Android Decimal Number Input Filter

DecimalInputFilter.java

public class DecimalInputFilter extends android.text.method.DigitsKeyListener {
    private final WeakReference<EditText> mView;
    private int mDecimals = 18;

    public DecimalInputFilter(EditText txtView) {
        this(txtView, 18);
    }

    public DecimalInputFilter(EditText txtView, int decimals) {
        super(false, true);
        mView = new WeakReference<>(txtView);
        mDecimals = decimals;
    }

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        String tmp = mView.get().getText().toString();

        if (source.equals(",")) {
            return "";
        }

        if (source.equals(".") && tmp.isEmpty()) {
            return "0.";
        }

        if (tmp.equals("0") && !source.equals(".")) {
            return "";
        }

        if (source.equals(".") && tmp.contains(".")) {
            return "";
        }

        final int ptIndex = tmp.indexOf(".");
        if (ptIndex == -1) {
            if (tmp.equals("0") && source.equals(".")) {
                return source;
            }

            if (tmp.length() > 0 && ((tmp.charAt(0) == '0' && dstart > 0) || (tmp.charAt(0) != '0' && source.equals("0") && dstart == 0))) {
                return "";
            }
            return source;
        }


        if (ptIndex >= dstart) {
            if (tmp.charAt(0) == '.') {
                return source;
            }
            if ((tmp.charAt(0) == '0' && dstart > 0) || (tmp.charAt(0) != '0' && source.equals("0") && dstart == 0)) {
                return "";
            }
        } else if (ptIndex < dstart) {
            String decimals = tmp.substring(ptIndex + 1);
            if (decimals.length() >= mDecimals) {
                return "";
            }
        }

        return super.filter(source, start, end, dest, dstart, dend);
    }
}