Java Character isDefined()用法及代碼示例

Character 類的 isDefined(char ch) 方法一般判斷該字符是否在 Unicode 中定義。

當且僅當滿足以下兩個條件中的任何一個(或為真)時，才在 Unicode 中定義字符：

該字符必須在 UnicodeData 文件中有一個條目。
字符必須有一個由 UnicodeData 文件定義的範圍。

用法

public static Boolean isDefined(char ch)

參數

上述方法隻需要一個參數：

a.) 需要測試的字符。

返回值

如果給定(或指定)字符在 Unicode 中具有定義的含義，則 isDefined(char ch) 方法返回一個布爾值，即 true。否則，它返回 false。

例子1

public class JavaCharacterisDefinedExample1 {
    public static void main(String[] args) {
          // Create char primitives obj1, obj2 and obj3
          char obj1;
          char obj2;
          char obj3;
          // Assign the values to obj1, obj2 and obj3.
          obj1 = '@';
          obj2 = '*';
          obj3 = '&';
          // Create the boolean primitives b1, b2,b3.
          boolean b1;
          boolean b2;
          boolean b3;
          b1 = Character.isDefined(obj1);
          b2 = Character.isDefined(obj2);
          b3 = Character.isDefined(obj3);
          String str1 = "The meaning for the character " +obj1+ " is defined as: " +b1;
          String str2 = "The meaning for the character " +obj2+ " is defined as: " +b2;
          String str3 = "The meaning for the character " +obj3+ " is defined as:  " +b3;
          // print b value
          System.out.println( str1 );
          System.out.println( str2 );
          System.out.println( str3 );
       }
    }

輸出：

The meaning for the character @ is defined as: true
The meaning for the character * is defined as: true
The meaning for the character & is defined as: true

例子2

import java.util.Scanner;
public class JavaCharacterisDefinedExample2 {
public static void main(String[] args) {
     // Ask the user to enter the first character.
    System.out.print("Enter a character:  ");		
    // Use scanner to get the user input
    Scanner obj1 = new Scanner(System.in);
   // get a single character
    char value1 = obj1.nextLine().toCharArray()[0];
        
    // Check whether the user input is defined the Unicode or not.
    boolean check1 = Character.isDefined(value1);
   // Print the result
    if(check1){
System.out.print("The user input \'"+value1+"\' is defined in the Unicode\n");
        }
    else{
System.out.print("The user input \'"+value1+"\' is not defined in the Unicode\n");
        }
   // Ask the user to enter the second character.
System.out.print("Enter the second character:  ");				
  // Use scanner to get the user input
    Scanner obj2 = new Scanner(System.in);
  // get a single character
    char value2 = obj2.nextLine().toCharArray()[0];			
  // Check whether the user input is defined the Unicode or not. 
    boolean check2 = Character.isDefined(value2);
  // Print the result
     if(check2){
System.out.print("The user input \'"+value2+"\' is defined in the Unicode");
       }
     else{
System.out.print("The user input \'"+value2+"\' is not defined in the Unicode");
        }		
       }
}

輸出：

Enter a character:  $
The user input '$' is defined in the Unicode
Enter the second character:  )
The user input ')' is defined in the Unicode

例子3

public class JavaCharacterisDefinedExample3 {
    public static void main(String args[])
      {
       char ch1 = '1';
       char ch2 = '2';    
       char ch3 = '3';    
       char ch4 = '4';    
       char ch5 = '5';   
       boolean b1 = Character.isDefined(ch1);
       boolean b2 = Character.isDefined(ch2);
       boolean b3 = Character.isDefined(ch3);
       boolean b4 = Character.isDefined(ch4);
       boolean b5 = Character.isDefined(ch5);
System.out.println(ch1 + " is defined in the Unicode character set:" + b1);              
System.out.println(ch2 + " is defined in the Unicode character set:" + b2);  
System.out.println(ch3 + " is defined in the Unicode character set:" + b3);  
System.out.println(ch4 + " is defined in the Unicode character set:" + b4);   
System.out.println(ch5 + " is defined in the Unicode character set:" + b5); 
     	}
}

輸出：

1 is defined in the Unicode character set:true
2 is defined in the Unicode character set:true
3 is defined in the Unicode character set:true
4 is defined in the Unicode character set:true
5 is defined in the Unicode character set:true

相關用法

注：本文由純淨天空篩選整理自 Java Character isDefined() Method。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。