| java.lang.Object | |
| ↳ | java.io.Reader | 
|  Known Direct Subclasses | 
|  Known Indirect Subclasses | 
The base class for all readers. A reader is a means of reading data from a source in a character-wise manner. Some readers also support marking a position in the input and returning to this position later.
 This abstract class does not provide a fully working implementation, so it needs to be subclassed, and at least the read(char[], int, int) and close() methods needs to be overridden. Overriding some of the non-abstract methods is also often advised, since it might result in higher efficiency. 
Many specialized readers for purposes like reading from a file already exist in this package.
| Fields | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|  | lock | The object used to synchronize access to the reader. | |||||||||
| Protected Constructors | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|  | 
           Constructs a new 
            Readerwiththisas the object used to synchronize critical sections. | ||||||||||
|  | 
           Constructs a new 
            Readerwithlockused to synchronize critical sections. | ||||||||||
| Public Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|  | 
           Closes this reader.
           | ||||||||||
|  | 
           Sets a mark position in this reader.
           | ||||||||||
|  | 
           Indicates whether this reader supports the 
            mark()andreset()methods. | ||||||||||
|  | 
           Reads a single character from this reader and returns it as an integer with the two higher-order bytes set to 0.
           | ||||||||||
|  | 
           Reads at most 
            countcharacters from this reader and stores them atoffsetin the character arraybuf. | ||||||||||
|  | 
           Reads characters and puts them into the 
            targetcharacter buffer. | ||||||||||
|  | 
           Reads characters from this reader and stores them in the character array 
            bufstarting at offset 0. | ||||||||||
|  | 
           Indicates whether this reader is ready to be read without blocking.
           | ||||||||||
|  | 
           Resets this reader's position to the last 
            mark()location. | ||||||||||
|  | 
           Skips 
            charCountcharacters in this reader. | ||||||||||
| [Expand] 
           Inherited Methods
           | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|  From class java.lang.Object | |||||||||||
|  From interface java.io.Closeable | |||||||||||
|  From interface java.lang.Readable | |||||||||||
Constructs a new Reader with this as the object used to synchronize critical sections. 
Constructs a new Reader with lock used to synchronize critical sections.
| lock | the Objectused to synchronize critical sections. | 
|---|
| NullPointerException | if lockisnull. | 
|---|
Closes this reader. Implementations of this method should free any resources associated with the reader.
| IOException | if an error occurs while closing this reader. | 
|---|
Sets a mark position in this reader. The parameter readLimit indicates how many characters can be read before the mark is invalidated. Calling reset() will reposition the reader back to the marked position if readLimit has not been surpassed. 
 This default implementation simply throws an IOException; subclasses must provide their own implementation.
| readLimit | the number of characters that can be read before the mark is invalidated. | 
|---|
| IllegalArgumentException | if readLimit < 0. | 
|---|---|
| IOException | if an error occurs while setting a mark in this reader. | 
Indicates whether this reader supports the mark() and reset() methods. This default implementation returns false.
false. Reads a single character from this reader and returns it as an integer with the two higher-order bytes set to 0. Returns -1 if the end of the reader has been reached.
| IOException | if this reader is closed or some other I/O error occurs. | 
|---|
Reads at most count characters from this reader and stores them at offset in the character array buf. Returns the number of characters actually read or -1 if the end of the reader has been reached.
| buf | the character array to store the characters read. | 
|---|---|
| offset | the initial position in bufferto store the characters read from this reader. | 
| count | the maximum number of characters to read. | 
| IOException | if this reader is closed or some other I/O error occurs. | 
|---|
Reads characters and puts them into the target character buffer.
| target | the destination character buffer. | 
|---|
target or -1 if the end of this reader has been reached before a character has been read.| IOException | if any I/O error occurs while reading from this reader. | 
|---|---|
| NullPointerException | if targetisnull. | 
| ReadOnlyBufferException | if targetis read-only. | 
Reads characters from this reader and stores them in the character array buf starting at offset 0. Returns the number of characters actually read or -1 if the end of the reader has been reached.
| buf | character array to store the characters read. | 
|---|
| IOException | if this reader is closed or some other I/O error occurs. | 
|---|
Indicates whether this reader is ready to be read without blocking. Returns true if this reader will not block when read is called, false if unknown or blocking will occur. This default implementation always returns false.
false.| IOException | if this reader is closed or some other I/O error occurs. | 
|---|
Resets this reader's position to the last mark() location. Invocations of read() and skip() will occur from this new location. If this reader has not been marked, the behavior of reset() is implementation specific. This default implementation throws an IOException.
| IOException | always thrown in this default implementation. | 
|---|
Skips charCount characters in this reader. Subsequent calls of read methods will not return these characters unless reset is used. This method may perform multiple reads to read charCount characters.
| IllegalArgumentException | if charCount < 0. | 
|---|---|
| IOException | if this reader is closed or some other I/O error occurs. |