Java.io.PushbackInputStream Class


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Introduction

The Java.io.PushbackInputStream class adds functionality to another input stream, namely the ability to "push back" or "unread" one byte.

Class declaration

Following is the declaration for Java.io.PushbackInputStream class −

public class PushbackInputStream
   extends FilterInputStream

Field

Following are the fields for Java.io.PushbackInputStream class −

  • protected byte[] buf − This is the pushback buffer.

  • protected int pos − This is the position within the pushback buffer from which the next byte will be read.

  • protected InputStream in − This is the input stream to be filtered.

Class constructors

Sr.No. Constructor & Description
1

PushbackInputStream(InputStream in)

This creates a PushbackInputStream and saves its argument, the input stream in, for later use.

2

PushbackInputStream(InputStream in, int size)

This creates a PushbackInputStream with a pushback buffer of the specified size, and saves its argument, the input stream in, for later use.

Class methods

Sr.No. Method & Description
1 int available()

This method returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream.

2 void close()

This method closes this input stream and releases any system resources associated with the stream.

3 void mark(int readlimit)

This method marks the current position in this input stream.

4 boolean markSupported()

This method tests if this input stream supports the mark and reset methods, which it does not.

5 int read()

This method reads the next byte of data from this input stream.

6 int read(byte[] b, int off, int len)

This method reads up to len bytes of data from this input stream into an array of bytes.

7 void reset()

This method repositions this stream to the position at the time the mark method was last called on this input stream.

8 long skip(long n)

This method skips over and discards n bytes of data from this input stream.

9 void unread(byte[] b)

This method pushes back an array of bytes by copying it to the front of the pushback buffer.

10 void unread(byte[] b, int off, int len)

This method pushes back a portion of an array of bytes by copying it to the front of the pushback buffer.

11 void unread(int b)

This method pushes back a byte by copying it to the front of the pushback buffer.

Methods inherited

This class inherits methods from the following classes −

  • Java.io.FilterInputStream
  • Java.io.Object
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