Character.isJavaIdentifierStart() method in Java
Last Updated :
06 Dec, 2018
The
java.lang.Character.isJavaIdentifierStart(char ch) is an inbuilt method in java which determines if the specified character is permissible as the first character in a Java identifier or not. A character may start as 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 ‘_’).
Note: This method cannot handle supplementary characters. To support all Unicode characters, including supplementary characters, use the isJavaIdentifierStart(int) method.
Syntax:
public static boolean isJavaIdentifierStart(char ch)
Parameters: The function accepts one mandatory parameter ch which specifies the character to be tested.
Return value: This method returns a boolean value. The boolean value is
True if the character may start a Java identifier,
False otherwise.
Program below demonstrates the Character.isJavaIdentifierStart(char ch) method:
Program 1:
Java
// Java program to demonstrate the
// Character.isJavaIdentifierStart()
import java.lang.*;
public class gfg {
public static void main(String[] args)
{
// create 2 char primitives c1, c2
char c1 = '9', c2 = '-';
// assign isJavaIdentifierStart results of c1, c2
// to boolean primitives bool1, bool2
boolean bool1 = Character.isJavaIdentifierStart(c1);
System.out.println(c1 + " may start a Java identifier is : " + bool1);
boolean bool2 = Character.isJavaIdentifierStart(c2);
System.out.println(c2 + " may start a Java identifier is : " + bool2);
}
}
Output:
9 may start a Java identifier is : false
- may start a Java identifier is : false
Program 2:
Java
// Java program to demonstrate the
// Character.isJavaIdentifierStart()
import java.lang.*;
public class gfg {
public static void main(String[] args)
{
// create 2 char primitives c1, c2
char c1 = '5', c2 = '_';
// assign isJavaIdentifierStart results of c1, c2
// to boolean primitives bool1, bool2
boolean bool1 = Character.isJavaIdentifierStart(c1);
System.out.println(c1 + " may start a Java identifier is : " + bool1);
boolean bool2 = Character.isJavaIdentifierStart(c2);
System.out.println(c2 + " may start a Java identifier is : " + bool2);
}
}
Output:
5 may start a Java identifier is : false
_ may start a Java identifier is : true
Reference: https://docs.oracle.com/javase/7/docs/api/java/lang/Character.html#isJavaIdentifierStart(char)
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