PushbackReader in Java

PushbackReader class is a character-stream reader that allows characters to be pushed back into the stream. It allows you to push back the read characters into the Reader. These characters will then be read again the next time you call read().

The call to unread() pushes a character back into the PushbackReader.

Constructors

Methods

package com.java.io;

import java.io.FileReader;
import java.io.IOException;
import java.io.PushbackReader;

public class PushbackReaderExample {

    public static void main(String[] args) {

        FileReader fileReader = null;
        PushbackReader pushbackReader = null;
        try {
            fileReader = new FileReader("/Test/TestFolder/test-file.txt");
            pushbackReader = new PushbackReader(fileReader);
            char c[] = new char[15];
            System.out.print("Characters read:");

            if (pushbackReader.ready()) {
                pushbackReader.read(c);
                for (int i = 0; i < 15; i++) {
                    System.out.print(c[i]);
                }
            }

            System.out.println("");
            System.out.println("PushedBack Character:" + c[0]);
            pushbackReader.unread(c[0]);
            System.out.print("PushedBack Character read again:");
            if (pushbackReader.ready()) {
                System.out.print((char) pushbackReader.read());
            }

        } catch (IOException ex) {
            ex.printStackTrace();
        } finally {
            if (fileReader != null)
                try {
                    fileReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            if (pushbackReader != null)
                try {
                    pushbackReader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
        }

    }

}

Characters read:Test Data
PushedBack Character:T
PushedBack Character read again:T

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Java I/O Basics