Unlocking the Power of Java: Understanding Keywords and Identifiers
The Foundation of Java Programming: Keywords
In Java, keywords are the building blocks of the programming language. These predefined, reserved words hold special meanings that the compiler can understand. For instance, the keyword int indicates that a variable is of integer type, a 32-bit signed two’s complement integer. You can’t use keywords like int, for, or class as variable names, as they’re an integral part of the Java syntax.
The Complete List of Java Keywords
Get familiar with the comprehensive list of Java keywords, which also includes literals like true, false, and null. These literals can’t be used as identifiers, as they have predefined meanings in the language.
Java Identifiers: The Names Behind the Code
Identifiers are the names given to variables, classes, methods, and more. In the code snippet above, score is a variable, an identifier that can’t be replaced with a keyword. Keywords have predefined meanings, making them unusable as variable names.
The Rules of Naming an Identifier
To create valid identifiers, follow these essential rules:
- Avoid keywords: Don’t use keywords as identifiers, as they’re reserved for specific purposes.
- Case sensitivity: Identifiers are case-sensitive, so
scoreandScoreare treated differently. - Letter, $, or _: Identifiers can consist of letters, digits, and special characters like $ or _, but must start with a letter, $, or _.
- No whitespaces or symbols: Avoid using whitespaces, symbols like @, #, and other special characters in identifiers.
- Convention matters: While not mandatory, it’s conventional to start identifiers with a letter rather than $ or _.
Valid and Invalid Identifiers
Here are some examples to illustrate the point:
- Valid identifiers:
score,level,highestScore,number1,convertToString - Invalid identifiers:
class,float,1number,highest Score,@pple
By understanding Java keywords and identifiers, you’ll be well on your way to writing efficient, effective code.