#

| Chapter 11 The java.io Package |

# DataOutput

## Name

DataOutput

## Synopsis

Interface Name:

  `java.io.DataOutput`

Super-interface:

  None

Immediate Sub-interfaces:

  `java.io.ObjectOutput`

Implemented By:

  `java.io.DataOutputStream`, `java.io.RandomAccessFile`

Availability:

  JDK 1.0 or later

## Description

The `DataOutput` interface defines methods for writing primitive data types to an output stream in a machine-independent manner. All multibyte quantities are written in a format that stores the most significant byte as the first byte and the least significant byte as the last byte.

## Interface Declaration

    public abstract interface java.io.DataOutput {
      // Methods
      public abstract void write(byte[] b);
      public abstract void write(byte[] b, int off, int len);
      public abstract void write(int b);
      public abstract void writeBoolean(boolean v);
      public abstract void writeByte(int v);
      public abstract void writeBytes(String s);
      public abstract void writeChar(int v);
      public abstract void writeChars(String s);
      public abstract void writeDouble(double v);
      public abstract void writeFloat(float v);
      public abstract void writeInt(int v);
      public abstract void writeLong(long v);
      public abstract void writeShort(int v);
      public abstract void writeUTF(String str);
    }

## Methods

### write

#### public abstract void write(int b) throws IOException

Parameters

  `b`

    The value to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes the low-order 8 bits of the given integer `b`.

#### public abstract void write(byte[] b) throws IOException

Parameters

  `b`

    An array of values to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes all of the 8-bit bytes in the given array.

####

     public abstract void write(byte[] b, int off, int len) throws IOException

Parameters

  `b`

    An array of values to write.

  `off`

    An offset into the array.

  `len`

    The number of bytes to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes `len` bytes from the given array, starting `off` elements from the beginning of the array.

### writeBoolean

#### public abstract void writeBoolean(boolean v) throws IOException

Parameters

  `v`

    The `boolean` value to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  If `v` is `true`, this method writes a byte that contains the value `1`. If `v` is `false`, the method writes a byte that contains the value `0`.

### writeByte

#### public abstract void writeByte(int v) throws IOException

Parameters

  `v`

    The value to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes an 8-bit `byte` using the low-order eight bits of the integer `v`.

### writeBytes

#### public abstract void writeBytes(String s) throws IOException

Parameters

  `s`

    The `String` to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes the characters in the given `String` as a sequence of 8-bit bytes. The high-order bytes of the characters in the string are ignored.

### writeChar

#### public abstract void writeChar(int v) throws IOException

Parameters

  `v`

    The value to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes a 16-bit `char` using the low-order 16 bits of the given integer `v`.

### writeChars

#### public abstract void writeChars(String s) throws IOException

Parameters

  `s`

    The `String` to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes the characters in the given `String` object as a sequence of 16-bit characters.

### writeDouble

#### public abstract void writeDouble(double v) throws IOException

Parameters

  `v`

    The `double` value to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes a 64-bit `double`.

### writeFloat

#### public abstract void writeFloat(float v) throws IOException

Parameters

  `v`

    The value to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes a 32-bit `float`.

### writeInt

#### public abstract void writeInt(int v) throws IOException

Parameters

  `v`

    The `int` value to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes a 32-bit `int`.

### writeLong

#### public abstract void writeLong(long v) throws IOException

Parameters

  `v`

    The `long` value to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes a 64-bit `long`.

### writeShort

#### public abstract void writeShort(int v) throws IOException

Parameters

  `v`

    The `short` value to write.

Throws

  `IOException`

    If any kind of I/O error occurs.

Description

  This method writes a 16-bit `short`.

### writeUTF

#### public abstract void writeUTF(String str) throws IOException

Parameters

  `str`

    The `String` to write.

Throws

  IOException

    If any kind of I/O error occurs.

Description

  This method writes the given `String` using UTF-8 encoding. See Appendix B, The UTF-8 Encoding for information on the UTF-8 encoding.

## See Also

`DataOutputStream`, `IOException`, `ObjectOutput`, `RandomAccessFile`

DataInputStream |  | DataOutputStream