Java.lang.Character.isJavaIdentifierStart() Method



The java.lang.Character.isJavaIdentifierStart(char ch) determines if the specified character is permissible as the first character in a Java identifier.

A character may start a Java identifier if and only if one of the following conditions is true −

  • isLetter(ch) returns true

  • getType(ch) returns LETTER_NUMBER

  • ch is a currency symbol (such as '$')

  • ch is a connecting punctuation character (such as '_').


Following is the declaration for java.lang.Character.isJavaIdentifierStart() method

public static boolean isJavaIdentifierStart(char ch)


ch − the character to be tested

Return Value

This method returns true if the character may start a Java identifier, false otherwise.




The following example shows the usage of lang.Character.isJavaIdentifierStart() method.

package com.tutorialspoint;

import java.lang.*;

public class CharacterDemo {

   public static void main(String[] args) {

      // create 2 char primitives ch1, ch2
      char ch1, ch2;

      // assign values to ch1, ch2
      ch1 = '3';
      ch2 = '_';

      // create 2 boolean primitives b1, b2
      boolean b1, b2;

       *  check if ch1, ch2 can start a java identifier
       *  and assign result to b1, b2
      b1 = Character.isJavaIdentifierStart(ch1);
      b2 = Character.isJavaIdentifierStart(ch2);

      String str1 = ch1 + " may start a Java identifier is " + b1;
      String str2 = ch2 + " may start a Java identifier is " + b2;

      // print b1, b2 values
      System.out.println( str1 );
      System.out.println( str2 );

Let us compile and run the above program, this will produce the following result −

3 may start a Java identifier is false
_ may start a Java identifier is true