Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Methods](https://developer.android.com/reference/java/io/DataOutput#pubmethods)
# DataOutput
` public interface DataOutput `
` `
|---|
| java.io.DataOutput |
Known indirect subclasses [DataOutputStream](https://developer.android.com/reference/java/io/DataOutputStream), [ObjectOutput](https://developer.android.com/reference/java/io/ObjectOutput), [ObjectOutputStream](https://developer.android.com/reference/java/io/ObjectOutputStream), [RandomAccessFile](https://developer.android.com/reference/java/io/RandomAccessFile) [DataOutputStream](https://developer.android.com/reference/java/io/DataOutputStream) A data output stream lets an application write primitive Java data types to an output stream in a portable way. [ObjectOutput](https://developer.android.com/reference/java/io/ObjectOutput) ObjectOutput extends the DataOutput interface to include writing of objects. [ObjectOutputStream](https://developer.android.com/reference/java/io/ObjectOutputStream) An ObjectOutputStream writes primitive data types and graphs of Java objects to an OutputStream. [RandomAccessFile](https://developer.android.com/reference/java/io/RandomAccessFile) Instances of this class support both reading and writing to a random access file.
*** ** * ** ***
The `DataOutput` interface provides for converting data from any of the Java primitive types to a series of bytes and writing these bytes to a binary stream. There is also a facility for converting a `String` into [modified UTF-8](https://developer.android.com/reference/java/io/DataInput#modified-utf-8) format and writing the resulting series of bytes.
For all the methods in this interface that write bytes, it is generally true that if a byte cannot be written for any reason, an `IOException` is thrown.
**See also:**
- `https://developer.android.com/reference/java/io/DataInput`
- `https://developer.android.com/reference/java/io/DataOutputStream`
## Summary
| ### Public methods ||
|---|---|
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#write(byte[])(byte[] b) ` Writes to the output stream all the bytes in array `b`. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#write(byte[],%20int,%20int)(byte[] b, int off, int len) ` Writes `len` bytes from array `b`, in order, to the output stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#write(int)(int b) ` Writes to the output stream the eight low-order bits of the argument `b`. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeBoolean(boolean)(boolean v) ` Writes a `boolean` value to this output stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeByte(int)(int v) ` Writes to the output stream the eight low- order bits of the argument `v`. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeBytes(java.lang.String)(https://developer.android.com/reference/java/lang/String s) ` Writes a string to the output stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeChar(int)(int v) ` Writes a `char` value, which is comprised of two bytes, to the output stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeChars(java.lang.String)(https://developer.android.com/reference/java/lang/String s) ` Writes every character in the string `s`, to the output stream, in order, two bytes per character. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeDouble(double)(double v) ` Writes a `double` value, which is comprised of eight bytes, to the output stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeFloat(float)(float v) ` Writes a `float` value, which is comprised of four bytes, to the output stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeInt(int)(int v) ` Writes an `int` value, which is comprised of four bytes, to the output stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeLong(long)(long v) ` Writes a `long` value, which is comprised of eight bytes, to the output stream. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeShort(int)(int v) ` Writes two bytes to the output stream to represent the value of the argument. |
| ` abstract void` | ` https://developer.android.com/reference/java/io/DataOutput#writeUTF(java.lang.String)(https://developer.android.com/reference/java/lang/String s) ` Writes two bytes of length information to the output stream, followed by the [modified UTF-8](https://developer.android.com/reference/java/io/DataInput#modified-utf-8) representation of every character in the string `s`. |
## Public methods
### write
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void write (byte[] b)
```
Writes to the output stream all the bytes in array `b`. If `b` is `null`, a `NullPointerException` is thrown. If `b.length` is zero, then no bytes are written. Otherwise, the byte `b[0]` is written first, then `b[1]`, and so on; the last byte written is `b[b.length-1]`.
| Parameters ||
|---|---|
| `b` | `byte`: the data.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### write
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void write (byte[] b,
int off,
int len)
```
Writes `len` bytes from array `b`, in order, to the output stream. If `b` is `null`, a `NullPointerException` is thrown. If `off` is negative, or `len` is negative, or `off+len` is greater than the length of the array `b`, then an `IndexOutOfBoundsException` is thrown. If `len` is zero, then no bytes are written. Otherwise, the byte `b[off]` is written first, then `b[off+1]`, and so on; the last byte written is `b[off+len-1]`.
| Parameters ||
|---|---|
| `b` | `byte`: the data.
|
| `off` | `int`: the start offset in the data.
|
| `len` | `int`: the number of bytes to write.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### write
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void write (int b)
```
Writes to the output stream the eight low-order bits of the argument `b`. The 24 high-order bits of `b` are ignored.
| Parameters ||
|---|---|
| `b` | `int`: the byte to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeBoolean
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeBoolean (boolean v)
```
Writes a `boolean` value to this output stream. If the argument `v` is `true`, the value `(byte)1` is written; if `v` is `false`, the value `(byte)0` is written. The byte written by this method may be read by the `readBoolean` method of interface `DataInput`, which will then return a `boolean` equal to `v`.
| Parameters ||
|---|---|
| `v` | `boolean`: the boolean to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeByte
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeByte (int v)
```
Writes to the output stream the eight low- order bits of the argument `v`. The 24 high-order bits of `v` are ignored. (This means that `writeByte` does exactly the same thing as `write` for an integer argument.) The byte written by this method may be read by the `readByte` method of interface `DataInput`, which will then return a `byte` equal to `(byte)v`.
| Parameters ||
|---|---|
| `v` | `int`: the byte value to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeBytes
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeBytes (String s)
```
Writes a string to the output stream. For every character in the string `s`, taken in order, one byte is written to the output stream. If `s` is `null`, a `NullPointerException` is thrown.
