Renderers use less memory when generating reports.

The previous implementation built the entire report as a single String. Testing
all rules on the JDK generates a report larger than 100M and that created a
spike in memory usage at the very end.


git-svn-id: https://pmd.svn.sourceforge.net/svnroot/pmd/trunk@4814 51baf565-9d33-0410-a72c-fc3788e3496d

pmd/etc/changelog.txt

@@ -42,6 +42,7 @@ Better 'create rule XML' panel in Designer.
 use of entrySet to iterate over Maps.
 1.6 added as a valid option for targetjdk.
 PMD now allows rules to use Type Resolution. This was referenced in patch 1257259.
+Renderers use less memory when generating reports.
 Performance Refactoring, XPath rules re-written as Java:
     AssignmentInOperand
     AvoidDollarSigns

pmd/src/net/sourceforge/pmd/PMD.java

@@ -17,6 +17,7 @@ import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
 import java.io.Reader;
 import java.io.UnsupportedEncodingException;
 import java.util.ArrayList;
@@ -274,7 +275,10 @@ public class PMD {
 
         try {
             Renderer r = opts.createRenderer();
-            System.out.println(r.render(ctx.getReport()));
+            OutputStreamWriter w = new OutputStreamWriter(System.out);
+            r.render(w, ctx.getReport());
+            w.flush();
+            System.out.println();
         } catch (Exception e) {
             System.out.println(e.getMessage());
             System.out.println(opts.usage());

pmd/src/net/sourceforge/pmd/ant/Formatter.java

@@ -127,8 +127,8 @@ public class Formatter {
     }
 
     private void outputReportTo(Writer writer, Report report, boolean consoleRenderer) throws IOException {
-        String renderedReport = getRenderer(consoleRenderer).render(report) + PMD.EOL;
+        getRenderer(consoleRenderer).render(writer, report);
-        writer.write(renderedReport, 0, renderedReport.length());
+        writer.write(PMD.EOL);
         writer.close();
     }
 

pmd/src/net/sourceforge/pmd/renderers/AbstractRenderer.java

@@ -1,5 +1,8 @@
 package net.sourceforge.pmd.renderers;
 
+import java.io.IOException;
+import java.io.StringWriter;
+
 import net.sourceforge.pmd.Report;
 
 public abstract class AbstractRenderer implements Renderer {
@@ -10,5 +13,14 @@ public abstract class AbstractRenderer implements Renderer {
         this.showSuppressedViolations = show;
     }
 
-    public abstract String render(Report report);
+    public String render(Report report) {
+        StringWriter w = new StringWriter();
+        try {
+            render(w, report);
+        } catch (IOException e) {
+            throw new Error("StringWriter doesn't throw IOException", e);
+        }
+        return w.toString();
+    }
+
 }

pmd/src/net/sourceforge/pmd/renderers/CSVRenderer.java

@@ -8,11 +8,13 @@ import net.sourceforge.pmd.PMD;
 import net.sourceforge.pmd.Report;
 import net.sourceforge.pmd.util.StringUtil;
 
+import java.io.IOException;
+import java.io.Writer;
 import java.util.Iterator;
 
-public class CSVRenderer extends AbstractRenderer implements Renderer {
+public class CSVRenderer extends AbstractRenderer {
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
         StringBuffer buf = new StringBuffer(300);
         quoteAndCommify(buf, "Problem");
         quoteAndCommify(buf, "Package");
@@ -23,15 +25,16 @@ public class CSVRenderer extends AbstractRenderer implements Renderer {
         quoteAndCommify(buf, "Rule set");
         quote(buf, "Rule");
         buf.append(PMD.EOL);
+        writer.write(buf.toString());
 
-        addViolations(report, buf);
+        addViolations(writer, report, buf);
-        return buf.toString();
     }
 
