Java.lang。字符类方法 |设置 1

java.lang.Character 类方法

朗。字符类将原始数据类型 char 的值包装到数据类型 char 的对象中，并且该对象包含具有数据类型 char 的单个字段。这个类不提供。有关字符操作的方法，例如将它们从小写转换为大写。字符类是基于 Unicode 标准来提供字符信息的。
类声明：

public final class Character
   extends Object
      implements Serializable, Comparable

此处讨论字符类的以下方法：

charCount() : Java.lang.charCount()方法使用 Unicode 点返回 char 值的数量来表示参数 char 值。 Unicode 代码点用于 U+0000 和 U+10FFFF 范围内的字符值以及作为 UTF-16 编码的代码单元的 16 位字符值。
句法：
```
public static int charCount(int argchar)
Parameters : 
argchar : char i.e. it's Unicode point to be counted
Return : 
2 if the character is valid i.e. > or = to 0X1000(supplementary character); else 1   
```
charValue( ) : Java.lang.charValue()方法返回定义的 char 对象的原始字符值。
句法：
```
public char charValue()
Return : 
primitive character value of defined char Object.
```

codePointAt()： Java.lang。字符.codePointAt(char[ ] array, int position)方法返回参数位置存在的字符数组的 Unicode 点。
句法：

public static int codePointAt(char[] array, int position)
Parameters : 
array    : character array
position : array index of character whose Unicode Point value you need.  
Return : 
Unicode point of the character array present at the given position

解释使用 charCount()、charValue()、codePointat() 方法的Java代码

// Java program explaining Character class methods
// charCount(), charValue(), codePointat()
import java.lang.Character;
public class NewClass
{
    public static void main(String[] args)
    {
        // Use of charCount() method
        int geek = 0x9999,    // < 0x10000
            geek1 = 0x10000,      // = 0x10000
            geek2 = 0x10001;      // > 0x10000
  
        int check = Character.charCount(geek);
        int check1 = Character.charCount(geek1);
        int check2 = Character.charCount(geek2);
  
        if (check ==2)    // Checking for geek
            System.out.println("Valid Character geek");
        else
            System.out.println("Invalid Character geek");
  
        if (check1 ==2)   // Checking for geek1
            System.out.println("Valid Character geek1");
        else
            System.out.println("Invalid Character geek1");
  
        if (check2 ==2)   // Checking for geek2
            System.out.println("Valid Character geek2");
        else
            System.out.println("Invalid Character geek2");
  
        System.out.println("");
  
  
        // Use of charValue() method
        Character m;      // Character object m
  
        m = new Character('g');  // Assigning value g to m;
  
        char gfg;
        gfg = m.charValue();
        System.out.println("Primitive value of gfg : " +gfg);
        System.out.println("");
  
  
        // Use of codePointAt()
        char[] arg = new char[] { 'g', 'e', 'e', 'k', 's' };
        int val, val1, position  = 3;
  
        val = Character.codePointAt(arg, position);
        val1 = Character.codePointAt(arg, 0);
  
        System.out.println( "Unicode code point at " + position
                                                   + " : "+val );
        System.out.println( "Unicode code point at 0 : " + val1);
    }
}

输出：

Invalid Character geek
Valid Character geek1
Valid Character geek2

Primitive value of gfg : g

Unicode code point at 3 : 107
Unicode code point at 0 : 103

codePointBefore()： Java.lang。字符.codePointBefore(char[ ] array, int position)方法返回参数位置之前存在的字符数组的 Unicode 点。
句法：

public static int codePointBefore(char[] array, int position)
                          or
public static int codePointBefore(char[] array, int position, int start)
Parameters : 
array    : character array
position : array index of character following the Unicode Point value you need.  
start : start index of the character array
Return : 
Unicode point of the character array present before the given position

codePointCount()： Java.lang。字符.codePointCount()方法返回 no。子字符数组的Unicode点。
句法：

public static int codePointCount(char[] array, int start, int len)
Parameters : 
array  : character array
start  : starting index of the array
length : length of the character sub-array   
Return : 
no. of Unicode Point of the sub-character array.
Exception : 
--> NullPointerException
--> IndexOutOfBoundsException

compareTo()： Java.lang。字符.compareTo(字符 argChar)方法将给定的字符与参数的字符进行比较。
句法：

public int compareTo(Character argChar)
Parameters : 
argChar : character to be compared with  
Return : 
= 0 : if both characters are equal 
> 0 : if given this character is greater
< 0 : if argumented character is greater

