Java determines whether a string is a number-JavaBase-php.cn

Java determines whether a string is a number

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Release： 2019-12-02 10:41:48

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Java determines whether a string is a number

java判断字符串是否为数字的方法：（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、org.apache.commons.lang

org.apache.commons.lang.StringUtils;

StringUtils.isNumeric(null)   = false
 StringUtils.isNumeric("")     = true
 StringUtils.isNumeric("  ")   = false
 StringUtils.isNumeric("123")  = true
 StringUtils.isNumeric("12 3") = false
 StringUtils.isNumeric("ab2c") = false
 StringUtils.isNumeric("12-3") = false
 StringUtils.isNumeric("12.3") = false

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