Package org.apache.commons.io.input

Class UnsynchronizedBufferedReader

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, java.lang.Readable
    public class UnsynchronizedBufferedReader
extends UnsynchronizedReader
    Wraps an existing Reader and buffers the input without any synchronization. Expensive interaction with the underlying reader is minimized, since most (smaller) requests can be satisfied by accessing the buffer alone. The drawback is that some extra space is required to hold the buffer and that copying takes place when filling that buffer, but this is usually outweighed by the performance benefits.

    A typical application pattern for the class looks like this: 

    
 UnsynchronizedBufferedReader buf = new UnsynchronizedBufferedReader(new FileReader("file"));

    Provenance: Apache Harmony's java.io.BufferedReader, renamed, and modified.

    Since:
    2.17.0
    See Also:
    BufferedReader, BufferedWriter

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private char[] buf
      The characters that can be read and refilled in bulk.
      private int end  
      private java.io.Reader in  
      private int mark  
      private int markLimit  
      private static char NUL  
      private int pos  

      • Fields inherited from class java.io.Reader

        lock

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) void chompNewline()
      Peeks at the next input character, refilling the buffer if necessary.
      void close()
      Closes this reader.
      private int fillBuf()
      Populates the buffer with data.
      void mark​(int markLimit)
      Sets a mark position in this reader.
      boolean markSupported()
      Tests whether this reader supports the mark(int) and reset() methods.
      int peek()
      Returns the next character in the current reader without consuming it.
      int peek​(char[] buf)
      Populates the buffer with the next buf.length characters in the current reader without consuming them.
      int read()
      Reads a single character from this reader and returns it with the two higher-order bytes set to 0.
      int read​(char[] buffer, int offset, int length)
      Reads at most length characters from this reader and stores them at offset in the character array buffer.
      java.lang.String readLine()
      Returns the next line of text available from this reader.
      boolean ready()
      Tests whether this reader is ready to be read without blocking.
      void reset()
      Resets this reader's position to the last mark() location.
      long skip​(long amount)
      Skips amount characters in this reader.

      • Methods inherited from class java.io.Reader

        nullReader, read, read, transferTo

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • in

        private final java.io.Reader in

      • buf

        private char[] buf
        The characters that can be read and refilled in bulk. We maintain three indices into this buffer: 
             { X X X X X X X X X X X X - - }
           ^     ^             ^
           |     |             |
         mark   pos           end

        Pos points to the next readable character. End is one greater than the last readable character. When pos == end, the buffer is empty and must be filled before characters can be read.

        Mark is the value pos will be set to on calls to reset(). Its value is in the range [0...pos]. If the mark is -1, the buffer cannot be reset.

        MarkLimit limits the distance between the mark and the pos. When this limit is exceeded, reset() is permitted (but not required) to throw an exception. For shorter distances, reset() shall not throw (unless the reader is closed).

      • pos

        private int pos

      • end

        private int end

      • mark

        private int mark

      • markLimit

        private int markLimit

    • Constructor Detail

      • UnsynchronizedBufferedReader

        public UnsynchronizedBufferedReader​(java.io.Reader in)
        Constructs a new BufferedReader on the Reader in. The buffer gets the default size (8 KB).
        Parameters:
        in - the Reader that is buffered.

      • UnsynchronizedBufferedReader

        public UnsynchronizedBufferedReader​(java.io.Reader in,
                                    int size)
        Constructs a new BufferedReader on the Reader in. The buffer size is specified by the parameter size.
        Parameters:
        in - the Reader that is buffered.
        size - the size of the buffer to allocate.
        Throws:
        java.lang.IllegalArgumentException - if size <= 0.

    • Method Detail

      • chompNewline

        final void chompNewline()
                 throws java.io.IOException
        Peeks at the next input character, refilling the buffer if necessary. If this character is a newline character ("\n"), it is discarded.
        Throws:
        java.io.IOException

      • close

        public void close()
           throws java.io.IOException
        Closes this reader. This implementation closes the buffered source reader and releases the buffer. Nothing is done if this reader has already been closed.
        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable
        Overrides:
        close in class UnsynchronizedReader
        Throws:
        java.io.IOException - if an error occurs while closing this reader.

