# InputStream

public abstract class **InputStream** extends [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)  
implements [Closeable](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Closeable.html)

|---|---|---|
| Known Direct Subclasses [ByteArrayInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/ByteArrayInputStream.html), [FileInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FileInputStream.html), [FilterInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FilterInputStream.html), [ObjectInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/ObjectInputStream.html), [PipedInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PipedInputStream.html), [SequenceInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/SequenceInputStream.html), [StringBufferInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/StringBufferInputStream.html) |---|---| | [ByteArrayInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/ByteArrayInputStream.html) | A `ByteArrayInputStream` contains an internal buffer that contains bytes that may be read from the stream. | | [FileInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FileInputStream.html) | A `FileInputStream` obtains input bytes from a file in a file system. | | [FilterInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FilterInputStream.html) | A `FilterInputStream` contains some other input stream, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality. | | [ObjectInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/ObjectInputStream.html) | An ObjectInputStream deserializes primitive data and objects previously written using an ObjectOutputStream. | | [PipedInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PipedInputStream.html) | Receives information from a communications pipe. | | [SequenceInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/SequenceInputStream.html) | A `SequenceInputStream` represents the logical concatenation of other input streams. | | [StringBufferInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/StringBufferInputStream.html) | *This class is deprecated. This class does not properly convert characters into bytes. As of JDK 1.1, the preferred way to create a stream from a string is via the `StringReader` class.* | |||

|---|---|---|
| Known Indirect Subclasses [BufferedInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/BufferedInputStream.html), [CheckedInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/CheckedInputStream.html), [CipherInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/javax/crypto/CipherInputStream.html), [DataInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/DataInputStream.html), [DeflaterInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/DeflaterInputStream.html), [DigestInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/security/DigestInputStream.html), [GZIPInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/GZIPInputStream.html), [InflaterInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/InflaterInputStream.html), [JarInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/jar/JarInputStream.html), [LineNumberInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/LineNumberInputStream.html), [PushbackInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PushbackInputStream.html), [ZipInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/ZipInputStream.html) |---|---| | [BufferedInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/BufferedInputStream.html) | A `BufferedInputStream` adds functionality to another input stream-namely, the ability to buffer the input and to support the `mark` and `reset` methods. | | [CheckedInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/CheckedInputStream.html) | An input stream that also maintains a checksum of the data being read. | | [CipherInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/javax/crypto/CipherInputStream.html) | A CipherInputStream is composed of an InputStream and a Cipher so that read() methods return data that are read in from the underlying InputStream but have been additionally processed by the Cipher. | | [DataInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/DataInputStream.html) | A data input stream lets an application read primitive Java data types from an underlying input stream in a machine-independent way. | | [DeflaterInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/DeflaterInputStream.html) | Implements an input stream filter for compressing data in the "deflate" compression format. | | [DigestInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/security/DigestInputStream.html) | A transparent stream that updates the associated message digest using the bits going through the stream. | | [GZIPInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/GZIPInputStream.html) | This class implements a stream filter for reading compressed data in the GZIP file format. | | [InflaterInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/InflaterInputStream.html) | This class implements a stream filter for uncompressing data in the "deflate" compression format. | | [JarInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/jar/JarInputStream.html) | The `JarInputStream` class is used to read the contents of a JAR file from any input stream. | | [LineNumberInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/LineNumberInputStream.html) | *This class is deprecated. This class incorrectly assumes that bytes adequately represent characters. As of JDK 1.1, the preferred way to operate on character streams is via the new character-stream classes, which include a class for counting line numbers.* | | [PushbackInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PushbackInputStream.html) | A `PushbackInputStream` adds functionality to another input stream, namely the ability to "push back" or "unread" one byte. | | [ZipInputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/zip/ZipInputStream.html) | This class implements an input stream filter for reading files in the ZIP file format. | |||

This abstract class is the superclass of all classes representing
an input stream of bytes.

Applications that need to define a subclass of `InputStream`
must always provide a method that returns the next byte of input.

##### See Also

- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/BufferedInputStream.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/ByteArrayInputStream.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/DataInputStream.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/FilterInputStream.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#read()`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/OutputStream.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/PushbackInputStream.html`

### Public Constructor Summary

|---|---|
|   | [InputStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#InputStream())() |

### Public Method Summary

|---|---|
| int | [available](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#available())() Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream. |
| void | [close](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#close())() Closes this input stream and releases any system resources associated with the stream. |
| synchronized void | [mark](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#mark(int))(int readlimit) Marks the current position in this input stream. |
| boolean | [markSupported](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#markSupported())() Tests if this input stream supports the `mark` and `reset` methods. |
| abstract int | [read](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#read())() Reads the next byte of data from the input stream. |
| int | [read](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#read(byte[],%20int,%20int))(byte\[\] b, int off, int len) Reads up to `len` bytes of data from the input stream into an array of bytes. |
| int | [read](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#read(byte[]))(byte\[\] b) Reads some number of bytes from the input stream and stores them into the buffer array `b`. |
| synchronized void | [reset](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#reset())() Repositions this stream to the position at the time the `mark` method was last called on this input stream. |
| long | [skip](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#skip(long))(long n) Skips over and discards `n` bytes of data from this input stream. |

