/*:-PushbackInputStream is used on an input stream to allow a byte to be read and then returned to the stream .

:-It is helpful for parser designing .*/

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.PushbackInputStream;

class UsingPushBackInputStream{

public static void main(String ar[])throws IOException {

String s = "if(a == 4)a = 0";

byte buf[] = s.getBytes();

ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(buf);

PushbackInputStream pushbackInputStream = new PushbackInputStream(byteArrayInputStream);

int no;

while ((no = pushbackInputStream.read())!= -1){

switch (no){

case'=':

if ((no = pushbackInputStream.read())== '='){

// System.out.print(no);

System.out.print("comparison");

}

else

{

System.out.print("assignment");

pushbackInputStream.unread(no);

}

break;

default:

System.out.print((char)no);

}

}

}

}