Module java.base
Package java.io

# Class CharArrayReader

java.lang.Object
java.io.Reader
java.io.CharArrayReader

All Implemented Interfaces:
  `Closeable`, `AutoCloseable`, `Readable`

public class CharArrayReader extends Reader
This class implements a character buffer that can be used as a character-input stream.

Since:
  1.1

## Field Summary

Fields
Modifier and Type
Field
Description
`protected char[]`
`buf`
The character buffer.
`protected int`
`count`
The index of the end of this buffer.
`protected int`
`markedPos`
The position of mark in buffer.
`protected int`
`pos`
The current buffer position.

### Fields declared in class java.io.Reader

`lock`

## Constructor Summary

Constructors
Constructor
Description
`CharArrayReader(char[] buf)`
Creates a CharArrayReader from the specified array of chars.
`CharArrayReader(char[] buf, int offset, int length)`
Creates a CharArrayReader from the specified array of chars.

## Method Summary

Modifier and Type
Method
Description
`void`
`close()`
Closes the stream and releases any system resources associated with it.
`void`
`mark(int readAheadLimit)`
Marks the present position in the stream.
`boolean`
`markSupported()`
Tells whether this stream supports the mark() operation, which it does.
`int`
`read()`
Reads a single character.
`int`
`read(char[] cbuf, int off, int len)`
Reads characters into a portion of an array.
`boolean`
`ready()`
Tells whether this stream is ready to be read.
`void`
`reset()`
Resets the stream to the most recent mark, or to the beginning if it has never been marked.
`long`
`skip(long n)`
Skips characters.

### Methods declared in class java.io.Reader

`nullReader, read, read, transferTo`

### Methods declared in class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

## Field Details

### buf

protected char[] buf
The character buffer.

### pos

protected int pos
The current buffer position.

### markedPos

protected int markedPos
The position of mark in buffer.

### count

protected int count
The index of the end of this buffer. There is no valid data at or beyond this index.

## Constructor Details

### CharArrayReader

public CharArrayReader(char[] buf)
Creates a CharArrayReader from the specified array of chars.

Parameters:
  `buf` - Input buffer (not copied)

### CharArrayReader

public CharArrayReader(char[] buf, int offset, int length)
Creates a CharArrayReader from the specified array of chars.

The resulting reader will start reading at the given `offset`. The total number of `char` values that can be read from this reader will be either `length` or `buf.length-offset`, whichever is smaller.

Parameters:
  `buf` - Input buffer (not copied)
  `offset` - Offset of the first char to read
  `length` - Number of chars to read
Throws:
  `IllegalArgumentException` - If `offset` is negative or greater than `buf.length`, or if `length` is negative, or if the sum of these two values is negative.

## Method Details

### read

public int read() throws IOException
Reads a single character.

Overrides:
  `read` in class `Reader`
Returns:
  The character read, as an integer in the range 0 to 65535 (`0x00-0xffff`), or -1 if the end of the stream has been reached
Throws:
  `IOException` - If an I/O error occurs

### read

public int read(char[] cbuf, int off, int len) throws IOException
Reads characters into a portion of an array.

If `len` is zero, then no characters are read and `0` is returned; otherwise, there is an attempt to read at least one character. If no character is available because the stream is at its end, the value `-1` is returned; otherwise, at least one character is read and stored into `cbuf`.

Specified by:
  `read` in class `Reader`
Parameters:
  `cbuf` - Destination buffer
  `off` - Offset at which to start storing characters
  `len` - Maximum number of characters to read
Returns:
  The number of characters read, or -1 if the end of the stream has been reached
Throws:
  `IndexOutOfBoundsException` - If `off` is negative, or `len` is negative, or `len` is greater than `cbuf.length - off`
  `IOException` - If an I/O error occurs

### skip

public long skip(long n) throws IOException
Skips characters. If the stream is already at its end before this method is invoked, then no characters are skipped and zero is returned.

The `n` parameter may be negative, even though the `skip` method of the `Reader` superclass throws an exception in this case. If `n` is negative, then this method does nothing and returns `0`.

Overrides:
  `skip` in class `Reader`
Parameters:
  `n` - The number of characters to skip
Returns:
  The number of characters actually skipped
Throws:
  `IOException` - If an I/O error occurs

### ready

public boolean ready() throws IOException
Tells whether this stream is ready to be read. Character-array readers are always ready to be read.

Overrides:
  `ready` in class `Reader`
Returns:
  True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
Throws:
  `IOException` - If an I/O error occurs

### markSupported

public boolean markSupported()
Tells whether this stream supports the mark() operation, which it does.

Overrides:
  `markSupported` in class `Reader`
Returns:
  true if and only if this stream supports the mark operation.

### mark

public void mark(int readAheadLimit) throws IOException
Marks the present position in the stream. Subsequent calls to reset() will reposition the stream to this point.

Overrides:
  `mark` in class `Reader`
Parameters:
  `readAheadLimit` - Limit on the number of characters that may be read while still preserving the mark. Because the stream's input comes from a character array, there is no actual limit; hence this argument is ignored.
Throws:
  `IOException` - If an I/O error occurs

### reset

public void reset() throws IOException
Resets the stream to the most recent mark, or to the beginning if it has never been marked.

Overrides:
  `reset` in class `Reader`
Throws:
  `IOException` - If an I/O error occurs

### close

public void close()
Closes the stream and releases any system resources associated with it. Once the stream has been closed, further read(), ready(), mark(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect. This method will block while there is another thread blocking on the reader.

Specified by:
  `close` in interface `AutoCloseable`
Specified by:
  `close` in interface `Closeable`
Specified by:
  `close` in class `Reader`