File	Doc	Category	Size	Date	Package
HeadFilter.java	API Doc	Apache Ant 1.70	6553	Wed Dec 13 06:16:22 GMT 2006	org.apache.tools.ant.filters

HeadFilter

• java.lang.Object
  • BaseParamFilterReader

<headfilter lines="3"/>

<filterreader classname="org.apache.tools.ant.filters.HeadFilter">
<param name="lines" value="3"/>
</filterreader>

Fields Summary
private static final String	LINES_KEY Parameter name for the number of lines to be returned.
private static final String	SKIP_KEY Parameter name for the number of lines to be skipped.
private long	linesRead Number of lines currently read in.
private static final int	DEFAULT_NUM_LINES Default number of lines to show
private long	lines Number of lines to be returned in the filtered stream.
private long	skip Number of lines to be skipped.
private org.apache.tools.ant.util.LineTokenizer	lineTokenizer A line tokenizer
private String	line the current line from the input stream
private int	linePos the position in the current line

Constructors Summary
public HeadFilter() Constructor for "dummy" instances. see BaseFilterReader#BaseFilterReader() super();
public HeadFilter(Reader in) Creates a new filtered reader. param in A Reader object providing the underlying stream. Must not be null. super(in); lineTokenizer = new LineTokenizer(); lineTokenizer.setIncludeDelims(true);

Methods Summary
public java.io.Reader	chain(java.io.Reader rdr) Creates a new HeadFilter using the passed in Reader for instantiation. param rdr A Reader object providing the underlying stream. Must not be null. return a new filter based on this configuration, but filtering the specified reader HeadFilter newFilter = new HeadFilter(rdr); newFilter.setLines(getLines()); newFilter.setSkip(getSkip()); newFilter.setInitialized(true); return newFilter;
private long	getLines() Returns the number of lines to be returned in the filtered stream. return the number of lines to be returned in the filtered stream return lines;
private long	getSkip() Returns the number of lines to be skipped in the filtered stream. return the number of lines to be skipped in the filtered stream return skip;
private java.lang.String	headFilter(java.lang.String line) implements a head filter on the input stream linesRead++; if (skip > 0) { if ((linesRead - 1) < skip) { return null; } } if (lines > 0) { if (linesRead > (lines + skip)) { return null; } } return line;
private void	initialize() Scans the parameters list for the "lines" parameter and uses it to set the number of lines to be returned in the filtered stream. also scan for skip parameter. Parameter[] params = getParameters(); if (params != null) { for (int i = 0; i < params.length; i++) { if (LINES_KEY.equals(params[i].getName())) { lines = new Long(params[i].getValue()).longValue(); continue; } if (SKIP_KEY.equals(params[i].getName())) { skip = new Long(params[i].getValue()).longValue(); continue; } } }
public int	read() Returns the next character in the filtered stream. If the desired number of lines have already been read, the resulting stream is effectively at an end. Otherwise, the next character from the underlying stream is read and returned. return the next character in the resulting stream, or -1 if the end of the resulting stream has been reached exception IOException if the underlying stream throws an IOException during reading if (!getInitialized()) { initialize(); setInitialized(true); } while (line == null || line.length() == 0) { line = lineTokenizer.getToken(in); if (line == null) { return -1; } line = headFilter(line); linePos = 0; } int ch = line.charAt(linePos); linePos++; if (linePos == line.length()) { line = null; } return ch;
public void	setLines(long lines) Sets the number of lines to be returned in the filtered stream. param lines the number of lines to be returned in the filtered stream this.lines = lines;
public void	setSkip(long skip) Sets the number of lines to be skipped in the filtered stream. param skip the number of lines to be skipped in the filtered stream this.skip = skip;