java.lang.Character 类方法|集合 1
原文:https://www . geesforgeks . org/Java-lang-character-class-methods-set-1/
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。这个类提供了许多关于字符操作的方法，比如把它们从小写转换成大写。字符类基于 Unicode 标准提供字符信息。 类申报:
public final class Character
extends Object
implements Serializable, Comparable
下面讨论字符类的方法:
-
char count():Java . lang . char count()方法使用 Unicode point 返回字符值的个数来表示参数字符值。一个 Unicode 码位用于 U+0000 到 U+10FFFF 范围内的字符值，以及作为 UTF-16 编码的编码单位的 16 位字符值。 语法:
```java 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()方法返回已定义 char Object 的原始字符值。 语法:
```java public char charValue() Return : primitive character value of defined char Object.
```
-
codePointAt() : java.lang.Character.codePointAt(char[ ] array, int position) method returns Unicode Point of the character array present at the argumented position. Syntax :
```java 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 // 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:
```java 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
```
-
codepoint before():Java . lang . character . codepoint before(char[]数组，int 位置)方法返回出现在参数化位置之前的字符数组的 Unicode 点。 语法:
```java 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 . character . codePointCount()方法返回子字符数组的 Unicode 点数。 语法:
```java 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```
-
compare to():Java . lang . Character . compare to(Character argChar)方法将给定的字符与有争议的字符进行比较。 语法:
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
解释使用 codePointBefore()、codePointCount()、compareTo()方法的 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
-
equals():Java . lang . character . equals()方法将当前 char 对象与参数化 char 对象进行比较。 语法:
```java 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 . character . getNumericValue(char arg)方法返回特定 Unicode 字符的 int 值。 A–Z 值范围 u0041 至 u005A a -z 值范围 u0061 至 u007A 语法:
```java 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.Character.getType(char arg) method identifies the general type of character A – Z value ranges u0041 to u005A a -z value ranges u0061 to u007A Syntax :
```java public static int getType(char arg) Parameters : arg : char value Return : int value for the argumented character representing its general type category.
```
'
解释 equals()，getNumericValue()，getType()方法使用的 Java 代码
```java // 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('{content}apos;); 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:
```java 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
```
本文由 莫希特·古普塔 供稿。如果你喜欢 GeeksforGeeks 并想投稿，你也可以使用write.geeksforgeeks.org写一篇文章或者把你的文章邮寄到 review-team@geeksforgeeks.org。看到你的文章出现在极客博客主页上，帮助其他极客。
如果你发现任何不正确的地方，或者你想分享更多关于上面讨论的话题的信息，请写评论。
版权属于：月萌API www.moonapi.com，转载请注明出处
