BufferedReader (Java SE 10 & JDK 10 ) (original) (raw)

java.lang.Object
- java.io.Reader
- - java.io.BufferedReader
All Implemented Interfaces:
[Closeable](../../java/io/Closeable.html "interface in java.io"), [AutoCloseable](../../java/lang/AutoCloseable.html "interface in java.lang"), [Readable](../../java/lang/Readable.html "interface in java.lang")
Direct Known Subclasses:
[LineNumberReader](../../java/io/LineNumberReader.html "class in java.io")

public class BufferedReader
extends Reader
Reads text from a character-input stream, buffering characters so as to provide for the efficient reading of characters, arrays, and lines.
The buffer size may be specified, or the default size may be used. The default is large enough for most purposes.
In general, each read request made of a Reader causes a corresponding read request to be made of the underlying character or byte stream. It is therefore advisable to wrap a BufferedReader around any Reader whose read() operations may be costly, such as FileReaders and InputStreamReaders. For example,
BufferedReader in
= new BufferedReader(new FileReader("foo.in"));

will buffer the input from the specified file. Without buffering, each invocation of read() or readLine() could cause bytes to be read from the file, converted into characters, and then returned, which can be very inefficient.
Programs that use DataInputStreams for textual input can be localized by replacing each DataInputStream with an appropriate BufferedReader.
Since:
1.1
See Also:
FileReader, InputStreamReader, Files.newBufferedReader(java.nio.file.Path, java.nio.charset.Charset)

Field Summary

 * ### Fields declared in class java.io.[Reader](../../java/io/Reader.html "class in java.io")  
 `[lock](../../java/io/Reader.html#lock)`

Constructor Summary

Constructors

Constructor	Description
BufferedReader(Reader in)	Creates a buffering character-input stream that uses a default-sized input buffer.
BufferedReader(Reader in, int sz)	Creates a buffering character-input stream that uses an input buffer of the specified size.

Method Summary

All Methods Instance Methods Concrete Methods

Modifier and Type	Method	Description
Stream<String>	lines()	Returns a Stream, the elements of which are lines read from this BufferedReader.
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.
String	readLine()	Reads a line of text.
boolean	ready()	Tells whether this stream is ready to be read.
void	reset()	Resets the stream to the most recent mark.
long	skip(long n)	Skips characters.

   * ### Methods declared in class java.lang.[Object](../../java/lang/Object.html "class in java.lang")  
   `[clone](../../java/lang/Object.html#clone%28%29), [equals](../../java/lang/Object.html#equals%28java.lang.Object%29), [finalize](../../java/lang/Object.html#finalize%28%29), [getClass](../../java/lang/Object.html#getClass%28%29), [hashCode](../../java/lang/Object.html#hashCode%28%29), [notify](../../java/lang/Object.html#notify%28%29), [notifyAll](../../java/lang/Object.html#notifyAll%28%29), [toString](../../java/lang/Object.html#toString%28%29), [wait](../../java/lang/Object.html#wait%28%29), [wait](../../java/lang/Object.html#wait%28long%29), [wait](../../java/lang/Object.html#wait%28long,int%29)`  
   * ### Methods declared in class java.io.[Reader](../../java/io/Reader.html "class in java.io")  
   `[close](../../java/io/Reader.html#close%28%29), [read](../../java/io/Reader.html#read%28char%5B%5D%29), [read](../../java/io/Reader.html#read%28java.nio.CharBuffer%29), [transferTo](../../java/io/Reader.html#transferTo%28java.io.Writer%29)`

Constructor Detail

 * #### BufferedReader  
 public BufferedReader([Reader](../../java/io/Reader.html "class in java.io") in,  
                       int sz)  
 Creates a buffering character-input stream that uses an input buffer of the specified size.  
 Parameters:  
 `in` \- A Reader  
 `sz` \- Input-buffer size  
 Throws:  
 `[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang")` \- If `sz <= 0`  
 * #### BufferedReader  
 public BufferedReader([Reader](../../java/io/Reader.html "class in java.io") in)  
 Creates a buffering character-input stream that uses a default-sized input buffer.  
 Parameters:  
 `in` \- A Reader