-	private void addViolations(Report report, StringBuffer buf) {
+	private void addViolations(Writer writer, Report report, StringBuffer buf) throws IOException {
 		int violationCount = 1;
 		IRuleViolation rv;
         for (Iterator i = report.iterator(); i.hasNext();) {
+            buf.setLength(0);
             rv = (IRuleViolation) i.next();
             quoteAndCommify(buf, Integer.toString(violationCount));
             quoteAndCommify(buf, rv.getPackageName());
@@ -42,6 +45,7 @@ public class CSVRenderer extends AbstractRenderer implements Renderer {
             quoteAndCommify(buf, rv.getRule().getRuleSetName());
             quote(buf, rv.getRule().getName());
             buf.append(PMD.EOL);
+            writer.write(buf.toString());
             violationCount++;
         }
 	}

pmd/src/net/sourceforge/pmd/renderers/EmacsRenderer.java

@@ -6,20 +6,23 @@ package net.sourceforge.pmd.renderers;
 import net.sourceforge.pmd.IRuleViolation;
 import net.sourceforge.pmd.Report;
 
+import java.io.IOException;
+import java.io.Writer;
 import java.util.Iterator;
 
-public class EmacsRenderer extends AbstractRenderer implements Renderer {
+public class EmacsRenderer extends AbstractRenderer {
 
     protected static final String EOL = System.getProperty("line.separator", "\n");
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
         StringBuffer buf = new StringBuffer();
         for (Iterator i = report.iterator(); i.hasNext();) {
             IRuleViolation rv = (IRuleViolation) i.next();
+            buf.setLength(0);
             buf.append(EOL).append(rv.getFilename());
             buf.append(':').append(Integer.toString(rv.getBeginLine()));
             buf.append(": ").append(rv.getDescription());
+            writer.write(buf.toString());
         }
-        return buf.toString();
     }
 }

pmd/src/net/sourceforge/pmd/renderers/HTMLRenderer.java

@@ -8,9 +8,11 @@ import net.sourceforge.pmd.PMD;
 import net.sourceforge.pmd.Report;
 import net.sourceforge.pmd.util.StringUtil;
 
+import java.io.IOException;
+import java.io.Writer;
 import java.util.Iterator;
 
-public class HTMLRenderer extends AbstractRenderer implements Renderer {
+public class HTMLRenderer extends AbstractRenderer {
 
     private String linkPrefix;
     private String linePrefix;
@@ -25,31 +27,30 @@ public class HTMLRenderer extends AbstractRenderer implements Renderer {
         this(null, null);
     }
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
-        StringBuffer buf = new StringBuffer("<html><head><title>PMD</title></head><body>" + PMD.EOL);
+        writer.write("<html><head><title>PMD</title></head><body>" + PMD.EOL);
-        buf.append(renderBody(report));
+        renderBody(writer, report);
-        buf.append("</body></html>");
+        writer.write("</body></html>");
-        return buf.toString();
     }
 
-    public String renderBody(Report report) {
+    public void renderBody(Writer writer, Report report) throws IOException {
-        StringBuffer buf = glomIRuleViolations(report);
+        glomIRuleViolations(writer, report);
-        glomProcessingErrors(report, buf);
+        glomProcessingErrors(writer, report);
         if (showSuppressedViolations) {
-            glomSuppressions(report, buf);
+            glomSuppressions(writer, report);
         }
-        return buf.toString();
     }
     
-    private StringBuffer glomIRuleViolations(Report report) {
+    private void glomIRuleViolations(Writer writer, Report report) throws IOException {
         boolean colorize = true;
         int violationCount = 1;
         StringBuffer buf = new StringBuffer(500);
-        buf.append("<center><h3>PMD report</h3></center>");
+        writer.write("<center><h3>PMD report</h3></center>");
-        buf.append("<center><h3>Problems found</h3></center>");
+        writer.write("<center><h3>Problems found</h3></center>");
-        buf.append("<table align=\"center\" cellspacing=\"0\" cellpadding=\"3\"><tr>" + PMD.EOL + "<th>#</th><th>File</th><th>Line</th><th>Problem</th></tr>" + PMD.EOL);
+        writer.write("<table align=\"center\" cellspacing=\"0\" cellpadding=\"3\"><tr>" + PMD.EOL + "<th>#</th><th>File</th><th>Line</th><th>Problem</th></tr>" + PMD.EOL);
         for (Iterator i = report.iterator(); i.hasNext();) {
             IRuleViolation rv = (IRuleViolation) i.next();
+            buf.setLength(0);
             buf.append("<tr");
             if (colorize) {
                 buf.append(" bgcolor=\"lightgrey\"");
@@ -67,26 +68,28 @@ public class HTMLRenderer extends AbstractRenderer implements Renderer {
             }
             buf.append("<td width=\"*\">" + d + "</td>" + PMD.EOL);
             buf.append("</tr>" + PMD.EOL);
+            writer.write(buf.toString());
             violationCount++;
         }
         if (violationCount > 0) {
-            buf.append("</table>");
+            writer.write("</table>");
         }
-        return buf;
     }
 
