CharArrayWriter class methods in Java

java.io.CharArrayWriter

This class implements a character buffer that can be used as a Writer. The buffer automatically grows when data is written to the stream.

Note: The data can be retrieved using toCharArray() and toString().

Some methods of CharArrayWriter class.

append(char): This method appends the specified character to this writer.

append(CharSequence): This method appends the specified character sequence to this writer.

append(CharSequence, int, int): This method appends a subsequence of the specified character sequence to this writer.

close(): This method does not release the buffer, since its contents might still be required.

flush(): This method flushes the stream.

reset(): This method resets the buffer so that you can use it again without throwing away the already allocated buffer.

size(): This method returns the current size of the buffer.

toCharArray(): This method returns a copy of the input data.

toString(): This method converts input data to a string.

write(int): This method writes a character to the buffer.

write(char[], int, int): This method writes characters to the buffer.

write(String, int, int): This method writes a portion of a string to the buffer.

writeTo(Writer): This method writes the contents of the buffer to another character stream.

CharArrayWriter writeTo(Writer) in Java

writeTo(Writer): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

void java.io.CharArrayWriter.writeTo(Writer out) throws IOException

This method takes one argument. This method writes the contents of the buffer to another character stream.

Parameters: One parameter is required for this method.

out: the output stream to write to.

Returns: NA

Throws: IOException - If an I/O error occurs.

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterwriteTo {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        CharArrayWriter out = new CharArrayWriter();
        charArrayWriter.writeTo(out);

        System.out.println(out.toString());
        charArrayWriter.close();
    }
}

Output:

abcd

CharArrayWriter write(String, int, int) in Java

write(String, int, int): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

void java.io.CharArrayWriter.write(String str, int off, int len)

This method takes three arguments. This method writes a portion of a string to the buffer.

Parameters: Three parameters are required for this method.

str: String to be written from.

off: Offset from which to start reading characters.

len: Number of characters to be written.

Throws:

IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given string

Approach 1: When no exception

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterwrite3 {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        int off = 1, len = 3;
        String str = "HELLO";
        charArrayWriter.write(str, off, len);

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

abcdELL

Approach 2: IndexOutOfBoundsException 

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterwrite3 {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        int off = -1, len = 3;
        String str = "HELLO";
        charArrayWriter.write(str, off, len);

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: begin -1, end 2, length 5
	at java.base/java.lang.String.checkBoundsBeginEnd(String.java:3734)
	at java.base/java.lang.String.getChars(String.java:873)
	at java.base/java.io.CharArrayWriter.write(CharArrayWriter.java:133)
	

CharArrayWriter write(char[], int, int) in Java

write(char[], int, int): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

void java.io.CharArrayWriter.write(char[] c, int off, int len)

This method takes three arguments. This method writes characters to the buffer.

Parameters: Three parameters are required for this method.

c: the data to be written.

off: the start offset in the data.

len: the number of chars that are written.

Returns: NA

Throws:

IndexOutOfBoundsException - If off is negative, or len is negative, or off + len is negative or greater than the length of the given array

Approach 1: When no exception

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterwrite2 {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        int off = 1, len = 2;
        charArrayWriter.write(cbuf, off, len);

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

abcdbc

Approach 2: IndexOutOfBoundsException

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterwrite2 {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        int off = -1, len = 2;
        charArrayWriter.write(cbuf, off, len);

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

Exception in thread "main" java.lang.IndexOutOfBoundsException
	at java.base/java.io.CharArrayWriter.write(CharArrayWriter.java:102)
	

CharArrayWriter write(int) in Java

write(int): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

void java.io.CharArrayWriter.write(int c)

This method takes one argument. This method writes a character to the buffer.

Parameters: One parameter is required for this method.

c: int specifying a character to be written.

Returns: NA

Exceptions: NA

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterwrite {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        int c = 'M';
        charArrayWriter.write(c);

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

abcdM

CharArrayWriter toString() in Java

toString(): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

String java.io.CharArrayWriter.toString()

This method converts input data to a string.

Parameters: NA

Returns: the string.

Exceptions: NA

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWritertoString {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

abcd

CharArrayWriter toCharArray() in Java

toCharArray(): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

char[] java.io.CharArrayWriter.toCharArray()

This method returns a copy of the input data.

Parameters: NA

Returns: an array of chars copied from the input data.

Exceptions: NA

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;
import java.util.Arrays;

public class CharArrayWritertoCharArray {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        System.out.println(Arrays.toString(
                            charArrayWriter.toCharArray()));
        charArrayWriter.close();
    }
}

Output:

[a, b, c, d]

CharArrayWriter size() in Java

size(): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

int java.io.CharArrayWriter.size()

This method returns the current size of the buffer.

