Section 1 - Keywords
A keyword is one of the words used to define the syntax of the Java programming language. The following are a few examples of Java keywords:
class public static void
Section 2 - Identifiers
An identifier is a valid name. Java defines the following rules for identifiers:
- The first character must be an uppercase or lowercase letter, $, or _
- Subsequent characters must be an uppercase or lowercase letter, $, _, or a digit
- Identifiers may not contain punctuation or whitespace
- Identifiers may not be the same as a keyword
- There is no limit to the length of a Java identifier
The following are examples of valid Java identifiers:
hello1 $mother _father BaBy hello_world
The following are examples of invalid Java identifiers:
1hello (identifier may not begin with a digit) hello world (identifier may not contain whitespace) hello;world (identifier may not contain punctuation)
Java is a case sensitive language: baby, BABY, and BaBy are three different identifiers.
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