How can I get this code to display 20 lines

Question

I need to get this code I have written to display 20 lines at a time, then the 20 using the Enter key.
How would I approach this?
I thought of making a RandomAcessFile object, but that seems like overthinking the problem, and I'm not sure that I could get that to work anyway.
import java.io.*;
public class ReadIt
public static void main(String[] args)
     throws IOException
          System.out.println ("Enter The Desired .java Filename.");
          System.out.println ("Do not add the .java extention.");
          String fname;
          EasyIn type = new EasyIn();
          fname = type.readString();
          String fndotjava = new String(fname + ".java");
          //System.out.println (fndotjava);
          File inFile = new File(fndotjava);
          InputStream istream;
          OutputStream ostream;
          istream = new FileInputStream(inFile);
          ostream = System.out;
          int c;
          try
                 while((c = istream.read()) != -1)
                       ostream.write(c);
          catch(IOException e)
                 System.out.println("Error: " + e.getMessage());      
          finally
                istream.close();
                ostream.close();                 
}Thanks
Brad

Answer 1

Well, a RandomAccessFile together with a counter should work. However, you can also achieve this by buffering the input rather than writing it directly out
java.util.Vector vect = new java.util.Vector();
try{
     while((c = istream.read()) != -1){
         vect.append(c);
catch(IOException e){
     System.out.println("Error: " + e.getMessage());      
finally{
     istream.close();                 
}     with the help of
java.util.Vector.size() and
java.util.Vector.elementAt(int index)
you are able to display only 20 lines at a time, you just need the additional code for reading System.in
public static void prompt(String s){
    System.out.print(s + " ");
    System.out.flush();
  public static String readData ( BufferedReader in)  {
    boolean verfuegbar = true;
    while ( verfuegbar){
      try{
        S = in.readLine();
        if ( S != null)verfuegbar = false ;
      catch (IOException e){System.out.print (e);}
    return S;
  }now it should work with
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
prompt("return for continuing");
int twentscount = 0;
int count = 0;
do{
   while( count < 20 && twentscount+count < vect.size() ){
       outstream.write(vect.elementAt(twentscount + count).toString() );
       count++;
prompt("return");
readData(in);
twentscount += 20;
count = 0;
while(twentscount + count < vect.size());sure, this is code from head, and you can make many changes (e.g. instead of using twentscount use the modulo (%) operator saving one variable (while count % 20 != 0 ).
I'm also not sure if it will definitly run , since i haven't tested it (especialy for index borders).
I hope this will give you enough hints for this possible solution.
Adrian