Java Character.isJavaIdentifierStart()用法及代碼示例

Character.isJavaIdentifierStart(int codePoint)是Java中的一種內置方法，它確定字符(Unicode代碼點)是否被允許作為Java標識符中的第一個字符。要注意的是，當且僅當以下條件之一為真時，字符才能開始Java標識符：

isLetter(ch)返回true
getType(ch)返回LETTER_NUMBER
ch是貨幣符號(例如“ $”)
ch是連接的標點字符(例如“ _”)。

用法:

public static boolean isJavaIdentifierStart(int codePoint)

參數：參數codePoint是整數類型，它表示要測試的字符(Unicode代碼點)。

返回值：如果字符可以啟動Java標識符，則Character類的isJavaIdentifierStart(int codePoint)方法返回true。否則為假。

以下示例程序旨在說明Character.isJavaIdentifierStart()方法：

示例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); 
    } 
}

輸出：

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

示例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); 
    } 
}

輸出：

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

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

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注：本文由純淨天空篩選整理自Twinkl Bajaj大神的英文原創作品 Character.isJavaIdentifierStart() Method in Java。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。