Java.io.CharArrayReader Class in Java - GeeksforGeeks

18 Apr, 2022
java.io.CharArrayReader class creates a character buffer using a character array.
Declaration: 
public class CharArrayReader
   extends Reader
Constructor :  
CharArrayReader(char[] char_array) : Creates a CharArrayReader from a specified character array.
CharArrayReader(char[] char_array, int offset, int maxlen) : Creates a CharArrayReader from a specified part of character array.
Methods:  
read() : java.io.CharArrayReader.read() reads a single character and returns  -1 if end of the Stream is reached. Syntax : 
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)) reads a single character and returns -1 if end of the Stream is reached Syntax : 
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() checks whether the Stream is ready to be read or not. CharArrayReader are always ready to be read. Syntax : 
public boolean ready()
Parameters : 
-----------
Return  :
true if CharArrayReader is ready to be read.
skip(long char) : java.io.CharArrayReader.skip(long char_no) skips ‘char_no’ no. of characters.  If n is negative, then this method does nothing and returns 0. Syntax : 
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);        }     }}
Output : 
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) marks the current position in the Stream upto which the character can be read. This method always invokes reset() method. Subsequent calls to reset() will reposition the stream to this point. Syntax : 
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() tells whether the mark method is supported by the stream or not. Syntax : 
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() Resets the stream to the most recent mark, or to the beginning if it has never been marked. Syntax : 
public void reset()
Parameters : 
-------
Return  :
void
Exception : 
IOException : In case of I/O error occurs
close() : java.io.CharArrayReader.close() closes the stream and reallocates the resources that were allotted to it. Syntax : 
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();        }    }}
Output : 
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
This article is contributed by Mohit Gupta . If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. 
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