Method Detail

* #### read  
public int read()  
         throws [IOException](../../java/io/IOException.html "class in java.io")  
Reads a single character.  
Overrides:  
`[read](../../java/io/Reader.html#read%28%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")`  
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](../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs  
* #### read  
public int read(char[] cbuf,  
                int off,  
                int len)  
         throws [IOException](../../java/io/IOException.html "class in java.io")  
Reads characters into a portion of an array.  
 This method implements the general contract of the corresponding`[read](../../java/io/Reader.html#read%28char%5B%5D,int,int%29)` method of the`[Reader](../../java/io/Reader.html "class in java.io")` class. As an additional convenience, it attempts to read as many characters as possible by repeatedly invoking the `read` method of the underlying stream. This iterated`read` continues until one of the following conditions becomes true:  
         * The specified number of characters have been read,  
         * The `read` method of the underlying stream returns`-1`, indicating end-of-file, or  
         * The `ready` method of the underlying stream returns `false`, indicating that further input requests would block.  
 If the first `read` on the underlying stream returns`-1` to indicate end-of-file then this method returns`-1`. Otherwise this method returns the number of characters actually read.  
 Subclasses of this class are encouraged, but not required, to attempt to read as many characters as possible in the same fashion.  
 Ordinarily this method takes characters from this stream's character buffer, filling it from the underlying stream as necessary. If, however, the buffer is empty, the mark is not valid, and the requested length is at least as large as the buffer, then this method will read characters directly from the underlying stream into the given array. Thus redundant `BufferedReader`s will not copy data unnecessarily.  
Specified by:  
`[read](../../java/io/Reader.html#read%28char%5B%5D,int,int%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")`  
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:  
`[IOException](../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs  
`[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang")` \- If an I/O error occurs  
* #### readLine  
public [String](../../java/lang/String.html "class in java.lang") readLine()  
                throws [IOException](../../java/io/IOException.html "class in java.io")  
Reads a line of text. A line is considered to be terminated by any one of a line feed ('\\n'), a carriage return ('\\r'), a carriage return followed immediately by a line feed, or by reaching the end-of-file (EOF).  
Returns:  
A String containing the contents of the line, not including any line-termination characters, or null if the end of the stream has been reached without reading any characters  
Throws:  
`[IOException](../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs  
See Also:  
[Files.readAllLines(java.nio.file.Path, java.nio.charset.Charset)](../../java/nio/file/Files.html#readAllLines%28java.nio.file.Path,java.nio.charset.Charset%29)  
* #### skip  
public long skip(long n)  
          throws [IOException](../../java/io/IOException.html "class in java.io")  
Skips characters.  
Overrides:  
`[skip](../../java/io/Reader.html#skip%28long%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")`  
Parameters:  
`n` \- The number of characters to skip  
Returns:  
The number of characters actually skipped  
Throws:  
`[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang")` \- If `n` is negative.  
`[IOException](../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs  
* #### ready  
public boolean ready()  
              throws [IOException](../../java/io/IOException.html "class in java.io")  
Tells whether this stream is ready to be read. A buffered character stream is ready if the buffer is not empty, or if the underlying character stream is ready.  
Overrides:  
`[ready](../../java/io/Reader.html#ready%28%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")`  
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](../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs  
* #### markSupported  
public boolean markSupported()  
Tells whether this stream supports the mark() operation, which it does.  
Overrides:  
`[markSupported](../../java/io/Reader.html#markSupported%28%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")`  
Returns:  
true if and only if this stream supports the mark operation.  
* #### mark  
public void mark(int readAheadLimit)  
          throws [IOException](../../java/io/IOException.html "class in java.io")  
Marks the present position in the stream. Subsequent calls to reset() will attempt to reposition the stream to this point.  
Overrides:  
`[mark](../../java/io/Reader.html#mark%28int%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")`  
Parameters:  
`readAheadLimit` \- Limit on the number of characters that may be read while still preserving the mark. An attempt to reset the stream after reading characters up to this limit or beyond may fail. A limit value larger than the size of the input buffer will cause a new buffer to be allocated whose size is no smaller than limit. Therefore large values should be used with care.  
Throws:  
`[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang")` \- If `readAheadLimit < 0`  
`[IOException](../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs  
* #### reset  
public void reset()  
           throws [IOException](../../java/io/IOException.html "class in java.io")  
Resets the stream to the most recent mark.  
Overrides:  
`[reset](../../java/io/Reader.html#reset%28%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")`  
Throws:  
`[IOException](../../java/io/IOException.html "class in java.io")` \- If the stream has never been marked, or if the mark has been invalidated  
* #### lines  
public [Stream](../../java/util/stream/Stream.html "interface in java.util.stream")<[String](../../java/lang/String.html "class in java.lang")> lines()  
Returns a `Stream`, the elements of which are lines read from this `BufferedReader`. The [Stream](../../java/util/stream/Stream.html "interface in java.util.stream") is lazily populated, i.e., read only occurs during the[terminal stream operation](../util/stream/package-summary.html#StreamOps).  
 The reader must not be operated on during the execution of the terminal stream operation. Otherwise, the result of the terminal stream operation is undefined.  
 After execution of the terminal stream operation there are no guarantees that the reader will be at a specific position from which to read the next character or line.  
 If an [IOException](../../java/io/IOException.html "class in java.io") is thrown when accessing the underlying`BufferedReader`, it is wrapped in an [UncheckedIOException](../../java/io/UncheckedIOException.html "class in java.io") which will be thrown from the `Stream` method that caused the read to take place. This method will return a Stream if invoked on a BufferedReader that is closed. Any operation on that stream that requires reading from the BufferedReader after it is closed, will cause an UncheckedIOException to be thrown.  
Returns:  
a `Stream<String>` providing the lines of text described by this `BufferedReader`  
Since:  
1.8

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BufferedReader (Java SE 10 & JDK 10 ) (original) (raw)

Field Summary

Constructor Summary

Method Summary

Constructor Detail

Method Detail