Added in API level 1

PushbackInputStream

open class PushbackInputStream : FilterInputStream
kotlin.Any
   ↳ java.io.InputStream
   ↳ java.io.FilterInputStream
   ↳ java.io.PushbackInputStream

A PushbackInputStream adds functionality to another input stream, namely the ability to "push back" or "unread" bytes, by storing pushed-back bytes in an internal buffer. This is useful in situations where it is convenient for a fragment of code to read an indefinite number of data bytes that are delimited by a particular byte value; after reading the terminating byte, the code fragment can "unread" it, so that the next read operation on the input stream will reread the byte that was pushed back. For example, bytes representing the characters constituting an identifier might be terminated by a byte representing an operator character; a method whose job is to read just an identifier can read until it sees the operator and then push the operator back to be re-read.

Summary

Public constructors

Creates a PushbackInputStream with a pushback buffer of the specified size, and saves its argument, the input stream in, for later use.

Creates a PushbackInputStream with a 1-byte pushback buffer, and saves its argument, the input stream in, for later use.

Public methods
open Int

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.

open Unit

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

open Unit
mark(readlimit: Int)

Marks the current position in this input stream.

open Boolean

Tests if this input stream supports the mark and reset methods, which it does not.

open Int

Reads the next byte of data from this input stream.

open Int
read(b: ByteArray!, off: Int, len: Int)

Reads up to len bytes of data from this input stream into an array of bytes.

open Unit

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

open Long
skip(n: Long)

Skips over and discards n bytes of data from this input stream.

open Unit
unread(b: Int)

Pushes back a byte by copying it to the front of the pushback buffer.

open Unit
unread(b: ByteArray!, off: Int, len: Int)

Pushes back a portion of an array of bytes by copying it to the front of the pushback buffer.

open Unit

Pushes back an array of bytes by copying it to the front of the pushback buffer.

Inherited functions
Properties
ByteArray!

The pushback buffer.

Int

The position within the pushback buffer from which the next byte will be read.

Inherited properties

Public constructors

PushbackInputStream

Added in API level 1
PushbackInputStream(
    in: InputStream!,
    size: Int)

Creates a PushbackInputStream with a pushback buffer of the specified size, and saves its argument, the input stream in, for later use. Initially, the pushback buffer is empty.

Parameters
in InputStream!: the input stream from which bytes will be read.
size Int: the size of the pushback buffer.
Exceptions
java.lang.IllegalArgumentException if size <= 0

PushbackInputStream

Added in API level 1
PushbackInputStream(in: InputStream!)

Creates a PushbackInputStream with a 1-byte pushback buffer, and saves its argument, the input stream in, for later use. Initially, the pushback buffer is empty.

Parameters
in InputStream!: the input stream from which bytes will be read.

Public methods

available

Added in API level 1
open fun available(): Int

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.

The method returns the sum of the number of bytes that have been pushed back and the value returned by available.

Return
Int the number of bytes that can be read (or skipped over) from the input stream without blocking.
Exceptions
java.io.IOException if an I/O error occurs.
java.io.IOException if this input stream has been closed by invoking its #close() method, or an I/O error occurs.

close

Added in API level 1
open fun close(): Unit

Closes this input stream and releases any system resources associated with the stream. Once the stream has been closed, further read(), unread(), available(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.

Exceptions
java.lang.Exception if this resource cannot be closed
java.io.IOException if an I/O error occurs.
java.io.IOException if an I/O error occurs.

mark

Added in API level 1
open fun mark(readlimit: Int): Unit

Marks the current position in this input stream.

The mark method of PushbackInputStream does nothing.

Parameters
readlimit Int: the maximum limit of bytes that can be read before the mark position becomes invalid.

markSupported

Added in API level 1
open fun markSupported(): Boolean

Tests if this input stream supports the mark and reset methods, which it does not.