-    private void glomProcessingErrors(Report report, StringBuffer buf) {
+    private void glomProcessingErrors(Writer writer, Report report) throws IOException {
         boolean colorize = true;
         int violationCount;
         // errors
         if (report.errors().hasNext()) {
-            buf.append("<hr/>");
+            writer.write("<hr/>");
-            buf.append("<center><h3>Processing errors</h3></center>");
+            writer.write("<center><h3>Processing errors</h3></center>");
-            buf.append("<table align=\"center\" cellspacing=\"0\" cellpadding=\"3\"><tr>" + PMD.EOL + "<th>File</th><th>Problem</th></tr>" + PMD.EOL);
+            writer.write("<table align=\"center\" cellspacing=\"0\" cellpadding=\"3\"><tr>" + PMD.EOL + "<th>File</th><th>Problem</th></tr>" + PMD.EOL);
         }
         violationCount = 0;
+        StringBuffer buf = new StringBuffer(500);
         for (Iterator i = report.errors(); i.hasNext();) {
             Report.ProcessingError pe = (Report.ProcessingError) i.next();
+            buf.setLength(0);
             buf.append("<tr");
             if (colorize) {
                 buf.append(" bgcolor=\"lightgrey\"");
@@ -96,24 +99,27 @@ public class HTMLRenderer extends AbstractRenderer implements Renderer {
             buf.append("<td>" + pe.getFile() + "</td>" + PMD.EOL);
             buf.append("<td>" + pe.getMsg() + "</td>" + PMD.EOL);
             buf.append("</tr>" + PMD.EOL);
+            writer.write(buf.toString());
             violationCount++;
         }
         if (violationCount > 0) {
-            buf.append("</table>");
+            writer.write("</table>");
         }
     }
 
-    private void glomSuppressions(Report report, StringBuffer buf) {
+    private void glomSuppressions(Writer writer, Report report) throws IOException {
         boolean colorize = true;
         boolean hasSuppressedViolations = !report.getSuppressedRuleViolations().isEmpty();
         if (hasSuppressedViolations) {
-            buf.append("<hr/>");
+            writer.write("<hr/>");
-            buf.append("<center><h3>Suppressed warnings</h3></center>");
+            writer.write("<center><h3>Suppressed warnings</h3></center>");
-            buf.append("<table align=\"center\" cellspacing=\"0\" cellpadding=\"3\"><tr>" + PMD.EOL + "<th>File</th><th>Line</th><th>Rule</th><th>NOPMD or Annotation</th><th>Reason</th></tr>" + PMD.EOL);
+            writer.write("<table align=\"center\" cellspacing=\"0\" cellpadding=\"3\"><tr>" + PMD.EOL + "<th>File</th><th>Line</th><th>Rule</th><th>NOPMD or Annotation</th><th>Reason</th></tr>" + PMD.EOL);
         }
         Report.SuppressedViolation sv;
+        StringBuffer buf = new StringBuffer(500);
         for (Iterator i = report.getSuppressedRuleViolations().iterator(); i.hasNext();) {
             sv = (Report.SuppressedViolation) i.next();
+            buf.setLength(0);
             buf.append("<tr");
             if (colorize) {
                 buf.append(" bgcolor=\"lightgrey\"");
@@ -126,9 +132,10 @@ public class HTMLRenderer extends AbstractRenderer implements Renderer {
             buf.append("<td align=\"center\">" + (sv.suppressedByNOPMD() ? "NOPMD" : "Annotation") + "</td>" + PMD.EOL);
             buf.append("<td align=\"center\">" + (sv.getUserMessage() == null ? "" : sv.getUserMessage()) + "</td>" + PMD.EOL);
             buf.append("</tr>" + PMD.EOL);
+            writer.write(buf.toString());
         }
         if (hasSuppressedViolations) {
-            buf.append("</table>");
+            writer.write("</table>");
         }
     }
 