解释 codePointBefore()、codePointCount()、compareTo() 方法使用的Java代码

// Java program explaining Character class methods
// codePointBefore(), codePointCount(), compareTo()
import java.lang.Character;
public class NewClass
{
    public static void main(String[] args)
    {
        // Use of codePointBefore()
        char[] arg = new char[] { 'g', 'e', 'e', 'k', 's' };
        int position  = 4;
  
        int val = Character.codePointBefore(arg, position);
        int val1 = Character.codePointBefore(arg, 1);
        int val2 = Character.codePointBefore(arg, 3, 1);
  
        System.out.println( "Unicode code point before " + position +
                                                       " : " + val );
        System.out.println( "Unicode code point before 1 : " + val1 );
        System.out.println( "Unicode code point before 3 to 1 : "
                                                              + val2);
        System.out.println("");
  
        // Use of codePointCount()
        int count = Character.codePointCount(arg, 1,3 );
  
        System.out.println("No. of Unicode points : " + count);
        System.out.println("");
  
        // Use of compareTo()
        Character g1 = new Character('g');
        Character g2 = new Character('o');
  
        int check = g1.compareTo(g2);
        System.out.println("g1 < g2 : " + check);
        int check1 = g2.compareTo(g1);
        System.out.println("g2 > g1 : " + check1);
        int check2 = g2.compareTo(g2);
        System.out.println("g2 = g2 : " + check2);
    }
}

输出：

Unicode code point before 4 : 107
Unicode code point before 1 : 103
Unicode code point before 3 to 1 : 101

No. of Unicode points : 3

g1  g1 : 8
g2 = g2 : 0

等于（）： Java.lang。字符.equals()方法将当前的 char 对象与参数化的 char 对象进行比较。
句法：

public boolean equals(Object charObj)
Parameters : 
charObj : char object to compare with 
Return : 
true if both the objects are equal, else false.

getNumericValue()： Java.lang。字符.getNumericValue(char arg)方法返回特定 Unicode字符的 int 值。
A – Z 值范围 u0041 到 u005A
a -z 值范围 u0061 到 u007A
句法：
```
public static int getNumericValue(char arg)
Parameters : 
arg : char value
Return : 
int value for the specific Unicode character.
if Unicode value doesn't exists -1 is returned.
```

getType()： Java.lang。字符.getType(char arg)方法识别字符的一般类型
A – Z 值范围 u0041 到 u005A
a -z 值范围 u0061 到 u007A
句法：

public static int getType(char arg)
Parameters : 
arg : char value
Return : 
int value for the argumented character representing its general type category.

Java代码解释了 equals()、getNumericValue()、getType() 方法的使用

// Java program explaining Character class methods
// equals(), getNumericValue(), getType()
import java.lang.Character;
public class NewClass
{
    public static void main(String[] args)
    {
        // Use of equals() method
        Character g1 = new Character('g');
        Character g2 = new Character('O');
  
        boolean check = g1.equals(g2);
        boolean check1 = g1.equals(g1);
        System.out.println("Are g and o equal? : " + check);
        System.out.println("Are g and g equal? : " + check1);
        System.out.println("");
  
        // Use of getNumericValue() method
        int c = Character.getNumericValue(g1);
        int c1 = Character.getNumericValue(g2);
        System.out.println("Int value for g : " + c);
        System.out.println("Int value for A : " + c1);
        System.out.println("");
  
        // Use of getType() method
        Character g3 = new Character('$');
        Character g4 = new Character('6');
  
        int r1 = Character.getType(g1);
        int r2 = Character.getType(g2);
        int r3 = Character.getType(g3);
        int r4 = Character.getType(g4);
  
        System.out.println("Type for lowercase : " + r1);
        System.out.println("Type for uppercase : " + r2);
        System.out.println("Type for currency  : " + r3);
        System.out.println("Type for numeric   : " + r4);
    }
}

输出：

Are g and o equal? : false
Are g and g equal? : true

Int value for g : 16
Int value for A : 24

Type for lowercase : 2
Type for uppercase : 1
Type for currency  : 26
Type for numeric   : 9