Java中的字符.isJavaIdentifierStart() 方法
字符.isJavaIdentifierStart(int codePoint)是Java中的一个内置方法,用于确定字符(Unicode 代码点)是否允许作为Java标识符中的第一个字符。需要注意的是,当且仅当以下条件之一为真时,字符才可以开始Java标识符:
- isLetter(ch) 返回真
- getType(ch) 返回 LETTER_NUMBER
- ch 是货币符号(例如'$')
- ch 是连接标点符号(例如“_”)。
句法:
public static boolean isJavaIdentifierStart(int codePoint)
参数:参数codePoint是整数类型,指的是要测试的字符(Unicode码位)。
返回值:如果字符可以开始一个Java标识符, 字符类的isJavaIdentifierStart(int codePoint)方法返回true;否则为假。
下面的程序说明了字符.isJavaIdentifierStart() 方法:
方案一:
// 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);
}
}
输出:
c1 may start a Java identifier is false
c2 may start a Java identifier is true
c3 may start a Java identifier is false
方案二:
// 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);
}
}
输出:
c1 may start a Java identifier is false
c2 may start a Java identifier is true
参考:https: Java/lang/ 字符.html#isJavaIdentifierStart(char)