Java determines whether it is a number
java中判断是否是数字的方法：
方法一：用JAVA自带的函数isDigit()方法判断
isDigit() 方法用于判断指定字符是否为数字。如果字符为数字，则返回 true；否则返回 false。
public static boolean isNumeric(String str){
for (int i = str.length();--i>=0;){
if (!Character.isDigit(str.charAt(i))){
return false;
}
}
return true;
}方法二：使用正则表达式"^[-\\+]?[\\d]*$"判断
/*
* 判断是否为整数
* @param str 传入的字符串
* @return 是整数返回true,否则返回false
*/
public static boolean isInteger(String str) {
Pattern pattern = Pattern.compile("^[-\\+]?[\\d]*$");
return pattern.matcher(str).matches();
}方法三：使用正则表达式"[0-9]*"判断
public static boolean isNumeric(String str){
Pattern pattern = Pattern.compile("[0-9]*");
return pattern.matcher(str).matches();
}方法四：使用正则表达式"^[0-9]*$"判断
public final static boolean isNumeric(String s) {
if (s != null && !"".equals(s.trim()))
return s.matches("^[0-9]*$");
else
return false;
}方法五：用ascii码
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;
}更多java知识请关注java基础教程。
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