pmd/src/net/sourceforge/pmd/renderers/IDEAJRenderer.java

@@ -7,12 +7,14 @@ import net.sourceforge.pmd.IRuleViolation;
 import net.sourceforge.pmd.PMD;
 import net.sourceforge.pmd.Report;
 
+import java.io.IOException;
+import java.io.Writer;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Set;
 import java.util.StringTokenizer;
 
-public class IDEAJRenderer extends AbstractRenderer implements Renderer {
+public class IDEAJRenderer extends AbstractRenderer {
 
 	private static final String FILE_SEPARATOR = System.getProperty("file.separator");
 	private static final String PATH_SEPARATOR = System.getProperty("path.separator");
@@ -44,38 +46,41 @@ public class IDEAJRenderer extends AbstractRenderer implements Renderer {
         this.args = args;
     }
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
         if (args[4].equals(".method")) {
             // working on a directory tree
             String sourcePath = args[3];
-            return render(report, sourcePath);
+            render(writer, report, sourcePath);
+            return;
         }
         // working on one file
         String classAndMethodName = args[4];
         String singleFileName = args[5];
-        return render(report, classAndMethodName, singleFileName);
+        render(writer, report, classAndMethodName, singleFileName);
     }
 
-    private String render(Report report, String sourcePathString) {
+    private void render(Writer writer, Report report, String sourcePathString) throws IOException {
         SourcePath sourcePath = new SourcePath(sourcePathString);
         StringBuffer buf = new StringBuffer();
         for (Iterator i = report.iterator(); i.hasNext();) {
+            buf.setLength(0);
             IRuleViolation rv = (IRuleViolation) i.next();
             buf.append(rv.getDescription() + PMD.EOL);
             buf.append(" at ").append(getFullyQualifiedClassName(rv.getFilename(), sourcePath)).append(".method(");
             buf.append(getSimpleFileName(rv.getFilename())).append(':').append(rv.getBeginLine()).append(')').append(PMD.EOL);
+            writer.write(buf.toString());
         }
-        return buf.toString();
     }
 
-    private String render(Report report, String classAndMethod, String file) {
+    private void render(Writer writer, Report report, String classAndMethod, String file) throws IOException {
         StringBuffer buf = new StringBuffer();
         for (Iterator i = report.iterator(); i.hasNext();) {
+            buf.setLength(0);
             IRuleViolation rv = (IRuleViolation) i.next();
             buf.append(rv.getDescription()).append(PMD.EOL);
             buf.append(" at ").append(classAndMethod).append('(').append(file).append(':').append(rv.getBeginLine()).append(')').append(PMD.EOL);
+            writer.write(buf.toString());
         }
-        return buf.toString();
     }
 
     private String getFullyQualifiedClassName(String in, SourcePath sourcePath) {

pmd/src/net/sourceforge/pmd/renderers/PapariTextRenderer.java

@@ -11,6 +11,7 @@ import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
+import java.io.Writer;
 import java.util.Iterator;
 import java.util.Map;
 
@@ -44,7 +45,7 @@ import java.util.Map;
  * colorization is atm only supported under *nix terminals accepting ansi escape
  * sequences, such as xterm, rxvt et cetera.</p>
  */
-public class PapariTextRenderer extends AbstractRenderer implements Renderer {
+public class PapariTextRenderer extends AbstractRenderer {
     /**
      * Directory from where java was invoked.
      */
@@ -78,7 +79,7 @@ public class PapariTextRenderer extends AbstractRenderer implements Renderer {
         }
     }
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
         StringBuffer buf = new StringBuffer(PMD.EOL);
         initializeColorsIfSupported();
         String lastFile = null;
@@ -86,6 +87,7 @@ public class PapariTextRenderer extends AbstractRenderer implements Renderer {
         int numberOfWarnings = 0;
 
