Java.io.StringWriter class in Java

Java StringWriter class creates a string from the characters of the String Buffer stream. Methods of the StringWriter class in Java can also be called after closing the Stream as this will raise no IO Exception. 

Declaration in Java StringWriter Class

public class StringWriter
  extends Writer

Constructors in StringWriter Class in Java

Constructors used in String Writer Class in Java are mentioned below:

• StringWriter() : Creates a new StringWriter using the initial or default size of String Buffer
• StringWriter(int size) : Creates a new StringWriter using the mentioned size of String Buffer

Methods in Java StringWriter Class 

All the methods involved with the Java StringWriter class are mentioned below:

Method	Description
append(char Sw)	appends a single character to the String Buffer.
append(CharSequence char_sq)	appends specified character sequences to the String Buffer.
append(CharSequence ,char_sq,int start,int end)	appends specified part of a character sequence to the String Buffer.
flush()	flushes the StringWriter stream.
getBuffer()	returns the StringBuffer of StringWriter.
write(int char)	writes a single character to the String Buffer.
write(String str)	writes string to the String Buffer.
write(String str, int offset, int maxlen)	writes some part of the string to the String Buffer.
write(char[] carray, int offset, int maxlen)	writes some part of the character array to the String Buffer.
toString()	returns value of the String Buffer as string
close()	closes String Buffer.Since, method can also be called after closing the String Buffer so,it play no role.

1. write(int char)

java.io.StringWriter.write(int char) writes a single character to the String Buffer. 

Syntax: public void write(int char)

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

Return  :
void

2. write(String str)

java.io.StringWriter.write(String str) writes string to the String Buffer. 

Syntax: public void write(String str)

Parameters : 
str : string to be written to the String Buffer.

Return  :
void

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

java.io.StringWriter.write(String str, int offset, int maxlen) writes some part of the string to the String Buffer. 

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

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

Return  :
void

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

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

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

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

Return  :
void

5. toString()

java.io.StringWriter.toString() returns the value of the String Buffer as a string .

Syntax: public String toString()

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

Return  :
string value of the String Buffer

6. close()

java.io.StringWriter.close() closes String Buffer. Since, method can also be called after closing th String Buffer so, it play no role. 

Syntax: public void close()

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

Return  :
void

7. append(char Sw)

java.io.StringWriter.append(char Sw) appends a single character to the String Buffer. 

Syntax: public StringWriter append(char Sw)

Parameters : 
Sw : character to be append

Return  :
StringWriter

8. append(CharSequence char_sq)

java.io.StringWriter.append(CharSequence char_sq) appends specified character sequence to the String Buffer. 

Syntax: public StringWriter append(CharSequence char_sq)

Parameters : 
char_sq : Character sequence to append. 

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

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

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

Syntax: public StringWriter 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

10. flush()

java.io.StringWriter.flush() flushes the StringWriter stream.

Syntax: public void flush()

Parameters : 
-----

Return  :
void

11. getBuffer()

java.io.StringWriter.getBuffer() returns the String Buffer of StringWriter. 

Syntax: public StringBuffer getBuffer()

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

Return  :
String Buffer with its current value.

Example

Java program illustrating the use of StringWriter class methods : 

Java

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

import java.io.*;

public class NewClass {
    public static void main(String[] args)
        throws IOException
    {
        // Initializing String Writer
        StringWriter geek_writer1 = new StringWriter();
        StringWriter geek_writer2 = new StringWriter();
        StringWriter geek_writer3 = new StringWriter();
        StringWriter geek_writer4 = new StringWriter();

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

        // Use of toString() : Value written by write(int
        // char)
        System.out.println("Using write(int char) : "
                           + geek_writer1.toString());

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

        // Value written by write(String str)
        System.out.println("Using write(String str) : "
                           + geek_writer2.toString());

        // 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.println(
            "Using write(str, offset, maxlen) : "
            + geek_writer3.toString());

        try {
            // Use of Close() method : to close the
            // geek_writer4 But no use as String Writer
            // method is still working with it
            geek_writer4.close();
        }

        catch (IOException except) {
            System.out.println("ERROR");
            except.printStackTrace();
            ;
        }

        // Initializing character array
        char[] carray = str.toCharArray();

        // Use of write(char[] carray, int offset, int
        // maxlen): to write part of char array
        geek_writer4.write(carray, 4, 6);

        // Value written by write(String str, int offset,
        // int maxlen)
        System.out.println(
            "Using write(carray, offset, maxlen) : "
            + geek_writer4.toString());
    }
}

Output

Using write(int char) : GFG
Using write(String str) : Hello Geeks
Using write(str, offset, maxlen) : llo  Geeks
Using write(carray, offset, maxlen) : o Geek

Java program illustrating use of StringWriter class methods : append(CharSequence char_sq), append(char Sw), append(CharSequence char_sq, int start,int end), flush(), getgetBuffer()

Java

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

import java.io.*;

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

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

        // Use of toString() : Value written by write(int
        // char)
        System.out.println("Using write(int char) : "
                           + geek_writer1.toString());

        // Using flush() method
        geek_writer1.flush();
        System.out.println("Using flush() : "
                           + geek_writer1.toString());

        // Use of append(char Sw)
        System.out.println("append(char Sw) : "
                           + geek_writer1.append(" 1GFG1"));

        // Use of getBuffer() :
        System.out.println("Using geek_writer1 : "
                           + geek_writer1.getBuffer());

        // 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.println("append(char_sq) : "
                           + geek_writer2.toString());

        // 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.println("append(char_sq,start,end) : "
                           + geek_writer3.toString());
    }
}

Output

Using write(int char) : GFG
Using flush() : GFG
append(char Sw) : GFG 1GFG1
Using geek_writer1 : GFG 1GFG1
append(char_sq) : 1 Hello 1 : 2 Geeks 2
append(char_sq,start,end) : 1 H2 G