Java Keyword and Identifier

Java Keywords

In a programmer’s life, knowing all the keywords are very essential to build a program properly. In this article, we will discuss all the keywords that JDK has in reserve.In the Java programming language,   there are several reserved words that have a predefined meaning in the language. Because of this, programmers cannot use keywords in some contexts, such as names for variables, methods, classes, or as any other java identifiers.

Keywords in Java are reserved words that have predefined meanings and cannot be used for any other purpose than their intended use in the language. Some examples of Java keywords include class, public, static, void, if, else, for, while, return, try, catch, finally, extends, implements, etc.

List of Java Reserved Keywords

Java Identifiers

Java identifiers are names given to various elements in a Java program, such as variables, methods, classes, packages, and interfaces.

All Java variables must be identified with unique names.

These unique names are called identifiers.

Rules for Java Identifiers:

1. Starting Characters: Identifiers must begin with a letter (a-z or A-Z), a dollar sign ($), or an underscore (_). They cannot start with a digit or any other special character.
2. Subsequent Characters: After the initial character, identifiers may contain letters, digits, underscores, or dollar signs. They cannot contain spaces or other special characters.
3. Case Sensitivity: Java identifiers are case-sensitive, meaning uppercase and lowercase letters are distinct. For example, “myVariable” and “MyVariable” are treated as different identifiers.
4. Reserved Keywords: Identifiers cannot be Java keywords or reserved words, as these have predefined meanings in the language. Attempting to use a reserved word as an identifier will result in a compilation error.
5. Length: Identifiers can be of any length, but it’s advisable to keep them concise and meaningful for improved code readability. Excessively long identifiers may hinder readability and comprehension.

Best Practoice for Java Naming Identifiers

Examples of Java Identifiers

Example 1 – Variables

int itemCount;
double totalPrice;
String customerName;

Example 2 – Class

public class ShoppingCart {
// Class members and methods
}

class OrderProcessing {
// Class members and methods
}

Example 3 – Method

public void calculateTotalPrice() {
// Method implementation
}

private String formatCustomerName(String firstName, String lastName) {
// Method implementation
}

Example 4 – Interface –

public interface PaymentGateway {
// Interface methods
}

Java Keywords vs Identifiers

Here are some key differences between keywords and identifiers:

Conclusion

Java keywords are the building blocks of Java programming, defining the syntax and structure of the code. Identifiers, on the other hand, allow programmers to name variables, methods, classes, and other elements in a meaningful way. Adhering to Java’s conventions for both keywords and identifiers is essential for writing clear, readable, and efficient code. A solid grasp of these concepts is foundational for successful Java development, enabling programmers to navigate and utilize the language effectively.

Frequently Asked Questions