         for (Iterator i = report.iterator(); i.hasNext();) {
+            buf.setLength(0);
             numberOfWarnings++;
             IRuleViolation rv = (IRuleViolation) i.next();
             if (!rv.getFilename().equals(lastFile)) {
@@ -96,17 +98,21 @@ public class PapariTextRenderer extends AbstractRenderer implements Renderer {
             buf.append(this.green + "    rule: " + this.colorReset + rv.getRule().getName() + PMD.EOL);
             buf.append(this.green + "    msg:  " + this.colorReset + rv.getDescription() + PMD.EOL);
             buf.append(this.green + "    code: " + this.colorReset + this.getLine(lastFile, rv.getBeginLine()) + PMD.EOL + PMD.EOL);
+            writer.write(buf.toString());
         }
-        buf.append(PMD.EOL + PMD.EOL);
+        writer.write(PMD.EOL + PMD.EOL);
-        buf.append("Summary:" + PMD.EOL + PMD.EOL);
+        writer.write("Summary:" + PMD.EOL + PMD.EOL);
         Map summary = report.getCountSummary();
         for (Iterator i = summary.entrySet().iterator(); i.hasNext();) {
+            buf.setLength(0);
             Map.Entry entry = (Map.Entry) i.next();
             String key = (String) entry.getKey();
             buf.append(key + " : " + ((Integer) entry.getValue()).intValue() + PMD.EOL);
+            writer.write(buf.toString());
         }
 
         for (Iterator i = report.errors(); i.hasNext();) {
+            buf.setLength(0);
             numberOfErrors++;
             Report.ProcessingError error = (Report.ProcessingError) i.next();
             if (error.getFile().equals(lastFile)) {
@@ -114,15 +120,14 @@ public class PapariTextRenderer extends AbstractRenderer implements Renderer {
                 buf.append(this.redBold + "*" + this.colorReset + " file: " + this.whiteBold + this.getRelativePath(lastFile) + this.colorReset + PMD.EOL);
             }
             buf.append(this.green + "    err:  " + this.cyan + error.getMsg() + this.colorReset + PMD.EOL + PMD.EOL);
+            writer.write(buf.toString());
         }
 
         // adding error message count, if any
         if (numberOfErrors > 0) {
-            buf.append(this.redBold + "*" + this.colorReset + " errors:   " + this.whiteBold + numberOfWarnings + this.colorReset + PMD.EOL);
+            writer.write(this.redBold + "*" + this.colorReset + " errors:   " + this.whiteBold + numberOfWarnings + this.colorReset + PMD.EOL);
         }
-        buf.append(this.yellowBold + "*" + this.colorReset + " warnings: " + this.whiteBold + numberOfWarnings + this.colorReset + PMD.EOL);
+        writer.write(this.yellowBold + "*" + this.colorReset + " warnings: " + this.whiteBold + numberOfWarnings + this.colorReset + PMD.EOL);
-
-        return buf.toString();
     }
 
     /**

pmd/src/net/sourceforge/pmd/renderers/Renderer.java

@@ -3,10 +3,23 @@
  */
 package net.sourceforge.pmd.renderers;
 
+import java.io.IOException;
+import java.io.Writer;
+
 import net.sourceforge.pmd.Report;
 
 public interface Renderer {
+
     void showSuppressedViolations(boolean show);
 
+    /**
+     * 
+     * @deprecated This method consumes too much memory.
+     * Use the render method with the Writer argument instead.
+     * 
+     */
     String render(Report report);
+
+    void render(Writer writer, Report report) throws IOException;
+
 }

pmd/src/net/sourceforge/pmd/renderers/SummaryHTMLRenderer.java

@@ -3,10 +3,12 @@ package net.sourceforge.pmd.renderers;
 import net.sourceforge.pmd.PMD;
 import net.sourceforge.pmd.Report;
 
+import java.io.IOException;
+import java.io.Writer;
 import java.util.Iterator;
 import java.util.Map;
 