If `s.length` is zero, then no bytes are written. Otherwise, the character `s[0]` is written first, then `s[1]`, and so on; the last character written is `s[s.length-1]`. For each character, one byte is written, the low-order byte, in exactly the manner of the `writeByte` method . The high-order eight bits of each character in the string are ignored.
| Parameters ||
|---|---|
| `s` | `String`: the string of bytes to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeChar
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeChar (int v)
```
Writes a `char` value, which is comprised of two bytes, to the output stream. The byte values to be written, in the order shown, are:
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be read by the `readChar` method of interface `DataInput` , which will then return a `char` equal to `(char)v`.
| Parameters ||
|---|---|
| `v` | `int`: the `char` value to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeChars
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeChars (String s)
```
Writes every character in the string `s`, to the output stream, in order, two bytes per character. If `s` is `null`, a `NullPointerException` is thrown. If `s.length` is zero, then no characters are written. Otherwise, the character `s[0]` is written first, then `s[1]`, and so on; the last character written is `s[s.length-1]`. For each character, two bytes are actually written, high-order byte first, in exactly the manner of the `writeChar` method.
| Parameters ||
|---|---|
| `s` | `String`: the string value to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeDouble
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeDouble (double v)
```
Writes a `double` value, which is comprised of eight bytes, to the output stream. It does this as if it first converts this `double` value to a `long` in exactly the manner of the `Double.doubleToLongBits` method and then writes the `long` value in exactly the manner of the `writeLong` method. The bytes written by this method may be read by the `readDouble` method of interface `DataInput`, which will then return a `double` equal to `v`.
| Parameters ||
|---|---|
| `v` | `double`: the `double` value to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeFloat
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeFloat (float v)
```
Writes a `float` value, which is comprised of four bytes, to the output stream. It does this as if it first converts this `float` value to an `int` in exactly the manner of the `Float.floatToIntBits` method and then writes the `int` value in exactly the manner of the `writeInt` method. The bytes written by this method may be read by the `readFloat` method of interface `DataInput`, which will then return a `float` equal to `v`.
| Parameters ||
|---|---|
| `v` | `float`: the `float` value to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeInt
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeInt (int v)
```
Writes an `int` value, which is comprised of four bytes, to the output stream. The byte values to be written, in the order shown, are:
(byte)(0xff & (v >> 24))
(byte)(0xff & (v >> 16))
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be read by the `readInt` method of interface `DataInput` , which will then return an `int` equal to `v`.
| Parameters ||
|---|---|
| `v` | `int`: the `int` value to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeLong
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeLong (long v)
```
Writes a `long` value, which is comprised of eight bytes, to the output stream. The byte values to be written, in the order shown, are:
(byte)(0xff & (v >> 56))
(byte)(0xff & (v >> 48))
(byte)(0xff & (v >> 40))
(byte)(0xff & (v >> 32))
(byte)(0xff & (v >> 24))
(byte)(0xff & (v >> 16))
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be read by the `readLong` method of interface `DataInput` , which will then return a `long` equal to `v`.
| Parameters ||
|---|---|
| `v` | `long`: the `long` value to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeShort
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeShort (int v)
```
Writes two bytes to the output stream to represent the value of the argument. The byte values to be written, in the order shown, are:
(byte)(0xff & (v >> 8))
(byte)(0xff & v)
The bytes written by this method may be read by the `readShort` method of interface `DataInput` , which will then return a `short` equal to `(short)v`.
| Parameters ||
|---|---|
| `v` | `int`: the `short` value to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |
### writeUTF
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public abstract void writeUTF (String s)
```
Writes two bytes of length information to the output stream, followed by the [modified UTF-8](https://developer.android.com/reference/java/io/DataInput#modified-utf-8) representation of every character in the string `s`. If `s` is `null`, a `NullPointerException` is thrown. Each character in the string `s` is converted to a group of one, two, or three bytes, depending on the value of the character.
If a character `c` is in the range `\u0001` through `\u007f`, it is represented by one byte:
```
(byte)c
```
If a character `c` is `\u0000` or is in the range `\u0080` through `\u07ff`, then it is represented by two bytes, to be written in the order shown:
(byte)(0xc0 | (0x1f & (c >> 6)))
(byte)(0x80 | (0x3f & c))
If a character `c` is in the range `\u0800` through `uffff`, then it is represented by three bytes, to be written in the order shown:
(byte)(0xe0 | (0x0f & (c >> 12)))
(byte)(0x80 | (0x3f & (c >> 6)))
(byte)(0x80 | (0x3f & c))
First, the total number of bytes needed to represent all the characters of `s` is calculated. If this number is larger than `65535`, then a `UTFDataFormatException` is thrown. Otherwise, this length is written to the output stream in exactly the manner of the `writeShort` method; after this, the one-, two-, or three-byte representation of each character in the string `s` is written.
The bytes written by this method may be read by the `readUTF` method of interface `DataInput` , which will then return a `String` equal to `s`.
| Parameters ||
|---|---|
| `s` | `String`: the string value to be written.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | if an I/O error occurs. |