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Java determines whether a character is a number

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2019-12-04 13:54:222660browse

Java determines whether a character is a number

java中判断字符是否数字的方法:(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;
}

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();  
}

方法三:

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

方法四:

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;
}

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