-public class SummaryHTMLRenderer extends AbstractRenderer implements Renderer {
+public class SummaryHTMLRenderer extends AbstractRenderer {
     private String linePrefix,linkPrefix;
     public SummaryHTMLRenderer(String linkPrefix, String linePrefix) {
         this.linePrefix = linePrefix;
@@ -17,32 +19,33 @@ public class SummaryHTMLRenderer extends AbstractRenderer implements Renderer {
         this(null,null);
     }
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
-        StringBuffer buf = new StringBuffer("<html><head><title>PMD</title></head><body>" + PMD.EOL);
+        writer.write("<html><head><title>PMD</title></head><body>" + PMD.EOL);
-        buf.append(renderSummary(report));
+        renderSummary(writer, report);
-        buf.append("<h2><center>Detail</h2></center>");
+        writer.write("<h2><center>Detail</h2></center>");
-        buf.append("<table align=\"center\" cellspacing=\"0\" cellpadding=\"3\"><tr>" + PMD.EOL + "<th>#</th><th>File</th><th>Line</th><th>Problem</th></tr>" + PMD.EOL);
+        writer.write("<table align=\"center\" cellspacing=\"0\" cellpadding=\"3\"><tr>" + PMD.EOL + "<th>#</th><th>File</th><th>Line</th><th>Problem</th></tr>" + PMD.EOL);
-        buf.append(new HTMLRenderer(linkPrefix,linePrefix).renderBody(report));
+        new HTMLRenderer(linkPrefix,linePrefix).renderBody(writer, report);
-        buf.append("</table></body></html>");
+        writer.write("</table></body></html>");
-        return buf.toString();
     }
 
-    public String renderSummary(Report report) {
+    public void renderSummary(Writer writer, Report report) throws IOException {
         StringBuffer buf = new StringBuffer();
         buf.append("<h2><center>Summary</h2></center>");
         buf.append("<table align=\"center\" cellspacing=\"0\" cellpadding=\"3\">");
         buf.append("<th>Rule name</th>");
         buf.append("<th>Number of violations</th>");
+        writer.write(buf.toString());
         Map summary = report.getSummary();
         for (Iterator i = summary.entrySet().iterator(); i.hasNext();) {
             Map.Entry entry = (Map.Entry) i.next();
             String ruleName = (String) entry.getKey();
+            buf.setLength(0);
             buf.append("<tr>");
             buf.append("<td>" + ruleName + "</td>");
             buf.append("<td align=center>" + ((Integer) entry.getValue()).intValue() + "</td>");
             buf.append("</tr>");
+            writer.write(buf.toString());
         }
-        buf.append("</table>");
+        writer.write("</table>");
-        return buf.toString();
     }
 }

pmd/src/net/sourceforge/pmd/renderers/TextPadRenderer.java

@@ -7,6 +7,8 @@ import net.sourceforge.pmd.IRuleViolation;
 import net.sourceforge.pmd.PMD;
 import net.sourceforge.pmd.Report;
 
+import java.io.IOException;
+import java.io.Writer;
 import java.util.Iterator;
 
 /**
@@ -24,8 +26,8 @@ import java.util.Iterator;
  *
  * @author Jeff Epstein, based upon <a href="EmacsRenderer.html">EmacsRenderer</a>, Tuesday, September 23, 2003
  */
-public class TextPadRenderer extends AbstractRenderer implements Renderer {
+public class TextPadRenderer extends AbstractRenderer {
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
         StringBuffer buf = new StringBuffer();
         Iterator i;
         try {
@@ -35,6 +37,7 @@ public class TextPadRenderer extends AbstractRenderer implements Renderer {
         }
         while (i.hasNext()) {
             IRuleViolation rv = (IRuleViolation) i.next();
+            buf.setLength(0);
             //Filename
             buf.append(PMD.EOL).append(rv.getFilename() + "(");
             //Line number
@@ -43,7 +46,7 @@ public class TextPadRenderer extends AbstractRenderer implements Renderer {
             buf.append(rv.getRule().getName()).append("):  ");
             //Specific violation message
             buf.append(rv.getDescription());
+            writer.write(buf.toString());
         }
-        return buf.toString();
     }
 }

pmd/src/net/sourceforge/pmd/renderers/TextRenderer.java

@@ -7,11 +7,13 @@ import net.sourceforge.pmd.IRuleViolation;
 import net.sourceforge.pmd.PMD;
 import net.sourceforge.pmd.Report;
 
