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java中判断字符串是否为数字的三种方法

2011-06-16 21:06:50| 分类：默认分类 | 标签： |举报 |字号大中小订阅

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1、用JAVA自带的函数
public static boolean isNumeric(String str){
for (int i = str.length();--i>=0;){
   if (!Character.isDigit(str.charAt(i))){
    return false;
   }
}
return true;
}

2、用正则表达式
public static boolean isNumeric(String str){
Pattern pattern = Pattern.compile("[0-9]*");
return pattern.matcher(str).matches();
}

3、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;
}

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