Android APIs
public class

LineNumberInputStream

extends FilterInputStream
java.lang.Object
   ↳ java.io.InputStream
     ↳ java.io.FilterInputStream
       ↳ java.io.LineNumberInputStream

This class was deprecated in API level 1.
Use LineNumberReader instead.

Class Overview

Wraps an existing InputStream and counts the line terminators encountered while reading the data. Line numbering starts at 0. Recognized line terminator sequences are '\r', '\n' and "\r\n". When using read, line terminator sequences are always translated into '\n'.

Summary

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Inherited Fields
From class java.io.FilterInputStream
Public Constructors
LineNumberInputStream(InputStream in)
Constructs a new LineNumberInputStream on the InputStream in.
Public Methods
int available()
Returns an estimated number of bytes that can be read or skipped without blocking for more input.

Note that the source stream may just be a sequence of "\r\n" bytes which are converted into '\n' by this stream.

int getLineNumber()
Returns the current line number for this stream.
void mark(int readlimit)
Sets a mark position in this stream.
int read()
Reads a single byte from the filtered stream and returns it as an integer in the range from 0 to 255.
int read(byte[] buffer, int byteOffset, int byteCount)
Reads up to byteCount bytes from the filtered stream and stores them in the byte array buffer starting at byteOffset.
void reset()
Resets this stream to the last marked location.
void setLineNumber(int lineNumber)
Sets the line number of this stream to the specified lineNumber.
long skip(long byteCount)
Skips count number of bytes in this stream.
[Expand]
Inherited Methods
From class java.io.FilterInputStream
From class java.io.InputStream
From class java.lang.Object
From interface java.io.Closeable
From interface java.lang.AutoCloseable

Public Constructors

public LineNumberInputStream (InputStream in)

Added in API level 1

Constructs a new LineNumberInputStream on the InputStream in. Line numbers are counted for all data read from this stream.

Warning: passing a null source creates an invalid LineNumberInputStream. All operations on such a stream will fail.

Parameters
in The non-null input stream to count line numbers.

Public Methods

public int available ()

Added in API level 1

Returns an estimated number of bytes that can be read or skipped without blocking for more input.

Note that this method provides such a weak guarantee that it is not very useful in practice.

Firstly, the guarantee is "without blocking for more input" rather than "without blocking": a read may still block waiting for I/O to complete — the guarantee is merely that it won't have to wait indefinitely for data to be written. The result of this method should not be used as a license to do I/O on a thread that shouldn't be blocked.

Secondly, the result is a conservative estimate and may be significantly smaller than the actual number of bytes available. In particular, an implementation that always returns 0 would be correct. In general, callers should only use this method if they'd be satisfied with treating the result as a boolean yes or no answer to the question "is there definitely data ready?".

Thirdly, the fact that a given number of bytes is "available" does not guarantee that a read or skip will actually read or skip that many bytes: they may read or skip fewer.

It is particularly important to realize that you must not use this method to size a container and assume that you can read the entirety of the stream without needing to resize the container. Such callers should probably write everything they read to a ByteArrayOutputStream and convert that to a byte array. Alternatively, if you're reading from a file, length() returns the current length of the file (though assuming the file's length can't change may be incorrect, reading a file is inherently racy).

The default implementation of this method in InputStream always returns 0. Subclasses should override this method if they are able to indicate the number of bytes available.

Note that the source stream may just be a sequence of "\r\n" bytes which are converted into '\n' by this stream. Therefore, available returns only in.available() / 2 bytes as result.

Returns
int the estimated number of bytes available
Throws
IOException

public int getLineNumber ()

Added in API level 1

Returns the current line number for this stream. Numbering starts at 0.

Returns
int the current line number.

public void mark (int readlimit)

Added in API level 1

Sets a mark position in this stream. The parameter readlimit indicates how many bytes can be read before the mark is invalidated. Sending reset() will reposition this stream back to the marked position, provided that readlimit has not been surpassed. The line number count will also be reset to the last marked line number count.

This implementation sets a mark in the filtered stream.

Parameters
readlimit the number of bytes that can be read from this stream before the mark is invalidated.

public int read ()

Added in API level 1

Reads a single byte from the filtered stream and returns it as an integer in the range from 0 to 255. Returns -1 if the end of this stream has been reached.

The line number count is incremented if a line terminator is encountered. Recognized line terminator sequences are '\r', '\n' and "\r\n". Line terminator sequences are always translated into '\n'.

Returns
int the byte read or -1 if the end of the filtered stream has been reached.
Throws
IOException if the stream is closed or another IOException occurs.

public int read (byte[] buffer, int byteOffset, int byteCount)

Added in API level 1

Reads up to byteCount bytes from the filtered stream and stores them in the byte array buffer starting at byteOffset. Returns the number of bytes actually read or -1 if no bytes have been read and the end of this stream has been reached.

The line number count is incremented if a line terminator is encountered. Recognized line terminator sequences are '\r', '\n' and "\r\n". Line terminator sequences are always translated into '\n'.

Parameters
buffer
byteOffset
byteCount
Returns
int
Throws
IndexOutOfBoundsException if byteOffset < 0 || byteCount < 0 || byteOffset + byteCount > buffer.length.
IOException if this stream is closed or another IOException occurs.
NullPointerException if buffer == null.

public void reset ()

Added in API level 1

Resets this stream to the last marked location. It also resets the line count to what is was when this stream was marked.

Throws
IOException if this stream is already closed, no mark has been set or the mark is no longer valid because more than readlimit bytes have been read since setting the mark.

public void setLineNumber (int lineNumber)

Added in API level 1

Sets the line number of this stream to the specified lineNumber. Note that this may have side effects on the line number associated with the last marked position.

Parameters
lineNumber the new lineNumber value.

See also:

public long skip (long byteCount)

Added in API level 1

Skips count number of bytes in this stream. Subsequent calls to read will not return these bytes unless reset is used. This implementation skips byteCount bytes in the filtered stream and increments the line number count whenever line terminator sequences are skipped.

Parameters
byteCount the number of bytes to skip.
Returns
long the number of bytes actually skipped.
Throws
IOException if this stream is closed or another IOException occurs.