && count > 0) {
            if (beforeText.contains(separator)) {
                String newPart = s.subSequence(start, start + count).toString();
                char sepChar = separator.charAt(0);
                if (newPart.contains(separator)) {
                    // prevent second decimal separator
                    StringBuffer buffer = new StringBuffer(sequence);
                    int removeIndex = sequence.lastIndexOf(sepChar);
                    finalText = buffer.replace(removeIndex, removeIndex + 1, "").toString();
                } else if (sequence.substring(sequence.indexOf(sepChar) + 1).length() > 2) {
                    // limit cents part
                    int toRemove = 1;
                    finalText = sequence.substring(0, sequence.length() - toRemove);
                }
                else {
                    finalText = sequence;
                }
            } else {
                finalText = sequence;
            }
        } else {
            finalText = sequence;
        }
    }

    @Override
    public void afterTextChanged(Editable s) {
        if (changing) {
            // prevent infinite loop
            changing = false;
            beforeText = "";
            finalText = "";
        } else if (beforeText.length() > 0 &&
                !finalText.equals(s.toString())) {
            changing = true;
            s.replace(0, s.length(), finalText);
        }
    }
}