Basic Concepts and Terms

Computers use binary numbers internally. A character is stored in a computer as a sequence of 0s and 1s. Mapping a character to its binary representation is called encoding. There are different ways to encode a character. How characters are encoded is defined by an encoding scheme.（和数字一样，普通字符也是以二进制的形式存储在计算机中，将字符映射为其对应的二进制表达的过程就叫编码，编码有多种不同的方案或标准，最常见的有ASCII和Unicode，Unicode支持全球所有字符，Unicode常见的实现有UTF-8、UTF-16等，常见的中文编码有GBK和GB2312）

Character Type Declaring and Operation

char letter1 = 'a';//字符需要用单引号，'a'为字符，"a"为字符串

char letter2 = '4'; 

char letter3 = '\u0061'; //除了直接用字符，字符字面量还能用Unicode编码表示，'a'和'\u0061'是等价的

char letter4 = '欢'; //字面量有中文字符时，源文件的编码方式需要设置为中文编码GBK，或编译时指明编码方式，例如以utf-8编码的源文件编译时采用：javac -encoding utf-8 XXX.java