The Java PushbackInputStream class extends the functionality of an InputStream by allowing the ability to push back one byte that has been read and unread a byte. This class overrides methods from the InputStream class to provide this additional functionality.
Class declaration
Let's examine the declaration of the java.io.PushbackInputStream class:
Example
public class PushbackInputStream extends FilterInputStream
Class Methods
| Method | Description |
|---|---|
| int available() | It is used to return the number of bytes that can be read from the input stream. |
| int read() | It is used to read the next byte of data from the input stream. |
| boolean markSupported() | |
| void mark(int readlimit) | It is used to mark the current position in the input stream. |
| long skip(long x) | It is used to skip over and discard x bytes of data. |
| void unread(int b) | It is used to pushes back the byte by copying it to the pushback buffer. |
| void unread(byte[] b) | It is used to pushes back thearrayof byte by copying it to the pushback buffer. |
| void reset() | It is used to reset the input stream. |
| void close() | It is used to close the input stream. |
Example of PushbackInputStream class
Example
import java.io.*;
public class InputStreamExample {
public static void main(String[] args)throws Exception{
String srg = "1##2#34###12";
byte ary[] = srg.getBytes();
ByteArrayInputStream array = new ByteArrayInputStream(ary);
PushbackInputStream push = new PushbackInputStream(array);
int i;
while( (i = push.read())!= -1) {
if(i == '#') {
int j;
if( (j = push.read()) == '#'){
System.out.print("**");
}else {
push.unread(j);
System.out.print((char)i);
}
}else {
System.out.print((char)i);
}
}
}
}
Output:
Output
1**2#34**#12