      • fillBuf

        private int fillBuf()
             throws java.io.IOException
        Populates the buffer with data. It is an error to call this method when the buffer still contains data; ie. if pos < end.
        Returns:
        the number of bytes read into the buffer, or -1 if the end of the source stream has been reached.
        Throws:
        java.io.IOException

      • mark

        public void mark​(int markLimit)
          throws java.io.IOException
        Sets a mark position in this reader. The parameter markLimit indicates how many characters can be read before the mark is invalidated. Calling reset() will reposition the reader back to the marked position if markLimit has not been surpassed.
        Overrides:
        mark in class java.io.Reader
        Parameters:
        markLimit - the number of characters that can be read before the mark is invalidated.
        Throws:
        java.lang.IllegalArgumentException - if markLimit < 0.
        java.io.IOException - if an error occurs while setting a mark in this reader.
        See Also:
        markSupported(), reset()

      • markSupported

        public boolean markSupported()
        Tests whether this reader supports the mark(int) and reset() methods. This implementation returns true.
        Overrides:
        markSupported in class java.io.Reader
        Returns:
        true for BufferedReader.
        See Also:
        mark(int), reset()

      • peek

        public int peek()
         throws java.io.IOException
        Returns the next character in the current reader without consuming it. So the next call to read() will still return this value.
        Returns:
        the next character
        Throws:
        java.io.IOException - If an I/O error occurs

      • peek

        public int peek​(char[] buf)
         throws java.io.IOException
        Populates the buffer with the next buf.length characters in the current reader without consuming them. The next call to read() will still return the next value.
        Parameters:
        buf - the buffer to fill for the look ahead.
        Returns:
        the buffer itself
        Throws:
        java.io.IOException - If an I/O error occurs

      • read

        public int read()
         throws java.io.IOException
        Reads a single character from this reader and returns it with the two higher-order bytes set to 0. If possible, BufferedReader returns a character from the buffer. If there are no characters available in the buffer, it fills the buffer and then returns a character. It returns -1 if there are no more characters in the source reader.
        Overrides:
        read in class java.io.Reader
        Returns:
        the character read or -1 if the end of the source reader has been reached.
        Throws:
        java.io.IOException - if this reader is closed or some other I/O error occurs.

      • read

        public int read​(char[] buffer,
                int offset,
                int length)
         throws java.io.IOException
        Reads at most length characters from this reader and stores them at offset in the character array buffer. Returns the number of characters actually read or -1 if the end of the source reader has been reached. If all the buffered characters have been used, a mark has not been set and the requested number of characters is larger than this readers buffer size, BufferedReader bypasses the buffer and simply places the results directly into buffer.
        Specified by:
        read in class java.io.Reader
        Parameters:
        buffer - the character array to store the characters read.
        offset - the initial position in buffer to store the bytes read from this reader.
        length - the maximum number of characters to read, must be non-negative.
        Returns:
        number of characters read or -1 if the end of the source reader has been reached.
        Throws:
        java.lang.IndexOutOfBoundsException - if offset < 0 or length < 0, or if offset + length is greater than the size of buffer.
        java.io.IOException - if this reader is closed or some other I/O error occurs.

      • readLine

        public java.lang.String readLine()
                          throws java.io.IOException
        Returns the next line of text available from this reader. A line is represented by zero or more characters followed by LF, CR, "\r\n" or the end of the reader. The string does not include the newline sequence.
        Returns:
        the contents of the line or null if no characters were read before the end of the reader has been reached.
        Throws:
        java.io.IOException - if this reader is closed or some other I/O error occurs.

      • ready

        public boolean ready()
              throws java.io.IOException
        Tests whether this reader is ready to be read without blocking.
        Overrides:
        ready in class java.io.Reader
        Returns:
        true if this reader will not block when read is called, false if unknown or blocking will occur.
        Throws:
        java.io.IOException - if this reader is closed or some other I/O error occurs.
        See Also:
        read(), read(char[], int, int), readLine()

      • reset

        public void reset()
           throws java.io.IOException
        Resets this reader's position to the last mark() location. Invocations of read() and skip() will occur from this new location.
        Overrides:
        reset in class java.io.Reader
        Throws:
        java.io.IOException - if this reader is closed or no mark has been set.
        See Also:
        mark(int), markSupported()

      • skip

        public long skip​(long amount)
          throws java.io.IOException
        Skips amount characters in this reader. Subsequent read()s will not return these characters unless reset() is used. Skipping characters may invalidate a mark if markLimit is surpassed.
        Overrides:
        skip in class UnsynchronizedReader
        Parameters:
        amount - the maximum number of characters to skip.
        Returns:
        the number of characters actually skipped.
        Throws:
        java.lang.IllegalArgumentException - if amount < 0.
        java.io.IOException - if this reader is closed or some other I/O error occurs.
        See Also:
        mark(int), markSupported(), reset()