+import java.io.IOException;
+import java.io.Writer;
 import java.util.Iterator;
 
-public class TextRenderer extends AbstractRenderer implements Renderer {
+public class TextRenderer extends AbstractRenderer {
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
         StringBuffer buf = new StringBuffer();
 
         if (report.isEmpty()) {
@@ -19,28 +21,33 @@ public class TextRenderer extends AbstractRenderer implements Renderer {
             if (showSuppressedViolations) {
                 addSuppressed(report, buf);
             }
-            return buf.toString();
+            writer.write(buf.toString());
+            return;
         }
         Iterator i;
         
         for (i = report.iterator(); i.hasNext();) {
+            buf.setLength(0);
             IRuleViolation rv = (IRuleViolation) i.next();
             buf.append(PMD.EOL).append(rv.getFilename());
             buf.append(':').append(Integer.toString(rv.getBeginLine()));
             buf.append('\t').append(rv.getDescription());
+            writer.write(buf.toString());
         }
 
         for (i = report.errors(); i.hasNext();) {
+            buf.setLength(0);
             Report.ProcessingError error = (Report.ProcessingError) i.next();
             buf.append(PMD.EOL).append(error.getFile());
             buf.append("\t-\t").append(error.getMsg());
+            writer.write(buf.toString());
         }
 
         if (showSuppressedViolations) {
+            buf.setLength(0);
             addSuppressed(report, buf);
+            writer.write(buf.toString());
         }
-
-        return buf.toString();
     }
 
     private void addSuppressed(Report report, StringBuffer buf) {

pmd/src/net/sourceforge/pmd/renderers/VBHTMLRenderer.java

@@ -7,17 +7,19 @@ import net.sourceforge.pmd.IRuleViolation;
 import net.sourceforge.pmd.PMD;
 import net.sourceforge.pmd.Report;
 
+import java.io.IOException;
+import java.io.Writer;
 import java.util.Iterator;
 
 /**
  * @author Vladimir
  * @version $Revision$ $Date$
  */
-public class VBHTMLRenderer extends AbstractRenderer implements Renderer {
+public class VBHTMLRenderer extends AbstractRenderer {
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
         if (report.isEmpty()) {
-            return "";
+            return;
         }
 
         StringBuffer sb = new StringBuffer(header());
@@ -27,6 +29,7 @@ public class VBHTMLRenderer extends AbstractRenderer implements Renderer {
         boolean colorize = false;
 
         for (Iterator iter = report.iterator(); iter.hasNext();) {
+            sb.setLength(0);
             IRuleViolation rv = (IRuleViolation) iter.next();
             if (!rv.getFilename().equals(filename)) { // New File
                 if (filename != null) {
@@ -50,15 +53,17 @@ public class VBHTMLRenderer extends AbstractRenderer implements Renderer {
             sb.append("<td><font class=body>" + rv.getDescription() + "</font></td>");
             sb.append("</tr>");
             sb.append(lineSep);
+            writer.write(sb.toString());
         }
         if (filename != null) {
-            sb.append("</table>");
+            writer.write("</table>");
         }
-        sb.append("<br>");
+        writer.write("<br>");
 
         // output the problems
         Iterator iter = report.errors();
         if (iter.hasNext()) {
+            sb.setLength(0);
             sb.append("<table border=\"0\" width=\"80%\">");
             sb.append("<tr id=TableHeader><td><font class=title>&nbsp;Problems found</font></td></tr>");
             colorize = false;
@@ -72,11 +77,10 @@ public class VBHTMLRenderer extends AbstractRenderer implements Renderer {
                 sb.append("<td><font class=body>").append(iter.next()).append("\"</font></td></tr>");
             }
             sb.append("</table>");
+            writer.write(sb.toString());
         }
 
-        sb.append(footer());
+        writer.write(footer());
-
-        return sb.toString();
     }
 
     private String header() {

pmd/src/net/sourceforge/pmd/renderers/XMLRenderer.java

@@ -8,19 +8,23 @@ import net.sourceforge.pmd.PMD;
 import net.sourceforge.pmd.Report;
 import net.sourceforge.pmd.util.StringUtil;
 
