Determine whether a character is a number in Java
Nov 19, 2019 pm 02:24 PM
一、使用自帶函數(shù)isDigit()
語法：
public static boolean isDigit(char ch)
實例：
public static boolean isNumeric (String str) {
for (int i = str.length(); --i >=0) {
if (!Character.isDigit(str.charAt(i))) {
return false;
}
}
return true;}二、使用正則表達式
實例1：
public static boolean isNumeric(String str) {
Pattern pattern = Pattern.compile("^[-\\+]?[\\d]*$");
return pattern.matcher(str).matches();}實例2：
public static boolean isNumeric(String str) {
if (str != null && !"".equals(str.trim())) {
return s.matches("^[0-9]*$");
}
return false;}實例3：
public static boolean isNumeric (String str) {
Pattern pattern = Pattern.compile("[0-9]*");
return pattern.matcher(str).matcher();}三、使用ASCII碼
public static boolean isNumeric (String str) {
for (int i = str.length(); --i>=0;) {
int chr = str.charAt(i);
if (chr < 48 || chr > 57) {
return false;
}
}
return true;}推薦教程：java開發(fā)入門
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