// 正则表达式 time:776ms

public boolean isNumber(String s) {

Pattern pattern = Pattern.compile("[-+]?(\\d+\\.?|\\.\\d+)\\d*(e[-+]?\\d+)?");

Matcher mat = pattern.matcher(s.trim());

return mat.matches();

}

// time:484ms

public boolean isNumber(String s) {

s = s.trim();

if (s.startsWith("-") || s.startsWith("+")) {

s = s. substring(1);

}

if ("".equals(s)) {

return false;

}

int dotPos = -1, ePos = -1;

for (int i = 0; i < s.length(); i++) {

if (dotPos == -1 && s.charAt(i) == '.') {

dotPos = i;

} else if (ePos == -1 && s.charAt(i) == 'e') {

ePos = i;

if (i+1 < s.length() && (s.charAt(i+1) == '-' || s.charAt(i+1) == '+')) {

i++;

}

} else {

if (Character.isDigit(s.charAt(i))) {

continue;

} else {

return false;

}

}

}

//xxx.xxexx

String startStr, midStr, endStr;

if (dotPos != -1 && ePos == -1) {

startStr = s.substring(0, dotPos);

endStr = s.substring(dotPos+1);

if (startStr.length() < 1 && endStr.length() < 1) {

return false;

}

} else if (dotPos == -1 && ePos != -1) {

startStr = s.substring(0, ePos);

if (startStr.length() < 1) {

return false;

}

endStr = s.substring(ePos+1);

if (endStr.startsWith("-") || endStr.startsWith("+")) {

endStr = endStr.substring(1);

}

if (endStr.length() < 1) {

return false;

}

} else if (dotPos != -1 && ePos != -1) {

if (dotPos >= ePos) {

return false;

}

startStr = s.substring(0, dotPos);

midStr = s.substring(dotPos+1, ePos);

if (startStr.length() < 1 && midStr.length() < 1) {

return false;

}

endStr = s.substring(ePos+1);

if (endStr.startsWith("-") || endStr.startsWith("+")) {

endStr = endStr.substring(1);

}

if (endStr.length() < 1) {

return false;

}

}

return true;

}

}