Validate Variable Names According to Naming Conventions in Java
Let’s write a Java Program that checks whether a given variable name complies with the naming convention or not using Regular Expressions in Java.
Example for Validating Name of Variable Using Regex
Input: _myName
Output: CorrectInput: 2ndVariable
Output: Incorrect
Regex to Check Variable Name is Valid according to Naming Convention
Below is the implementation to Check Variable Name is Valid according to the Naming Convention:
Java
// Java Program Regex to Check Variable Name // Valid according to Naming Convention import java.util.regex.Matcher; import java.util.regex.Pattern; // Driver Class public class VariableNameValidator { // Main Function public static void main(String[] args) { // Example variable names String validVariable = "myVariable123" ; String invalidVariable = "3rdVariable" ; // Check if the variable names are valid boolean isValid1 = isValidVariableName(validVariable); boolean isValid2 = isValidVariableName(invalidVariable); // Display the results System.out.println(validVariable + " is valid: " + isValid1); System.out.println(invalidVariable + " is valid: " + isValid2); } private static boolean isValidVariableName(String variableName) { // Define the regular expression for a valid variable name String regex = "^[a-zA-Z_$][a-zA-Z_$0-9]*$" ; // Create a Pattern object Pattern pattern = Pattern.compile(regex); // Create a Matcher object Matcher matcher = pattern.matcher(variableName); // Check if the variable name matches the pattern return matcher.matches(); } } |
Output
myVariable123 is valid: true 3rdVariable is valid: false
Explanation of the above Program:
The regular phrase ^[a-zA-Z_$] is the main idea.[a-zA-Z_$0–9]*$ guarantees that the variable name is
- begins with a letter, dollar symbol ($), or underscore (_).
- followed by one or more letter, dollar sign, underscore, or digit occurrences.
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