### Inherited Method Summary

From class [java.lang.Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)

|---|---|
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#clone())() Creates and returns a copy of this `Object`. |
| boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj) Compares this instance with the specified object and indicates if they are equal. |
| void | [finalize](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#finalize())() Invoked when the garbage collector has detected that this instance is no longer reachable. |
| final [Class](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html)\<?\> | [getClass](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#getClass())() Returns the unique instance of `https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html` that represents this object's class. |
| int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#hashCode())() Returns an integer hash code for this object. |
| final void | [notify](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notify())() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| final void | [notifyAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notifyAll())() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [toString](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#toString())() Returns a string containing a concise, human-readable description of this object. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long,%20int))(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long))(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait())() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object. |

From interface [java.io.Closeable](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Closeable.html)

|---|---|
| abstract void | [close](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Closeable.html#close())() Closes this stream and releases any system resources associated with it. |

From interface [java.lang.AutoCloseable](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/AutoCloseable.html)

|---|---|
| abstract void | [close](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/AutoCloseable.html#close())() Closes this resource, relinquishing any underlying resources. |

## Public Constructors

#### public
**InputStream**
()

<br />

## Public Methods

#### public int
**available**
()

Returns an estimate of the number of bytes that can be read (or
skipped over) from this input stream without blocking by the next
invocation of a method for this input stream. The next invocation
might be the same thread or another thread. A single read or skip of this
many bytes will not block, but may read or skip fewer bytes.

Note that while some implementations of `InputStream` will return
the total number of bytes in the stream, many will not. It is
never correct to use the return value of this method to allocate
a buffer intended to hold all data in this stream.

A subclass' implementation of this method may choose to throw an
`https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html` if this input stream has been closed by
invoking the `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#close()` method.

The `available` method for class `InputStream` always
returns `0`.

This method should be overridden by subclasses.

##### Returns

- an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking or `0` when it reaches the end of the input stream.

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if an I/O error occurs. |
|---|---|

#### public void
**close**
()

Closes this input stream and releases any system resources associated
with the stream.

The `close` method of `InputStream` does
nothing.

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if an I/O error occurs. |
|---|---|

#### public synchronized void
**mark**
(int readlimit)

Marks the current position in this input stream. A subsequent call to
the `reset` method repositions this stream at the last marked
position so that subsequent reads re-read the same bytes.

The `readlimit` arguments tells this input stream to
allow that many bytes to be read before the mark position gets
invalidated.

The general contract of `mark` is that, if the method
`markSupported` returns `true`, the stream somehow
remembers all the bytes read after the call to `mark` and
stands ready to supply those same bytes again if and whenever the method
`reset` is called. However, the stream is not required to
remember any data at all if more than `readlimit` bytes are
read from the stream before `reset` is called.

Marking a closed stream should not have any effect on the stream.

The `mark` method of `InputStream` does
nothing.

##### Parameters

| readlimit | the maximum limit of bytes that can be read before the mark position becomes invalid. |
|---|---|

##### See Also

- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#reset()`

#### public boolean
**markSupported**
()

Tests if this input stream supports the `mark` and
`reset` methods. Whether or not `mark` and
`reset` are supported is an invariant property of a
particular input stream instance. The `markSupported` method
of `InputStream` returns `false`.

##### Returns

- `true` if this stream instance supports the mark and reset methods; `false` otherwise.

##### See Also

- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#mark(int)`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#reset()`

#### public abstract int
**read**
()

Reads the next byte of data from the input stream. The value byte is
returned as an `int` in the range `0` to
`255`. If no byte is available because the end of the stream
has been reached, the value `-1` is returned. This method
blocks until input data is available, the end of the stream is detected,
or an exception is thrown.

A subclass must provide an implementation of this method.

##### Returns

- the next byte of data, or `-1` if the end of the stream is reached.

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if an I/O error occurs. |
|---|---|

#### public int
**read**
(byte\[\] b, int off, int len)

Reads up to `len` bytes of data from the input stream into
an array of bytes. An attempt is made to read as many as
`len` bytes, but a smaller number may be read.
The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is
detected, or an exception is thrown.

If `len` is zero, then no bytes are read and
`0` is returned; otherwise, there is an attempt to read at
least one byte. If no byte is available because the stream is at end of
file, the value `-1` is returned; otherwise, at least one
byte is read and stored into `b`.

The first byte read is stored into element `b[off]`, the
next one into `b[off+1]`, and so on. The number of bytes read
is, at most, equal to `len`. Let *k* be the number of
bytes actually read; these bytes will be stored in elements
`b[off]` through `b[off+`*k*`-1]`,
leaving elements `b[off+`*k*`]` through
`b[off+len-1]` unaffected.

