- Java.io package classes
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- Java.io - InputStreamReader
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- Java.io - ObjectInputStream
- Java.io - ObjectInputStream.GetField
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- io - ObjectOutputStream.PutField
- Java.io - ObjectStreamClass
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- 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.PushbackReader.unread() Method
Description
The java.io.PushbackReader.unread(char[] cbuf) method pushes back an array of characters by copying it to the front of the pushback buffer. After this method returns, the next character to be read will have the value cbuf[0], the character after that will have the value cbuf[1], and so forth.
Declaration
Following is the declaration for java.io.PushbackReader.unread() method.
public void unread(char[] cbuf)
Parameters
cbuf − Character array to push back.
Return Value
This method does not return a value.
Exception
IOException − If there is insufficient room in the pushback buffer, or if some other I/O error occurs.
Example
The following example shows the usage of java.io.PushbackReader.unread() method.
package com.tutorialspoint; import java.io.*; public class PushbackReaderDemo { public static void main(String[] args) { String s = "Hello World"; // create a new StringReader StringReader sr = new StringReader(s); // create a new PushBack reader based on our string reader PushbackReader pr = new PushbackReader(sr, 20); try { // read the first five chars for (int i = 0; i < 5; i++) { char c = (char) pr.read(); System.out.print("" + c); } // change line System.out.println(); // create a new array to unread char cbuf[] = {'w', 'o', 'r', 'l', 'd'}; // unread into cbuf pr.unread(cbuf); // read five chars, which is what we unread from cbuf for (int i = 0; i < 5; i++) { char c = (char) pr.read(); System.out.print("" + c); } // close the stream pr.close(); } catch (IOException ex) { ex.printStackTrace(); } } }
Let us compile and run the above program, this will produce the following result −
Hello world
java_io_pushbackreader.htm
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