Parameters: NA

Returns: an int representing the current size of the buffer.

Exceptions: NA

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWritersize {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        System.out.println(charArrayWriter.size());
        charArrayWriter.close();
    }
}

Output:

4

CharArrayWriter reset() in Java

reset(): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

void java.io.CharArrayWriter.reset()

This method resets the buffer so that you can use it again without throwing away the already allocated buffer.

Parameters: NA

Returns: NA

Exceptions: NA

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterreset {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        charArrayWriter.reset();

        System.out.println("Successfully reset");
        charArrayWriter.close();
    }
}

Output:

Successfully reset

CharArrayWriter flush() in Java

flush(): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

void java.io.CharArrayWriter.flush()

This method flushes the stream.

Parameters: NA

Returns: NA

Exceptions: NA

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterflush {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        charArrayWriter.flush();

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

abcd

CharArrayWriter close() in Java

close(): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

void java.io.CharArrayWriter.close()

This method closes the stream. This method does not release the buffer, since its contents might still be required.

Parameters: NA

Returns: NA

Exceptions: NA

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterclose {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

abcd

CharArrayWriter append(CharSequence, int, int) in Java

append(CharSequence, int, int): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

CharArrayWriter java.io.CharArrayWriter.append(CharSequence csq, int start, int end)

This method takes three arguments. This method appends a subsequence of the specified character sequence to this writer.

Parameters: Three parameters are required for this method.

csq: The character sequence from which a subsequence will be appended. If csq is null, then characters will be appended as if csq contained the four characters "null".

start: The index of the first character in the subsequence.

end: The index of the character following the last character in the subsequence.

Returns: This writer.

Throws:

IndexOutOfBoundsException - If start or end is negative, the start is greater than the end, or end is greater than csq.length().

Approach 1: When no exception

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterappend3 {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        CharSequence csq = "ABCD";
        int start = 1, end = 3;
        charArrayWriter.append(csq, start, end);

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

abcdBC

Approach 2: IndexOutOfBoundsException 

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterappend3 {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c', 'd' };
        charArrayWriter.write(cbuf);

        CharSequence csq = "ABCD";
        int start = -1, end = 3;
        charArrayWriter.append(csq, start, end);

        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: begin -1, end 3, length 4
	at java.base/java.lang.String.checkBoundsBeginEnd(String.java:3734)
	at java.base/java.lang.String.substring(String.java:1903)
	at java.base/java.lang.String.subSequence(String.java:1942)
	at java.base/java.io.CharArrayWriter.append(CharArrayWriter.java:215)
	

CharArrayWriter append(CharSequence) in Java

append(CharSequence): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

CharArrayWriter java.io.CharArrayWriter.append(CharSequence csq)

This method takes one argument. This method appends the specified character sequence to this writer.

Parameters: One parameter is required for this method.

csq: The character sequence to append.

Note: If csq is null, then the four characters "null" are appended to this writer.

Returns: This writer.

Exceptions: NA

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterappend2 {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c' };
        charArrayWriter.write(cbuf);

        CharSequence csq = "ABCD";
        charArrayWriter.append(csq);
        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

abcABCD

CharArrayWriter append(char) in Java

append(char): This method is available in the java.io.CharArrayWriter class of Java.

Syntax:

CharArrayWriter java.io.CharArrayWriter.append(char c)

This method takes one argument. This method appends the specified character to this writer.

Parameters: One parameter is required for this method.

c: The 16-bit character to append.

Returns: This writer.

Exceptions: NA

Approach

Java

import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterappend {
    public static void main(String[] args) throws IOException {
        CharArrayWriter charArrayWriter = new CharArrayWriter();

        char cbuf[] = { 'a', 'b', 'c' };
        charArrayWriter.write(cbuf);

        char c = 'd';
        charArrayWriter.append(c);
        System.out.println(charArrayWriter.toString());
        charArrayWriter.close();
    }
}

Output:

abcd

CharArrayReader class methods in Java

java.io.CharArrayReader

This class implements a character buffer that can be used as a character-input stream.

Some methods of CharArrayReader class.

 close(): This method closes the stream and releases any system resources associated with it.

mark(int): This method marks the present position in the stream.

markSupported(): This method tells whether this stream supports the mark() operation, which it does.

read(): This method reads a single character.

read(char[], int, int): This method reads characters into a portion of an array.

ready(): This method tells whether this stream is ready to be read.

reset(): This method resets the stream to the most recent mark, or to the beginning if it has never been marked.

skip(long): This method skips characters. Returns the number of characters that were skipped.