Character.isJavaIdentifierStart() Method in Java ❤️

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)

Character.isJavaIdentifierStart() Method in Java

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