JAVA 字符相关常用方法

Love The Way You Lie 2024-03-29 15:08 39阅读 0赞

## 数值和字符间转化 ##

# 字符和数值等价
    boolean b0 = 'a' == 97;       //true
    boolean b1 = 'a' == 97.0;     //true
    boolean b2 = 'a' == 97.0d;    //true
    boolean b3 = 'a' == 97.0f;    //true
    
    # 字符 转 数值
    int     a0 = 'a';      //97
    double  a1 = 'a';      //97.0
    
    # 数值 转 字符
    char d0 = 98;           //b
    char d1 = (char) 98.0;  //b

## 判断字符为 ：数字，字母，数字或字母，小写字母，大写字母，空白字符 ##

boolean digit1 = Character.isDigit('2'); //true
    boolean digit4 = Character.isDigit('0'); //true
    boolean digit2 = Character.isDigit('a'); //false
    boolean digit3 = Character.isDigit('!'); //false
    
    boolean digit1 = Character.isLetter('2'); //false
    boolean digit2 = Character.isLetter('0'); //false
    boolean digit3 = Character.isLetter('a'); //true
    boolean digit4 = Character.isLetter('!'); //false
    
    boolean digit1 = Character.isLetterOrDigit('2'); //true
    boolean digit2 = Character.isLetterOrDigit('0'); //true
    boolean digit3 = Character.isLetterOrDigit('a'); //true
    boolean digit4 = Character.isLetterOrDigit('!'); //false
    
    boolean digit1 = Character.isLowerCase('2'); //false
    boolean digit2 = Character.isLowerCase('A'); //false
    boolean digit3 = Character.isLowerCase('a'); //true
    boolean digit4 = Character.isLowerCase('!'); //false
    
    boolean digit1 = Character.isUpperCase('2'); //false
    boolean digit2 = Character.isUpperCase('A'); //true
    boolean digit3 = Character.isUpperCase('a'); //false
    boolean digit4 = Character.isUpperCase('!'); //false
    
    boolean digit1 = Character.isWhitespace('2');  //false
    boolean digit2 = Character.isWhitespace('\n'); //true
    boolean digit3 = Character.isWhitespace(' ');  //true
    boolean digit4 = Character.isWhitespace('!');  //false

## 数字字符，ASCLL码，字面量 ##

char ch1 = '1';
    char ch2 = '2';
    
    # 字符的ASCLL码
    int ch11 = ch1; // 49
    int ch21 = ch2; // 50
    
    # 数字字符的字面量
    int numericValue1 = Character.getNumericValue(ch1); // 1
    int numericValue2 = Character.getNumericValue(ch2); // 2

## String 获取 char ##

String str = "1,2,3,4,5";
    
    char c = str.charAt(2); // 2
    
    char[] cs = str.toCharArray(); // 1,2,3,4,5

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