Java.io.Writer Class in Java

java.io.Writer class is an abstract class. It is used to write to character streams.

Declaration of Writer Class in Java

public abstract class Writer
  extends Object
    implements Appendable, Closeable, Flushable

Constructors of Java Writer Class

• protected Writer(): Creates a new character stream that can itself synchronize on the writer.
• protected Writer(Object obj): Creates a new character stream that can itself synchronize on the given object – ‘obj’.

Methods of Java Writer Class

There are certain methods associated with the Java Writer class as mentioned below:

Method	Description
append(char SW)	appends a single character to the writer
append(CharSequence char_sq)	appends specified character sequence to the writer
append(CharSequence char_sq,int start,int end)	appends specified part of the character sequence to the writer
flush()	flushes the writer stream. Flushing one stream invocation will flush all the other buffers in chains.
write(int char)	write a single character to the character stream.
write(string str)	write a string to the character stream.
write(string str, int offset , int maxlen)	writes some part of the string to the character string.
write(char[] carray)	writes character array to the character stream.
write(char[] carray, int offset, int maxlen)	writes some part of the character array to the character stream.
close()	closes String Buffer. Since, closes the character stream, flushing it first.

1. write(int char) 

 java.io.Writer.write(int char) writes a single character to the character stream. Characters being written are contained in 16 lower bits of the ‘char’ integer value, the rest of the 16 higher bits are ignored by the method. 

Syntax: public void write(int char)

Parameters : 
char : int value of the character to be written.

Return  :
void

Exception :
-> IOException : if in case I/O error occurs.

2. write(String str) :

java.io.Writer.write(String str) writes a string to the character stream. 

Syntax: public void write(String str)

Parameters : 
str : string to be written to the character stream.

Return  :
void

Exception :
-> IOException : if in case I/O error occurs.

3. write(String str, int offset, int maxlen) 

java.io.Writer.write(String str, int offset, int maxlen) writes some part of the string to the character stream. 

Syntax: public void write(String str, int offset, int maxlen)

Parameters : 
str : string to be written to the character stream.
offset : start position of the String
maxlen : maximum length upto which string has to written

Return  :
void

Exception :
-> IOException : if in case I/O error occurs.
-> IndexOutOfBoundsException : if offset is -ve or offset + maxlen = -ve || > maxlen 

4. write(char[] carray) 

java.io.Writer.write(char[] carray) writes character array to the character stream. 

Syntax: public void write(char[] carray)

Parameters : 
carray : character array to be written to the character stream

Return  :
void

Exception :
-> IOException : if in case I/O error occurs. 

5. write(char[] carray, int offset, int maxlen)

java.io.Writer.write(char[] carray, int offset, int maxlen) writes some part of the character array to the character stream. 

Syntax: public abstract void write(char[] carray, int offset, int maxlen)

Parameters : 
carray : character to be written to the character stream
offset : start position of the character array
maxlen : maximum no. of the character of the carray has to written

Return  :
void

Exception :
-> IOException : if in case I/O error occurs.

6. close()

java.io.Writer.close() closes the character stream, flushing it first. 

Syntax: public abstract void close()

Parameters : 
-----------

Return  :
void

Exception :
-> IOException : if in case I/O error occurs. 

7. flush()

 java.io.Writer.flush() flushes the Writer stream. Flushing one stream invocation will flush all other buffer in chain. 

Syntax: public void flush()

Parameters : 
-----

Return  :
void

Exception :
-> IOException : if in case I/O error occurs.

8. append(char Sw)

java.io.Writer.append(char Sw) appends a single character to the Writer. 

Syntax: public Writer append(char Sw)

Parameters : 
Sw : character to be append

Return  :
Writer

Exception :
-> IOException : if in case I/O error occurs.

9. append(CharSequence char_sq) 

 java.io.Writer.append(CharSequence char_sq) appends specified character sequence to the Writer. 

Syntax: public Writer append(CharSequence char_sq)

Parameters : 
char_sq : Character sequence to append. 

Return  :
Writer, if char sequence is null, then NULL appends to the Writer.

Exception :
-> IOException : if in case I/O error occurs. 

10. append(CharSequence char_sq, int start, int end)

java.io.Writer.append(CharSequence char_sq, int start, int end) appends specified part of a character sequence to the Writer. 