In every case, elements `b[0]` through
`b[off]` and elements `b[off+len]` through
`b[b.length-1]` are unaffected.

The `read(b,` `off,` `len)` method
for class `InputStream` simply calls the method
`read()` repeatedly. If the first such call results in an
`IOException`, that exception is returned from the call to
the `read(b,` `off,` `len)` method. If
any subsequent call to `read()` results in a
`IOException`, the exception is caught and treated as if it
were end of file; the bytes read up to that point are stored into
`b` and the number of bytes read before the exception
occurred is returned. The default implementation of this method blocks
until the requested amount of input data `len` has been read,
end of file is detected, or an exception is thrown. Subclasses are encouraged
to provide a more efficient implementation of this method.

##### Parameters

| b | the buffer into which the data is read. |
| off | the start offset in array `b` at which the data is written. |
| len | the maximum number of bytes to read. |
|---|---|

##### Returns

- the total number of bytes read into the buffer, or `-1` if there is no more data because the end of the stream has been reached.

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs. |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | If `b` is `null`. |
| [IndexOutOfBoundsException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IndexOutOfBoundsException.html) | If `off` is negative, `len` is negative, or `len` is greater than `b.length - off` |
|---|---|

##### See Also

- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#read()`

#### public int
**read**
(byte\[\] b)

Reads some number of bytes from the input stream and stores them into
the buffer array `b`. The number of bytes actually read is
returned as an integer. This method blocks until input data is
available, end of file is detected, or an exception is thrown.

If the length of `b` is zero, then no bytes are read and
`0` is returned; otherwise, there is an attempt to read at
least one byte. If no byte is available because the stream is at the
end of the file, the value `-1` is returned; otherwise, at
least one byte is read and stored into `b`.

The first byte read is stored into element `b[0]`, the
next one into `b[1]`, and so on. The number of bytes read is,
at most, equal to the length of `b`. Let *k* be the
number of bytes actually read; these bytes will be stored in elements
`b[0]` through `b[`*k*`-1]`,
leaving elements `b[`*k*`]` through
`b[b.length-1]` unaffected.

The `read(b)` method for class `InputStream`
has the same effect as:

     read(b, 0, b.length) 

<br />

##### Parameters

| b | the buffer into which the data is read. |
|---|---|

##### Returns

- the total number of bytes read into the buffer, or `-1` if there is no more data because the end of the stream has been reached.

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | If the first byte cannot be read for any reason other than the end of the file, if the input stream has been closed, or if some other I/O error occurs. |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `b` is `null`. |
|---|---|

##### See Also

- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#read(byte[],%20int,%20int)`

#### public synchronized void
**reset**
()

Repositions this stream to the position at the time the
`mark` method was last called on this input stream.

The general contract of `reset` is:

- If the method `markSupported` returns `true`, then:
  - If the method `mark` has not been called since the stream was created, or the number of bytes read from the stream since `mark` was last called is larger than the argument to `mark` at that last call, then an `IOException` might be thrown.
  - If such an `IOException` is not thrown, then the stream is reset to a state such that all the bytes read since the most recent call to `mark` (or since the start of the file, if `mark` has not been called) will be resupplied to subsequent callers of the `read` method, followed by any bytes that otherwise would have been the next input data as of the time of the call to `reset`.
- If the method `markSupported` returns `false`, then:
  - The call to `reset` may throw an `IOException`.
  - If an `IOException` is not thrown, then the stream is reset to a fixed state that depends on the particular type of the input stream and how it was created. The bytes that will be supplied to subsequent callers of the `read` method depend on the particular type of the input stream.

The method `reset` for class `InputStream`
does nothing except throw an `IOException`.

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if this stream has not been marked or if the mark has been invalidated. |
|---|---|

##### See Also

- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/InputStream.html#mark(int)`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html`

#### public long
**skip**
(long n)

Skips over and discards `n` bytes of data from this input
stream. The `skip` method may, for a variety of reasons, end
up skipping over some smaller number of bytes, possibly `0`.
This may result from any of a number of conditions; reaching end of file
before `n` bytes have been skipped is only one possibility.
The actual number of bytes skipped is returned. If `n` is
negative, the `skip` method for class `InputStream` always
returns 0, and no bytes are skipped. Subclasses may handle the negative
value differently.

The `skip` method of this class creates a
byte array and then repeatedly reads into it until `n` bytes
have been read or the end of the stream has been reached. Subclasses are
encouraged to provide a more efficient implementation of this method.
For instance, the implementation may depend on the ability to seek.

##### Parameters

| n | the number of bytes to be skipped. |
|---|---|

##### Returns

- the actual number of bytes skipped.

##### Throws

| [IOException](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/IOException.html) | if the stream does not support seek, or if some other I/O error occurs. |
|---|---|