[Chapter 11] StringWriter

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| Chapter 11 The java.io Package |

# StringWriter

## Name

StringWriter

## Synopsis

Class Name:

  `java.io.StringWriter`

Superclass:

  `java.io.Writer`

Immediate Subclasses:

  None

Interfaces Implemented:

  None

Availability:

  New as of JDK 1.1

## Description

The `StringWriter` class represents a stream whose data is written to a string. This class is similar to the `CharArrayWriter` class, which writes its data to a `char` array. The `StringWriter` class uses a `StringBuffer` to store its data; a `String` can be retrieved with the `toString()` method.

## Class Summary

    public class java.io.StringWriter extends java.io.Writer {
      // Constructors
      public StringWriter();
      protected StringWriter(int initialSize);
      // Instance Methods
      public void close();
      public void flush();
      public StringBuffer getBuffer();
      public String toString();
      public void write(int c);
      public void write(char[] cbuf, int off, int len);
      public void write(String str);
      public void write(String str, int off, int len);
    }

## Constructors

### StringWriter

#### public StringWriter()

Description

  This constructor creates a `StringWriter` with an internal buffer that has a default size of 16 characters. The buffer grows automatically as data is written to the stream.

#### protected StringWriter (int initialSize)

Parameters

  `initialSize`

    The initial buffer size.

Description

  This constructor creates a `StringWriter` with an internal buffer that has a size of `initialSize` characters. The buffer grows automatically as data is written to the stream.

## Instance Methods

### close

#### public void close()

Overrides

  `Writer.close()`

Description

  This method does nothing. For most subclassesof `Writer`, this method releases any system resources that are associated with the `Writer` object. However, the `StringWriter`'s internal buffer may be needed for subsequent calls to `toString()`. For this reason, `close()` does nothing, and the internal buffer is not released until the `StringWriter` is garbage collected.

### flush

#### public void flush()

Overrides

  `Writer.flush()`

Description

  This method does nothing. The `StringWriter` writes data directly into its internal buffer; thus it is never necessary to flush the stream.

### getBuffer

#### public StringBuffer getBuffer()

Returns

  A reference to the internal data buffer.

Description

  This method returns a reference to the `StringBuffer` object that is used in this `StringWriter`.

### toString

#### public String toString()

Returns

  A `String` constructed from the internal data buffer.

Overrides

  `Object.toString()`

Description

  This method returns a reference to a `String` object created from the characters stored in this object's internal buffer.

### write

#### public void write(int c)

Parameters

  `c`

    The value to write.

Overrides

  `Writer.write(int)`

Description

  This method writes the given value into the internal buffer. If the buffer is full, it is expanded.

#### public void write(char[] cbuf, int off, int len)

Parameters

  `cbuf`

    An array of characters to write to the stream.

  `off`

    An offset into the character array.

  `len`

    The number of characters to write.

Overrides

  `Writer.write(char[], int, int)`

Description

  This method copies `len` characters to this object's internal buffer from `cbuf`, starting `off` elements from the beginning of the array. If the internal buffer is full, it is expanded.

#### public void write(String str)

Parameters

  `str`

    A `String` to write to the stream.

Overrides

  `Writer.write(String)`

Description

  This method copies the characters of `str` into this object's internal buffer. If the internal buffer is full, it is expanded.

#### public void write(String str, int off, int len)

Parameters

  `str`

    A `String` to write to the stream.

  `off`

    An offset into the string.

  `len`

    The number of characters to write.

Overrides

  `Writer.write(String, int, int)`

Description

  This method copies `len` characters to this object's internal buffer from `str`, starting `off` characters from the beginning of the given string. If the internal buffer is full, it is expanded.

## Inherited Methods

Method | Inherited From | Method | Inherited From
--- | --- | --- | ---
`clone()` | `Object` | `equals(Object)` | `Object`
`finalize()` | `Object` | `getClass()` | `Object`
`hashCode()` | `Object` | `notify()` | `Object`
`notifyAll()` | `Object` | `wait()` | `Object`
`wait(long)` | `Object` | `wait(long, int)` | `Object`
`write(char[])` | `Writer` |  |

## See Also

`CharArrayWriter`, `String`, `StringBuffer`, `Writer`

StringReader |  | SyncFailedException