public static int string2Int(String s, int defaultValue) {
    int i=defaultValue;
    try {
        i=Integer.parseInt(s);
    }
    catch(Exception ex) {
    }
    return i;
}

private static long getNumber(String str, long defaultValue) {
    if (str == null)
        return defaultValue;

    str = str.trim();
    if (str.length() == 0)
        return defaultValue;

    boolean isNegative;
    if (str.charAt(0) == '-' || str.charAt(0) == '+') {
        if (str.length() == 1)
            return defaultValue;
        else
            isNegative = str.charAt(0) == '-';
    } else if (Character.isDigit(str.charAt(0)))
        isNegative = false;
    else
        return defaultValue;

    final int radix = 10;
    final int zero_number_code = 49;
    final int nine_number_code = 57;
    long result = 0;
    boolean isFloat = false;

    for (int i = Character.isDigit(str.charAt(0)) ? 0 : 1; i < str.length(); i++) {
        char currentSymbol = str.charAt(i);
        if (currentSymbol == '.')
            if (isFloat)
                return defaultValue;
            else
                isFloat = true;

        if (currentSymbol != '.' &&
                (currentSymbol > nine_number_code || currentSymbol < zero_number_code))
            return defaultValue;

        if (!isFloat) {
            result *= radix;
            result += (currentSymbol + 1 - zero_number_code);
        }
    }

    return isNegative ? -result : result;
}

System.out.println(getNumber("142", 10));
System.out.println(getNumber("-72", 10));
System.out.println(getNumber("+19", 10));
System.out.println(getNumber("-19.11", 10));
System.out.println(getNumber("+19.16", 10));
System.out.println(getNumber("+19+.16", 10));
System.out.println(getNumber("+1.9+16", 10));
System.out.println(getNumber("1.1.16", 10));