Syntax: public Writer append(CharSequence char_sq, int start, int end)

Parameters : 
char_sq : Character sequence to append.
start : start of character in the Char Sequence
end : end of character in the Char Sequence

Return  :
void

Exception :
-> IOException : if in case I/O error occurs.
-> IndexOutOfBoundsException : if start or end are -ve or start > end or 
                                  end > char_sq.length

Examples of Writer Class in Java

Example 1:

Java

// Java program illustrating the working of Writer class
// methods write(int char), write(String str), close()
// write(String str, int offset, int maxlen), flush()
// write(char[] carray, int offset, int maxlen),
// write(char[] carray)

import java.io.*;

public class NewClass {
    public static void main(String[] args)
        throws IOException
    {
        char[] carray = { 'G', 'E', 'E', 'K', 'S' };

        // Initializing Writer
        Writer geek_writer1 = new PrintWriter(System.out);
        Writer geek_writer2 = new PrintWriter(System.out);
        Writer geek_writer3 = new PrintWriter(System.out);
        Writer geek_writer4 = new PrintWriter(System.out);
        Writer geek_writer5 = new PrintWriter(System.out);

        // Use of write(int char) : to write a character
        geek_writer1.write(71);
        geek_writer1.write(70);
        geek_writer1.write(71);

        // Use of flush() method
        System.out.print("Using write(int char[]) : ");
        geek_writer1.flush();

        String str = "Hello Geeks";
        // Use of write(String str) : to write string
        geek_writer2.write(str);

        // Value written by write(String str)
        System.out.print("\nUsing write(String str) : ");
        geek_writer2.flush();

        // Use of write(String str, int offset, int maxlen)
        //: to write part of string
        geek_writer3.write(str, 2, 4);
        geek_writer3.write(str, 5, 6);

        // Value written by write(String str, int offset,
        // int maxlen)
        System.out.print(
            "\nUsing write(str, offset, maxlen) : ");
        geek_writer3.flush();

        geek_writer4.write(carray);
        System.out.print("\nUsing write(char[] carray) : ");
        geek_writer4.flush();

        // Use of write(char[] carray, int offset, int
        // maxlen): to write part of char array
        geek_writer5.write(carray, 1, 3);

        // Value written by write(String str, int offset,
        // int maxlen)
        System.out.print(
            "\nUsing write(carray, offset, maxlen) : ");
        geek_writer5.flush();

        // Use of close() method
        geek_writer1.close();
        geek_writer2.close();
        geek_writer3.close();
        geek_writer4.close();
        geek_writer5.close();
    }
}

Output

Using write(int char[]) : GFG
Using write(String str) : Hello Geeks
Using write(str, offset, maxlen) : llo  Geeks
Using write(char[] carray) : GEEKS
Using write(carray, offset, maxlen) : EEK

Example 2:

Java

// Java program illustrating the working of Writer class
// methods append(CharSequence char_sq), append(char Sw)
// append(CharSequence char_sq, int start,int end)
// flush()

import java.io.*;

public class NewClass {
    public static void main(String[] args)
        throws IOException
    {
        // Initializing String Writer
        Writer geek_writer1 = new PrintWriter(System.out);
        Writer geek_writer2 = new PrintWriter(System.out);
        Writer geek_writer3 = new PrintWriter(System.out);

        // Use of write(int char) : to write a character
        geek_writer1.append('G');
        geek_writer1.append('G');
        geek_writer1.append('G');
        geek_writer1.append('G');
        geek_writer1.append('G');

        // Use of append(char Sw)
        System.out.print("append(char Sw) : ");
        geek_writer1.flush();

        // Initializing Character Sequence
        CharSequence char_sq1 = "1 Hello 1";
        CharSequence char_sq2 = " : 2 Geeks 2";

        // Use of append(CharSequence char_sq)
        geek_writer2.append(char_sq1);
        geek_writer2.append(char_sq2);

        System.out.print("\nappend(char_sq) : ");
        geek_writer2.flush();

        // Use of append(CharSequence char_sq,int start,int
        // end)
        geek_writer3.append(char_sq1, 0, 3);
        geek_writer3.append(char_sq2, 3, 6);

        System.out.print("\nappend(char_sq,start,end) : ");
        geek_writer3.flush();
    }
}

Output

append(char Sw) : GGGGG
append(char_sq) : 1 Hello 1 : 2 Geeks 2
append(char_sq,start,end) : 1 H2 G

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