- Java.io package classes
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- Java.io - BufferedInputStream
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- Java.io - FilterOutputStream
- Java.io - FilterReader
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- Java.io - InputStream
- Java.io - InputStreamReader
- Java.io - LineNumberInputStream
- Java.io - LineNumberReader
- Java.io - ObjectInputStream
- Java.io - ObjectInputStream.GetField
- Java.io - ObjectOutputStream
- io - ObjectOutputStream.PutField
- Java.io - ObjectStreamClass
- Java.io - ObjectStreamField
- Java.io - OutputStream
- Java.io - OutputStreamWriter
- Java.io - PipedInputStream
- Java.io - PipedOutputStream
- Java.io - PipedReader
- Java.io - PipedWriter
- Java.io - PrintStream
- Java.io - PrintWriter
- Java.io - PushbackInputStream
- Java.io - PushbackReader
- Java.io - RandomAccessFile
- Java.io - Reader
- Java.io - SequenceInputStream
- Java.io - SerializablePermission
- Java.io - StreamTokenizer
- Java.io - StringBufferInputStream
- Java.io - StringReader
- Java.io - StringWriter
- Java.io - Writer
- Java.io package extras
- Java.io - Interfaces
- Java.io - Exceptions
- Java.io package Useful Resources
- Java.io - Discussion
Java.io.PushbackInputStream.unread() Method
Description
The java.io.PushbackInputStream.unread(byte[] b) method pushes back an array of bytes by copying it to the front of the pushback buffer. After this method returns, the next byte to be read will have the value b[0], the byte after that will have the value b[1], and so forth.
Declaration
Following is the declaration for java.io.PushbackInputStream.unread() method.
public void unread(byte[] b)
Parameters
b − The byte array to push back.
Return Value
This method does not return a value.
Exception
IOException − If there is not enough room in the pushback buffer for the specified number of bytes, or this input stream has been closed by invoking its close() method.
Example
The following example shows the usage of java.io.PushbackInputStream.unread() method.
package com.tutorialspoint; import java.io.*; public class PushbackInputStreamDemo { public static void main(String[] args) { // declare a buffer and initialize its size: byte[] arrByte = new byte[1024]; // create an array for our message byte[] byteArray = new byte[]{'H', 'e', 'l', 'l', 'o',}; // create object of PushbackInputStream class for specified stream InputStream is = new ByteArrayInputStream(byteArray); PushbackInputStream pis = new PushbackInputStream(is, 10); try { // read from the buffer one character at a time for (int i = 0; i < byteArray.length; i++) { // read a char into our array arrByte[i] = (byte) pis.read(); // display the read byte System.out.print((char) arrByte[i]); } // change line System.out.println(); // create a new byte array to be unread byte[] b = {'W', 'o', 'r', 'l', 'd'}; // unread the byte array pis.unread(b); // read again from the buffer one character at a time for (int i = 0; i < byteArray.length; i++) { // read a char into our array arrByte[i] = (byte) pis.read(); // display the read byte System.out.print((char) arrByte[i]); } } catch (Exception ex) { ex.printStackTrace(); } } }
Let us compile and run the above program, this will produce the following result −
Hello World