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Java determines whether a string is a number

Release: 2019-11-30 09:53:28
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Java determines whether a string is a number

java判断字符串是否数字的方法:(推荐:java视频教程

方法一: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;
}
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方法二:推荐,速度最快

/*
  * 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();  
  }
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方法三:

public static boolean isNumeric(String str){
    Pattern pattern = Pattern.compile("[0-9]*");
    return pattern.matcher(str).matches();   
}
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方法四:

public final static boolean isNumeric(String s) {
    if (s != null && !"".equals(s.trim()))
        return s.matches("^[0-9]*$");
    else
        return false;
}
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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;
}
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方法六:使用异常方式

public static boolean isNumeric(String str){
    try {
    Integer valueOf = Integer.valueOf(str);
        return true;
}catch(Exception e) {
return false;
}
}
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