Return
Boolean false, since this class does not support the mark and reset methods.

read

Added in API level 1
open fun read(): Int

Reads the next byte of data from this 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.

This method returns the most recently pushed-back byte, if there is one, and otherwise calls the read method of its underlying input stream and returns whatever value that method returns.

Return
Int the next byte of data, or -1 if the end of the stream has been reached.
Exceptions
java.io.IOException if an I/O error occurs.
java.io.IOException if this input stream has been closed by invoking its #close() method, or an I/O error occurs.

read

Added in API level 1
open fun read(
    b: ByteArray!,
    off: Int,
    len: Int
): Int

Reads up to len bytes of data from this input stream into an array of bytes. This method first reads any pushed-back bytes; after that, if fewer than len bytes have been read then it reads from the underlying input stream. If len is not zero, the method blocks until at least 1 byte of input is available; otherwise, no bytes are read and 0 is returned.

Parameters
b ByteArray!: the buffer into which the data is read.
off Int: the start offset in the destination array b
len Int: the maximum number of bytes read.
Return
Int 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.
Exceptions
java.io.IOException 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.
java.lang.NullPointerException If b is null.
java.lang.IndexOutOfBoundsException If off is negative, len is negative, or len is greater than b.length - off
java.lang.NullPointerException If b is null.
java.lang.IndexOutOfBoundsException If off is negative, len is negative, or len is greater than b.length - off
java.io.IOException if this input stream has been closed by invoking its #close() method, or an I/O error occurs.

reset

Added in API level 1
open fun reset(): Unit

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

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

Exceptions
java.io.IOException if this stream has not been marked or if the mark has been invalidated.
java.io.IOException if this method is invoked.

skip

Added in API level 1
open fun skip(n: Long): Long

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 zero. If n is negative, no bytes are skipped.

The skip method of PushbackInputStream first skips over the bytes in the pushback buffer, if any. It then calls the skip method of the underlying input stream if more bytes need to be skipped. The actual number of bytes skipped is returned.

Parameters
n Long: the number of bytes to be skipped.
Return
Long the actual number of bytes skipped.
Exceptions
java.io.IOException if the stream has been closed by invoking its #close() method, in.skip(n) throws an IOException, or an I/O error occurs.

unread

Added in API level 1
open fun unread(b: Int): Unit

Pushes back a byte by copying it to the front of the pushback buffer. After this method returns, the next byte to be read will have the value (byte)b.

Parameters
b Int: the int value whose low-order byte is to be pushed back.
Exceptions
java.io.IOException If there is not enough room in the pushback buffer for the byte, or this input stream has been closed by invoking its #close() method.

unread

Added in API level 1
open fun unread(
    b: ByteArray!,
    off: Int,
    len: Int
): Unit

Pushes back a portion of an array of bytes by copying it to the front of the pushback buffer. After this method returns, the next byte to be read will have the value b[off], the byte after that will have the value b[off+1], and so forth.

Parameters
b ByteArray!: the byte array to push back.
off Int: the start offset of the data.
len Int: the number of bytes to push back.
Exceptions
java.io.IOException If there is not enough room in the pushback buffer for the specified number of bytes, or this input stream has been closed by invoking its #close() method.

unread

Added in API level 1
open fun unread(b: ByteArray!): Unit

Pushes back an array of bytes by copying it to the front of the pushback buffer. After this method returns, the next byte to be read will have the value b[0], the byte after that will have the value b[1], and so forth.

Parameters
b ByteArray!: the byte array to push back
Exceptions
java.io.IOException If there is not enough room in the pushback buffer for the specified number of bytes, or this input stream has been closed by invoking its #close() method.

Properties

buf

Added in API level 1
protected var buf: ByteArray!

The pushback buffer.

pos

Added in API level 1
protected var pos: Int

The position within the pushback buffer from which the next byte will be read. When the buffer is empty, pos is equal to buf.length; when the buffer is full, pos is equal to zero.