[Chapter 24] 24.57 java.io.Reader (JDK 1.1)

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| Chapter 24 The java.io Package |

## 24.57 java.io.Reader (JDK 1.1)

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This abstract class is the superclass of all character input streams. It is an analog to `InputStream`, which is the superclass of all byte input streams. `Reader` defines the basic methods that all character output streams provide.

`read()` returns a single character or an array (or subarray) of characters, blocking if necessary. It returns `-1` if the end of the stream has been reached. `ready()` returns `true` if there are characters available for reading. If `ready()` returns `true`, the next call to `read()` is guaranteed not to block. `close()` closes the character input stream. `skip()` skips a specified number of characters in the input stream. If `markSupported()` returns `true`, then `mark()` "marks" a position in the stream and, if necessary, creates a look-ahead buffer of the specified size. Future calls to `reset()` restore the stream to the marked position, if they occur within the specified look-ahead limit. Note that not all stream types support this mark-and-reset functionality.

To create a subclass of `Reader`, you need only implement the three-argument version of `read()` and `close()`. Most subclasses implement additional methods as well, however.

    public abstract class Reader extends Object {
        // Protected Constructors
                protected Reader();
                protected Reader(Object lock);
        // Protected Instance Variables
                protected Object lock;
        // Public Instance Methods
                public abstract void close() throws IOException;
                public void mark(int readAheadLimit) throws IOException;
                public boolean markSupported();
                public int read() throws IOException;
                public int read(char[] cbuf) throws IOException;
                public abstract int read(char[] cbuf, int off, int len) throws IOException;
                public boolean ready() throws IOException;
                public void reset() throws IOException;
                public long skip(long n) throws IOException;
    }

### Extended By:

BufferedReader, CharArrayReader, FilterReader, InputStreamReader, PipedReader, StringReader

### Passed To:

BufferedReader(), FilterReader(), LineNumberReader(), PushbackReader(), StreamTokenizer()

### Type Of:

FilterReader.in

java.io.RandomAccessFile (JDK 1.0) |  | java.io.SequenceInputStream (JDK 1.0)