Mega Code Archive
0237 PushbackInputStream
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PushbackInputStream allows a byte to be read and then returned to the stream. PushbackInputStream peeks what is coming from an input stream without disrupting it.
PushbackInputStream has the following constructors:
PushbackInputStream(InputStream inputStream)
creates a stream object that allows one byte to be returned to the input stream.
PushbackInputStream(InputStream inputStream, int numBytes)
creates a stream that has a pushback buffer that is numBytes long.
PushbackInputStream provides unread( ) method:
void unread(int ch)
pushes back the low-order byte of ch. This will be the next byte returned by a subsequent call to read( ).
void unread(byte buffer[ ])
returns the bytes in buffer.
void unread(byte buffer, int offset, int numChars)
pushes back numChars bytes beginning at offset from buffer.
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.PushbackInputStream;
public class Main {
public static void main(String args[]) throws IOException {
byte buf[] = "== = ".getBytes();
PushbackInputStream f = new PushbackInputStream(new ByteArrayInputStream(buf));
int c;
while ((c = f.read()) != -1) {
switch (c) {
case '=':
c = f.read();
if (c == '=')
System.out.print(".eq.");
else {
System.out.print("=");
f.unread(c);
}
break;
default:
System.out.print((char) c);
break;
}
}
}
}
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