Java CharArrayWriter Class

The Java.io.CharArrayWriter class implements a character buffer that can be used as a Writer. Data written to the stream automatically expands the buffer.

Explanation

The CharArrayWriter class is a subclass of the Writer abstract class. Its purpose is to write characters from a char array to a buffer that is also a char array and then from this buffer to a character stream.

Syntax

public class CharArrayWriter extends Writer

Constructor

• CharArrayWriter()
  With the given array of characters, a CharArrayReader is created.
• CharArrayWriter(int initialSize)
  Using the given initial size generates a new CharArrayWriter.

Method

• CharArrayWriter append(char c)
  The specified character is appended to this writer by this method.CharArrayWriter append(CharSequence csq)The given character sequence is appended to this writer by this method.
• CharArrayWriter append(CharSequence csq, int start, int end)
  This method adds a subsequence of the given character sequence to this writer.
• void close()
  This technique ends the stream.
• voidFlush()
  This technique clears the stream.
• void reset()
  This method resets the buffer, allowing you to use it again without wasting the previously allocated buffer.
• Int size()
  This method returns the buffer’s current size.
• char[] toCharArray()
  This method returns a copy of the input data.
• String toString()
  This technique creates a string out of the input data.
• void write(char[] c, int off, int len)
  Writes characters to the buffer using this method.
• void write(int c)
  Write a character to the buffer using this method.
• void write(String str, int off, int len)
  Using this method, a string section is written to the buffer.
• void writeTo(Writer out)
  The contents of the buffer are written to a different character stream using this method.

Field

• protected char[] buf
  This is the buffer used to hold data.
• protected int count
  This is the buffer’s character count.
• protected Object lock
  This is the object that keeps this stream’s operations in sync.

Type	Method	Description
CharArrayWritter	append(char c)	Adds this writer’s specified character.
CharArrayWritter	append(CharSequence csq)	Appends to this writer the designated character sequence.
CharArrayWritter	append(CharSequence csq, int start, int end)	Attached is a portion of the designated character sequence for this writer.
void	close()	It shutdown the stream
void	flush()	Make the stream run.
void	Reset()	Resetting the buffer allows you to utilize it once more without wasting the previously allocated space.
int	Size()	Gives back the buffer’s current size.
char[]	toCharArray()	Gives back a duplicate of the input data.
string	toString()	converts the data input to a string.
Void	write(char[] c, int off, int len)	It enters the buffer with characters.
void	write(int c)	A character is written to the buffer.
void	writeTo(Writer out)	Writes the buffer’s contents to a different character stream.

Example

package studytonight;
import java.io.CharArrayWriter;
import java.io.FileWriter;
public class StudyTonight 
{
  public static void main(String args[]) throws Exception
  {
    CharArrayWriter writer=new CharArrayWriter();    
    writer.write("Hello Studytonight");    
    FileWriter fileWriter=new FileWriter("E:\studytonight\\output.txt");   
    writer.writeTo(fileWriter);    
    fileWriter.close();    
    System.out.println("Data is written successfully...");    
  }
}

Output
Data is written successfully…

Example

import java.io.*;
class A
{
public static void main(String... ar)
{
char[] arr1= new char[]{'j','a','v','a'};
char[] arr2= new char[]{'p','r','o','g','r',’a’,’m’};

try
{
CharArrayWriter caw= new CharArrayWriter(); 
System.out.println("Initial Size of the buffer = "+ caw.size());

for(char ch : arr1) 
{
caw.write(ch);
}

caw.write(arr2);  

System.out.println("Content of buffer = "+ caw.toString());
System.out.println("Size of the buffer = "+ caw.size());

FileWriter fw = new FileWriter("D:\\TextBook2.txt");
caw.writeTo(fw);

fw.flush();
caw.flush();
caw.close();
}		 	 
catch(IOException e)
{
System.out.println(e);
}

}
}

Output
Initial Size of the buffer = 0
Content of buffer = javaprogram
Size of the buffer = 13

Conclusion

Using the Char array writer class, we can write shared data to several files. This class creates a buffer for writing data. When data is written to the stream, this buffer expands automatically and has no set size.