com.sun.enterprise.cli.framework.Pager Maven / Gradle / Ivy
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package com.sun.enterprise.cli.framework;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.Reader;
import java.io.Writer;
/**
* Pager.java
*
* @author Toby H Ferguson
* @version $Revision: 1.3 $
*/
class Pager {
private BufferedReader in;
private BufferedWriter out;
private int pageLength;
private String line;
/**
* Construct an object which will copy one pages worth of lines
* at a time from the input to the
* the output.
*
* No attempt is made under any circumstances to close the input
* or output.
*
* @param lines the number of lines in a page. A number less
* than 0 means copy all the input to the output.
* @param in the source of the copy operation
* @param out the destination of the copy operation
* @throws IOException if there's a problem reading from, or
* writing to, the source or destination
*/
Pager (int lines, Reader in, Writer out) throws IOException {
this.in = new BufferedReader(in);
this.out = new BufferedWriter(out);
pageLength = lines;
nextLine();
}
/**
* Copy the next page worth of lines from input to output
*/
void nextPage() throws IOException {
for (int i = 0; (pageLength < 0 || i < pageLength) && hasNext(); i++){
out.write(line);
out.newLine();
nextLine();
}
out.flush();
}
/**
* Indicate if there are lines left to be copied
* @return true iff there is at least one line left to be copied
*/
boolean hasNext() {
return line != null;
}
/**
* Get the next line and copy it inot the internal buffer so's
* we can answer the hasNext() question
*/
private void nextLine() throws IOException {
line = in.readLine();
}
}