Class NonBlockingReader
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Readable
- Direct Known Subclasses:
NonBlockingPumpReader
,NonBlockingReaderImpl
The NonBlockingReader class extends the standard Reader class to provide non-blocking read operations. Unlike standard readers, which block until data is available or the end of the stream is reached, non-blocking readers can be configured to return immediately or after a specified timeout if no data is available.
This class is particularly useful for terminal applications that need to perform other tasks while waiting for user input, or that need to implement features like input timeouts or polling.
The class defines two special return values:
EOF
(-1) - Indicates that the end of the stream has been reachedREAD_EXPIRED
(-2) - Indicates that the read operation timed out
Implementations of this class typically use a separate thread to handle
blocking I/O operations, allowing the main thread to continue execution.
The shutdown()
method can be used to terminate this background
thread when it is no longer needed.
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Field Summary
Fields -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint
int
peek
(long timeout) Peeks to see if there is a byte waiting in the input stream without actually consuming the byte.int
read()
int
read
(char[] b, int off, int len) This version of read() is very specific to jline's purposes, it will always always return a single byte at a time, rather than filling the entire buffer.int
read
(long timeout) Attempts to read a character from the input stream for a specific period of time.protected abstract int
read
(long timeout, boolean isPeek) Attempts to read a character from the input stream for a specific period of time.int
readBuffered
(char[] b) abstract int
readBuffered
(char[] b, int off, int len, long timeout) int
readBuffered
(char[] b, long timeout) void
shutdown()
Shuts down the thread that is handling blocking I/O.Methods inherited from class java.io.Reader
close, mark, markSupported, nullReader, read, read, ready, reset, skip, transferTo
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Field Details
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EOF
public static final int EOF- See Also:
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READ_EXPIRED
public static final int READ_EXPIRED- See Also:
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Constructor Details
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NonBlockingReader
public NonBlockingReader()
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Method Details
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shutdown
public void shutdown()Shuts down the thread that is handling blocking I/O.This method terminates the background thread that is used to handle blocking I/O operations. This allows the application to clean up resources and prevent thread leaks when the reader is no longer needed.
Note that if the thread is currently blocked waiting for I/O, it will not actually shut down until the I/O is received or the thread is interrupted. In some implementations, this method may interrupt the thread to force it to shut down immediately.
After calling this method, the reader should not be used anymore, as subsequent read operations may fail or block indefinitely.
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read
- Overrides:
read
in classReader
- Throws:
IOException
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peek
Peeks to see if there is a byte waiting in the input stream without actually consuming the byte.- Parameters:
timeout
- The amount of time to wait, 0 == forever- Returns:
- -1 on eof, -2 if the timeout expired with no available input or the character that was read (without consuming it).
- Throws:
IOException
- if anything wrong happens
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read
Attempts to read a character from the input stream for a specific period of time.- Parameters:
timeout
- The amount of time to wait for the character- Returns:
- The character read, -1 if EOF is reached, or -2 if the read timed out.
- Throws:
IOException
- if anything wrong happens
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read
This version of read() is very specific to jline's purposes, it will always always return a single byte at a time, rather than filling the entire buffer.- Specified by:
read
in classReader
- Parameters:
b
- the bufferoff
- the offset in the bufferlen
- the maximum number of chars to read- Throws:
IOException
- if anything wrong happens
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readBuffered
- Throws:
IOException
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readBuffered
- Throws:
IOException
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readBuffered
- Throws:
IOException
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available
public int available() -
read
Attempts to read a character from the input stream for a specific period of time.- Parameters:
timeout
- The amount of time to wait for the characterisPeek
-true
if the character read must not be consumed- Returns:
- The character read, -1 if EOF is reached, or -2 if the read timed out.
- Throws:
IOException
- if anything wrong happens
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