PushbackInputStream 

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

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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