+import java.io.IOException;
+import java.io.Writer;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.Iterator;
 
-public class XMLRenderer extends AbstractRenderer implements Renderer {
+public class XMLRenderer extends AbstractRenderer {
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
 
-        StringBuffer buf = new StringBuffer("<?xml version=\"1.0\" encoding=\"UTF-8\"?>" + PMD.EOL + createVersionAttr() + createTimestampAttr() + createTimeElapsedAttr(report) + '>' + PMD.EOL);
+        StringBuffer buf = new StringBuffer();
+        writer.write("<?xml version=\"1.0\" encoding=\"UTF-8\"?>" + PMD.EOL + createVersionAttr() + createTimestampAttr() + createTimeElapsedAttr(report) + '>' + PMD.EOL);
         String filename = null;
 
         // rule violations
         for (Iterator i = report.iterator(); i.hasNext();) {
+            buf.setLength(0);
             IRuleViolation rv = (IRuleViolation) i.next();
             if (!rv.getFilename().equals(filename)) { // New File
                 if (filename != null) {// Not first file ?
@@ -50,24 +54,29 @@ public class XMLRenderer extends AbstractRenderer implements Renderer {
             buf.append(PMD.EOL);
             buf.append("</violation>");
             buf.append(PMD.EOL);
+            writer.write(buf.toString());
         }
         if (filename != null) { // Not first file ?
-            buf.append("</file>").append(PMD.EOL);
+            writer.write("</file>");
+            writer.write(PMD.EOL);
         }
 
         // errors
         for (Iterator i = report.errors(); i.hasNext();) {
+            buf.setLength(0);
             Report.ProcessingError pe = (Report.ProcessingError) i.next();
             buf.append("<error ").append("filename=\"");
             StringUtil.appendXmlEscaped(buf, pe.getFile());
             buf.append("\" msg=\"");
             StringUtil.appendXmlEscaped(buf, pe.getMsg());
             buf.append("\"/>").append(PMD.EOL);
+            writer.write(buf.toString());
         }
 
         // suppressed violations
         if (showSuppressedViolations) {
             for (Iterator i = report.getSuppressedRuleViolations().iterator(); i.hasNext();) {
+                buf.setLength(0);
                 Report.SuppressedViolation suppressed = (Report.SuppressedViolation) i.next();
                 buf.append("<suppressedviolation ").append("filename=\"");
                 StringUtil.appendXmlEscaped(buf, suppressed.getRuleViolation().getFilename());
@@ -78,11 +87,11 @@ public class XMLRenderer extends AbstractRenderer implements Renderer {
                 buf.append("\" usermsg=\"");
                 StringUtil.appendXmlEscaped(buf, suppressed.getUserMessage());
                 buf.append("\"/>").append(PMD.EOL);
+                writer.write(buf.toString());
             }
         }
 
-        buf.append("</pmd>");
+        writer.write("</pmd>");
-        return buf.toString();
     }
 
     private void maybeAdd(String attr, String value, StringBuffer buf) {

pmd/src/net/sourceforge/pmd/renderers/YAHTMLRenderer.java

@@ -1,15 +1,18 @@
 package net.sourceforge.pmd.renderers;
 
+import java.io.IOException;
+import java.io.Writer;
+
 import net.sourceforge.pmd.Report;
 import net.sourceforge.pmd.dfa.report.ReportHTMLPrintVisitor;
 import net.sourceforge.pmd.dfa.report.ReportTree;
 
-public class YAHTMLRenderer extends AbstractRenderer implements Renderer {
+public class YAHTMLRenderer extends AbstractRenderer {
 
-    public String render(Report report) {
+    public void render(Writer writer, Report report) throws IOException {
         ReportTree tree = report.getViolationTree();
         tree.getRootNode().accept(new ReportHTMLPrintVisitor());
-        return "<h3 align=\"center\">The HTML files are created above the project directory.</h3>";
+        writer.write("<h3 align=\"center\">The HTML files are created above the project directory.</h3>");
     }
 
 }