Java/File Input Output/PushbackInputStream

Demonstrate unread().

   <source lang="java">

import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.PushbackInputStream; class PushbackInputStreamDemo {

 public static void main(String args[]) throws IOException {
   String s = "if (a == 4) a = 0;\n";
   byte buf[] = s.getBytes();
   ByteArrayInputStream in = new ByteArrayInputStream(buf);
   PushbackInputStream f = new PushbackInputStream(in);
   int c;
   while ((c = f.read()) != -1) {
     switch (c) {
     case "=":
       if ((c = f.read()) == "=")
         System.out.print(".eq.");
       else {
         System.out.print("<-");
         f.unread(c);
       }
       break;
     default:
       System.out.print((char) c);
       break;
     }
   }
 }

}

       </source>