[Chapter 24] 24.55 java.io.PushbackReader (JDK 1.1)

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| Chapter 24 The java.io Package |

## 24.55 java.io.PushbackReader (JDK 1.1)

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This class is a character input stream that uses another input stream as its input source, and adds the ability to push characters back onto the stream. This feature is often useful when writing parsers.

When you create a `PushbackReader` stream, you specify the stream to be read from, and may optionally specify the size of the pushback buffer--i.e., the number of characters that may be pushed back onto the stream or "unread." If you do not specify a size for this buffer, the default size is one character.

`PushbackReader` inherits or overrides all the standard `Reader` methods, and also adds three `unread()` methods that are used to push a single character, an array of characters, or a portion of an array of characters back onto the stream.

This class is the character stream analog of `PushbackInputStream`.

    public class PushbackReader extends FilterReader {
        // Public Constructors
                public PushbackReader(Reader in, int size);
                public PushbackReader(Reader in);
        // Public Instance Methods
                public void close() throws IOException;  // Overrides FilterReader
                public boolean markSupported();  // Overrides FilterReader
                public int read() throws IOException;  // Overrides FilterReader
                public int read(char[] cbuf, int off, int len) throws IOException;  // Overrides FilterReader
                public boolean ready() throws IOException;  // Overrides FilterReader
                public void unread(int c) throws IOException;
                public void unread(char[] cbuf, int off, int len) throws IOException;
                public void unread(char[] cbuf) throws IOException;
    }

### Hierarchy:

Object->Reader->FilterReader->PushbackReader

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