术语关键字"和标识符"不是特定于 Java 的.

The terms "keyword" and "identifier" are not Java specific.

关键字是来自 Java 关键字列表 向编译器提供指令.由于关键字是保留的，程序员不能将它们用于变量或方法名称.

A keyword is a reserved word from the Java keyword list provide the compiler with instructions. As keywords are reserved, they cannot be used by the programmer for variable or method names.

示例:

final
class
this
synchronized

标识符是变量、方法、类、包和接口的名称.它们必须由字母、数字、下划线 _ 和美元符号 $ 组成.标识符只能以字母、下划线或美元符号开头.

Identifiers are the names of variables, methods, classes, packages and interfaces. They must be composed of letters, numbers, the underscore _ and the dollar sign $. Identifiers may only begin with a letter, the underscore or a dollar sign.

示例:

int index;
String name;

index 和 name 是此处的有效标识符.int 是关键字.

index and name are valid identifiers here. int is a keyword.

关键字不能用作标识符.

A keyword cannot be used as an identifier.