Java Java类

Java .io.CharArrayReader类使用字符数组创建字符缓冲区。

宣言：

public class CharArrayReader
   extends Reader

构造函数：

• CharArrayReader(char[] char_array) ：从指定的字符数组创建一个 CharArrayReader。
• CharArrayReader(char[] char_array, int offset, int maxlen) ：从字符数组的指定部分创建一个 CharArrayReader。

方法：

• read() : Java.io.CharArrayReader.read()读取单个字符并在到达 Stream 末尾时返回 -1。
  句法 ：

public int read()
Parameters : 
-----------
Return  :
Returns read character as an integer ranging from range 0 to 65535.
-1 : when end of file is reached.

• read(char[] char_array, int offset, int maxlen) : Java.io.CharArrayReader.read(char[] char_array, int offset, int maxlen))读取单个字符并在到达 Stream 末尾时返回 -1
  句法 ：

public int read(char[] char_array, int offset, int maxlen))
Parameters : 
char_array : destination array  
offset : starting position from where to store characters
maxlen : maximum no. of characters to be read
Return  :
Returns all the characters read
-1 : when end of file is reached.

• ready() : Java.io.CharArrayReader.ready()检查 Stream 是否准备好被读取。
  CharArrayReader 始终准备好被读取。
  句法 ：

public boolean ready()
Parameters : 
-----------
Return  :
true if CharArrayReader is ready to be read.

• skip(long char) : Java.io.CharArrayReader.skip(long char_no)跳过'char_no' no。字符。如果 n 为负数，则此方法不执行任何操作并返回 0。
  句法 ：

public long skip(long char)
Parameters : 
char_no : char no. of characters to be skipped
Return  :
no. of characters skipped
Exception : 
IOException : In case of I/O error occurs

Java

// Java program illustrating the working of CharArrayReader class methods
// read(), skip(), ready()
// read(char[] char_array, int offset, int maxlen)
 
import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
 
        // Initializing the character array
        char[] geek = {'G', 'E', 'E', 'K', 'S'};
 
        // Initializing the char_array
        CharArrayReader char_array1 = new CharArrayReader(geek);
        CharArrayReader char_array2 = new CharArrayReader(geek);
 
        // Use of ready() method
        boolean check1 = char_array1.ready();
        if(check1 ==true)
            System.out.println("char_array1 is ready");
        else
            System.out.println("char_array1 is not ready");
 
 
        int a = 0;
        System.out.print("Use of read() method : ");
        // Use of read() method : reading each character one by one
        while((a = char_array1.read()) != -1)
        {
            char c1 = (char)a;
            System.out.println(c1);
 
            // Use of skip() method
            long char_no = char_array1.skip(1);
            System.out.println("Characters Skipped : "+(c1+1));
 
        }
        System.out.println("");
 
 
        // Use of ready() method
        boolean check2 = char_array2.ready();
        if(check2 ==true)
            System.out.println("char_array2 is ready");
        else
            System.out.println("char_array2 is not ready");
 
 
  // Use of read(char[] char_array, int offset, int maxlen) : reading a part of array
        char_array2.read(geek, 1, 2);
 
        int b = 0;
 
  System.out.print("Use of read(char[] char_array, int offset, int maxlen) method : ");
 
        while((b = char_array2.read()) != -1)
        {
            char c2 = (char)b;
            System.out.print(c2);
        }
 
    }
}

输出 ：

char_array1 is ready
Use of read() method : G
Characters Skipped : 72
E
Characters Skipped : 70
S
Characters Skipped : 84

char_array2 is ready
Use of read(char[] char_array, int offset, int maxlen) method : EKS

• mark(int readLimit) : Java.io.CharArrayReader.mark(int readLimit)标记 Stream 中可以读取字符的当前位置。此方法始终调用 reset() 方法。对 reset() 的后续调用会将流重新定位到该点。
  句法 ：

public long mark(int readLimit)
Parameters : 
readLimit : No. of characters that can be read up to the mark
Return  :
void
Exception : 
IOException : In case of I/O error occurs

• markSupported() : Java.io.CharArrayReader.markSupported()告诉流是否支持标记方法。
  句法 ：

public boolean markSupported()
Parameters : 
-------
Return  :
true if the mark method is supported by the stream
Exception : 
IOException : In case of I/O error occurs

• reset() : Java.io.CharArrayReader.reset()将流重置为最近的标记，如果从未标记，则重置为开头。
  句法 ：

public void reset()
Parameters : 
-------
Return  :
void
Exception : 
IOException : In case of I/O error occurs

• close() : Java.io.CharArrayReader.close()关闭流并重新分配分配给它的资源。
  句法 ：

public void close()
Parameters : 
-------
Return  :
void
Exception : 
IOException : In case of I/O error occurs

Java

// Java program illustrating the working of FilterInputStream method
// mark(), reset()
// markSupported(), close()
 
import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws Exception
    {
        // Initializing CharArrayReader
        CharArrayReader char_array = null;
        char[] geek = {'H', 'E', 'L', 'L', 'O', 'G',  'E',  'E',  'K', 'S'};
 
        try
        {
            char_array = new CharArrayReader(geek);
 
            // read() method : reading and printing Characters
            // one by one
            System.out.println("Char : "+(char)char_array.read());
            System.out.println("Char : "+(char)char_array.read());
            System.out.println("Char : "+(char)char_array.read());
 
            // mark() : read limiting the 'geek' input stream
            char_array.mark(0);
 
            System.out.println("mark() method comes to play");
            System.out.println("Char : "+(char)char_array.read());
            System.out.println("Char : "+(char)char_array.read());
            System.out.println("Char : "+(char)char_array.read());
 
            // Use of markSupported() :
            boolean check = char_array.markSupported();
            if (check == true )
                System.out.println("mark() supported\n");
 
            if (char_array.markSupported())
            {
                // reset() method : repositioning the stream to
                // marked positions.
                char_array.reset();
                System.out.println("reset() invoked");
                System.out.println("Char : "+(char)char_array.read());
                System.out.println("Char : "+(char)char_array.read());
            }
            else
                System.out.println("mark() method not supported.");
             
        }
        catch(Exception excpt)
        {
            // in case of I/O error
            excpt.printStackTrace();
        }
        finally
        {
            // Use of close() : releasing the resources back to the
            // GarbageCollector when closes
            if(char_array != null)
                char_array.close();
        }
    }
}

输出 ：

Char : H
Char : E
Char : L
mark() method comes to play
Char : L
Char : O
Char : G
mark() supported

reset() invoked
Char : L
Char : O