Java.lang Character

1 Java.lang Character介绍

Character类通常将所有基本类型char的值包装到一个对象中。字符类型的任何对象都可以包含一个类型为char的字段。

字符类的所有字段，方法和构造函数均由Unicode数据文件指定，该文件特别是Unicode字符数据库的一部分，并由Unicode联盟维护。

从U+0000到U+FFFF的一组字符有时被称为基本多语言平面（即BMP）。代码点大于U+FFFF的字符称为补充字符。Java语言通常使用UTF-16编码方法来表示String或String Buffer中的char数组。在这种表示形式中，辅助字符表示为一对字符，第一个字符来自高代理范围（\uD800-\uDBFF），第二个字符来自低代理范围（\uDc00-\uDBFF）。

2 Java.lang Character声明

public final class Character
   extends Object
      implements Serializable, Comparable<Character>

3 Java.lang Character方法

4 Java.lang Character案例1

package cn.xnip;

/**
 * 小牛知识库网： https://www.xnip.cn
 */
import java.util.Scanner;  
public class JavaCharacterExample1 {  
   public static void main(String[] args) {  
    // Ask the user for the first input.   
       System.out.print("Enter the first input:");  
    // Use the Scanner class to get the user input.  
       Scanner scanner = new Scanner(System.in);  
    // Gets the user input.  
       char[] value1 = scanner.nextLine().toCharArray();  
       int result1 = 0;  
    // Count the characters for a specific character.  
       for (char ch1 : value1) {  
       result1 = Character.charCount(ch1);  
       }  
    // Print the result.  
        System.out.print("The value comes to: "+result1+"\n");  
         
       System.out.print("Enter the second input:");  
       char[] value2 = scanner.nextLine().toCharArray();  
        for (char ch2 : value2) {  
        int result2 = Character.hashCode(ch2);  
       System.out.print("The hash code for the character '"+ch2+"' is given as:"+result2+"\n");  
       }  
      System.out.print("Enter the third input:");  
       char[] value3 = scanner.nextLine().toCharArray();  
       for (char ch3 : value3) {  
      boolean result3 = Character.isDigit(ch3);  
      if(result3){  
System.out.println("The character '" + ch3 + "' is a digit. ");               
                }  
      else{  
System.out.println("The character '" + ch3 + "' is not a digit.");  
           }      
      System.out.print("Enter the fourth input:");  
       char[] value4 = scanner.nextLine().toCharArray();  
       for (char ch4 : value4) {  
      boolean result4 = Character.isISOControl(ch4);  
      System.out.println("The fourth character '"+ch4+"' is an ISO Control:"+result4);                
         }  
       }  
   }  
} 

输出结果为：

Enter the first input:89
The value comes to: 1
Enter the second input:J
The hash code for the character 'J' is given as:74
Enter the third input:5
The character '5' is a digit. 
Enter the fourth input:h
The fourth character 'h' is an ISO Control:false

5 Java.lang Character案例2

public class JavaCharacterExample2{  
 public static void main(String[] args) {  
      // Create four char primitives ch1, ch2, ch3 and ch4.  
         char ch1, ch2, ch3, ch4;  
      // Assign the values to ch1, ch2, ch3 and ch4.  
         ch1 = 'T';  
         ch2 = 'k';  
         ch3 = '\n';  
         ch4 = 'G';  
      // Create four boolean primitives b1, b2, b3 and b4.  
      boolean b1, b2, b3,b4;  
      // Assign the results to b1, b2, b3 and b4.  
      b1 = Character.isLetter(ch1);  
      b2 = Character.isLowerCase(ch2);  
      b3 = Character.isSpace(ch3);  
      b4 = Character.isDefined(ch3);  
      String str1 = " The first character is a letter: " + b1;  
      String str2 = " The second character is a lower-case: " + b2;  
      String str3 = " The third character is for space: " + b3;  
      String str4 = " The fourth character is defined in Java identifier: " + b3;  
      // Print the values of b1, b2, b3 and b4.  
      System.out.println( str1 );  
      System.out.println( str2 );  
      System.out.println( str3 );  
      System.out.println( str3 );  
   }  
}  

输出结果为：

The first character is a letter: true
The second character is a lower-case: true
The third character has a space: true
The third character has a space: true