Open In App

Character.isJavaIdentifierStart() Method in Java

Improve
Improve
Like Article
Like
Save
Share
Report

The Character.isJavaIdentifierStart(int codePoint) is an inbuilt method in java that determines if the character (Unicode code point) is permissible as the first character in a Java identifier. It is to be noted that 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 ‘_’).

Syntax:

public static boolean isJavaIdentifierStart(int codePoint)

Parameters: The parameter codePoint is of the integer type and refers to the character (Unicode code point) that is to be tested.

Return value: The isJavaIdentifierStart(int codePoint) method of Character class returns true if the character may start a Java identifier; false otherwise.

Below programs illustrate the Character.isJavaIdentifierStart() method:

Program 1:




// Java program to illustrate
// Character.isJavaIdentifierStart() method 
import java.lang.*;
  
public class gfg {
  
    public static void main(String[] args)
    {
  
        // Create 2 int primitives c1, c2
        int c1 = 0x0039, c2 = 0x004b, c3 = 0x0081;
  
        // Assign isJavaIdentifierPart results of 
        // c1, c2 to boolean primitives bool1, bool2
  
        boolean bool1 = Character.isJavaIdentifierStart(c1);
        boolean bool2 = Character.isJavaIdentifierStart(c2);
        boolean bool3 = Character.isJavaIdentifierStart(c3);
  
        String str1 = "c1 may start a Java identifier is " + bool1;
        String str2 = "c2 may start a Java identifier is " + bool2;
        String str3 = "c3 may start a Java identifier is " + bool3;
  
        // Print bool1, bool2 values
        System.out.println(str1);
        System.out.println(str2);
        System.out.println(str3);
    }
}


Output:

c1 may start a Java identifier is false
c2 may start a Java identifier is true
c3 may start a Java identifier is false

Program 2:




// Java program to illustrate
// Character.isJavaIdentifierStart() method 
import java.lang.*;
  
public class gfg {
  
    public static void main(String[] args)
    {
  
        // Create 2 int primitives c1, c2
        int c1 = 0x0034, c2 = 0x005a;
  
        // Assign isJavaIdentifierPart results of 
        // c1, c2 to boolean primitives bool1, bool2
  
        boolean bool1 = Character.isJavaIdentifierStart(c1);
        boolean bool2 = Character.isJavaIdentifierStart(c2);
  
        String str1 = "c1 may start a Java identifier is " + bool1;
        String str2 = "c2 may start a Java identifier is " + bool2;
  
        // Print bool1, bool2 values
        System.out.println(str1);
        System.out.println(str2);
    }
}


Output:

c1 may start a Java identifier is false
c2 may start a Java identifier is true

Reference: https://docs.oracle.com/javase/7/docs/api/java/lang/Character.html#isJavaIdentifierStart(char)



Last Updated : 06 Dec, 2018
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads