java.lang.Character类方法| 1

作者: Arvin Chen 分类: Java 来源: Break易站(www.breakyizhan.com)
  •   Java 包装类

    java.lang.Character类方法| 1

    java.lang.Character类将原始数据类型的值 - char包装为数据类型为char的对象,并且此对象包含具有数据类型 - char的单个字段。这门课没有提供。有关字符操作的方法,如将它们从小写转换为大写。字符类基于Unicode标准提供字符信息。

    public final class Character
       extends Object
          implements Serializable, Comparable

    以下讨论Character类的以下方法:

    1. charCount():java.lang.charCount()方法使用Unicode 指针返回char值的数量来表示参数char值。Unicode代码点在U + 0000和U + 10FFFF之间和属于UTF-16编码的代码单元的16位char值的范围内用于字符的值。
      句法 :

      public static int charCount(int argchar)
       参数:
      argchar:char即它是统计的Unicode点
      返回: 
      2如果字符有效,即>或=到0X1000(补充字符); 其他1   
      
    2. charValue():java.lang.charValue()方法返回定义的char Object的原始字符值。
      句法 :

      public char charValue()
       返回:
      定义的char对象的原始字符值。
      
    3. codePointAt():java.lang.Character.codePointAt(char [] array,int position)方法返回存在于参数化位置的字符数组的Unicode Point。
      句法 :

      public static int codePointAt(char[] array, int position)
       参数:
      array:字符数组
      position:您需要的Unicode点值的字符的数组索引。  
      返回: 
      位于给定位置的字符数组的Unicode点  
      

    解释charCount(),charValue(),codePointat()方法使用的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
    1. codePointBefore():java.lang.Character.codePointBefore(char [] array,int position)方法返回提交位置前存在的字符数组的Unicode Point。
      句法 :

      public static int codePointBefore(char[] array, int position)
                                or
      public static int codePointBefore(char[] array, int position, int start)
      array:字符数组
      position:跟随您需要的Unicode点值的字符的数组索引。  
      start:字符数组的开始索引
      返回: 
      在给定位置之前存在的字符数组的Unicode点  
      
    2. codePointCount():java.lang.Character.codePointCount()方法返回no。子字符数组的Unicode Point。
      句法 :

      public static int codePointCount(char [] array,int start,int len)
       参数:
      array:字符数组
      start:数组的开始索引
      length:字符子数组的长度   
      返回: 
      no。子字符数组的Unicode Point。
      异常: 
      - > NullPointerException
      - > IndexOutOfBoundsException 
      
    3. compareTo():java.lang.Character.compareTo(Character argChar)方法将给定的字符与有争议的字符进行比较。
      句法 :

      public int compareTo(Character argChar)
       参数:
      argChar:与之相比的性格  
      返回: 
      = 0:如果两个字符相等 
      > 0:如果给出这个字符更大
      <0:如果争论角色更大
      

    说明使用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
    1. equals():java.lang.Character.equals()方法将当前的char对象与有争议的char对象进行比较。
      句法 :

      public boolean equals(Object charObj)
       参数:
      charObj:字符对象comapre 
      返回: 
      如果两个对象相等,则为true,否则为false。
      
    2. 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:

      public static int getNumericValue(char arg)
       参数:
      arg:char值
      返回: 
      特定Unicode字符的int值。
      如果Unicode值不存在则返回-1。
      
    3. getType():java.lang.Character.getType(char arg)方法标识字符的一般类型
      A - Z值范围u0041至u005A
      a -z值范围u0061至u007A
      语法:

      public static int getType(char arg)
       参数:
      arg:char值
      返回: 
      用于表示其一般类型类别的有争议字符的int值。 
      

    说明使用equals(),getNumericValue(),getType()方法的Java代码

    // 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
  •   Java 包装类
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