Android Utililty Methods String to Number Convert

final String number = "0123456789";
for (int i = 0; i < str.length(); i++) {
    if (number.indexOf(str.charAt(i)) == -1) {
        return false;
return true;

Pattern pattern = Pattern.compile("^[-\\+]?[\\d]*$");
return pattern.matcher(str).matches();

int index = str.indexOf(".");
if (index == -1) {
    return isIntegral(str);
if ((index == 0) || (index == str.length() - 1)) {
    return false;
String num1 = str.substring(0, index);
...

Pattern pattern = Pattern.compile("[0-9]*");
Matcher isNum = pattern.matcher(str);
if (!isNum.matches()) {
    return false;
return true;

if (string == null || string.length() == 0)
    return false;
int l = string.length();
for (int i = 0; i < l; i++) {
    if (!Character.isDigit(string.codePointAt(i)))
        return false;
return true;
...

int i = 0, len = s.length();
while (i < len
        && (Character.isLowerCase(s.charAt(i))
                || Character.isUpperCase(s.charAt(i)) || Character
                    .isDigit(s.charAt(i)))) {
    i++;
return (i >= len);
...

return Pattern.matches("[0-9[-\\s]]+", pString);

if (str == null || str.length() == 0) {
    return false;
Pattern pattern = Pattern.compile("[0-9]*");
return pattern.matcher(str).matches();

Pattern p = Pattern.compile("(\\D+)");
Matcher m = p.matcher(rawInput);
return m.find();

Boolean isNumber = false;
String expr = "^[0-9]+$";
if (str.matches(expr)) {
    isNumber = true;
return isNumber;