The Java PushbackReader class functions as a reader for character streams with the capability to push a character back into the stream. This class extends the FilterReader class to provide this functionality.
Class declaration
Let's examine the declaration of the Java class called PushbackReader in the java.io package:
Example
public class PushbackReader extends FilterReader
Class Methods
| Method | Description |
|---|---|
| int read() | It is used to read a single character. |
| void mark(int readAheadLimit) | It is used to mark the present position in a stream. |
| boolean ready() | It is used to tell whether the stream is ready to be read. |
| boolean markSupported() | It is used to tell whether the stream supports mark() operation. |
| long skip(long n) | It is used to skip the character. |
| void unread (int c) | It is used to pushes back the character by copying it to the pushback buffer. |
| void unread (char[] cbuf) | It is used to pushes back an array of character by copying it to the pushback buffer. |
| void reset() | It is used to reset the stream. |
| void close() | It is used to close the stream. |
Example of PushbackReader class
Example
import java.io.*;
public class ReaderExample{
public static void main(String[] args) throws Exception {
char ary[] = {'1','-','-','2','-','3','4','-','-','-','5','6'};
CharArrayReader reader = new CharArrayReader(ary);
PushbackReader push = new PushbackReader(reader);
int i;
while( (i = push.read())!= -1) {
if(i == '-') {
int j;
if( (j = push.read()) == '-'){
System.out.print("#*");
}else {
push.unread(j); // push back single character
System.out.print((char)i);
}
}else {
System.out.print((char)i);
}
}
}
}
Output
Output
1#*2-34#*-56
