How to download a file from webpage using Htmlunit having javascript in anchor tag -

i trying click on link download file :

http://www.histdata.com/download-free-forex-historical-data/?/metatrader/1-minute-bar-quotes/eurusd/2013

the html code line trying download is:

<a id="a_file" title="download zip data file"      href="javascript:return true;" target="nulldisplay">histdata_com_mt_eurusd_m1_2013.zip</a> 

and java code is:

webclient webclient = new webclient(browserversion.firefox_38); webclient.getoptions().setjavascriptenabled(true);   webclient.setajaxcontroller(new nicelyresynchronizingajaxcontroller()); htmlpage htmlpage=webclient.getpage("http://www.histdata.com/download-free-forex-historical-data/?/metatrader/1-minute-bar-quotes/eurusd/2016/7"); list<htmlanchor> anchors=htmlpage.getanchors(); htmlanchor anchor = null; (int = 0; < anchors.size(); ++i) {     anchor = anchors.get(i);     string sanchor = anchor.astext();      if (sanchor.equals("histdata_com_mt_eurusd_m1_201607.zip"))         break; } page p = anchor.click();  webclient.waitforbackgroundjavascript(60000); inputstream = p.getwebresponse().getcontentasstream(); int b = 0; while ((b = is.read()) != -1) {     system.out.print((char)b); } 

the error message is:

jul 12, 2016 1:29:57 pm com.gargoylesoftware.htmlunit.javascript.stricterrorreporter error severe: error: message=[invalid return] sourcename=[javascript url] line=[88] linesource=[return true;] lineoffset=[7] exception in thread "main" ======= exception start ======== exception class=[net.sourceforge.htmlunit.corejs.javascript.evaluatorexception] com.gargoylesoftware.htmlunit.scriptexception: invalid return (javascript url#88)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine$htmlunitcontextaction.run(javascriptengine.java:904)     @ net.sourceforge.htmlunit.corejs.javascript.context.call(context.java:628)     @ net.sourceforge.htmlunit.corejs.javascript.contextfactory.call(contextfactory.java:515)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine.compile(javascriptengine.java:729)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine.compile(javascriptengine.java:694)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine.execute(javascriptengine.java:746)     @ com.gargoylesoftware.htmlunit.html.htmlpage.executejavascriptifpossible(htmlpage.java:902)     @ com.gargoylesoftware.htmlunit.html.htmlanchor.doclickstateupdate(htmlanchor.java:114)     @ com.gargoylesoftware.htmlunit.html.htmlanchor.doclickstateupdate(htmlanchor.java:179)     @ com.gargoylesoftware.htmlunit.html.domelement.click(domelement.java:800)     @ com.gargoylesoftware.htmlunit.html.domelement.click(domelement.java:747)     @ com.gargoylesoftware.htmlunit.html.domelement.click(domelement.java:694)     @ clickpage.main(clickpage.java:38) caused by: net.sourceforge.htmlunit.corejs.javascript.evaluatorexception: invalid return (javascript url#88)     @ com.gargoylesoftware.htmlunit.javascript.stricterrorreporter.error(stricterrorreporter.java:65)     @ net.sourceforge.htmlunit.corejs.javascript.parser.adderror(parser.java:188)     @ net.sourceforge.htmlunit.corejs.javascript.parser.adderror(parser.java:167)     @ net.sourceforge.htmlunit.corejs.javascript.parser.reporterror(parser.java:255)     @ net.sourceforge.htmlunit.corejs.javascript.parser.reporterror(parser.java:244)     @ net.sourceforge.htmlunit.corejs.javascript.parser.reporterror(parser.java:237)     @ net.sourceforge.htmlunit.corejs.javascript.parser.returnoryield(parser.java:1632)     @ net.sourceforge.htmlunit.corejs.javascript.parser.statementhelper(parser.java:1022)     @ net.sourceforge.htmlunit.corejs.javascript.parser.statement(parser.java:928)     @ net.sourceforge.htmlunit.corejs.javascript.parser.parse(parser.java:572)     @ net.sourceforge.htmlunit.corejs.javascript.parser.parse(parser.java:492)     @ net.sourceforge.htmlunit.corejs.javascript.context.compileimpl(context.java:2660)     @ net.sourceforge.htmlunit.corejs.javascript.context.compilestring(context.java:1623)     @ com.gargoylesoftware.htmlunit.javascript.htmlunitcontextfactory$timeoutcontext.compilestring(htmlunitcontextfactory.java:172)     @ net.sourceforge.htmlunit.corejs.javascript.context.compilestring(context.java:1615)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine$2.dorun(javascriptengine.java:720)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine$htmlunitcontextaction.run(javascriptengine.java:889)     ... 12 more enclosed exception:  net.sourceforge.htmlunit.corejs.javascript.evaluatorexception: invalid return (javascript url#88)     @ com.gargoylesoftware.htmlunit.javascript.stricterrorreporter.error(stricterrorreporter.java:65)     @ net.sourceforge.htmlunit.corejs.javascript.parser.adderror(parser.java:188)     @ net.sourceforge.htmlunit.corejs.javascript.parser.adderror(parser.java:167)     @ net.sourceforge.htmlunit.corejs.javascript.parser.reporterror(parser.java:255)     @ net.sourceforge.htmlunit.corejs.javascript.parser.reporterror(parser.java:244)     @ net.sourceforge.htmlunit.corejs.javascript.parser.reporterror(parser.java:237)     @ net.sourceforge.htmlunit.corejs.javascript.parser.returnoryield(parser.java:1632)     @ net.sourceforge.htmlunit.corejs.javascript.parser.statementhelper(parser.java:1022)     @ net.sourceforge.htmlunit.corejs.javascript.parser.statement(parser.java:928)     @ net.sourceforge.htmlunit.corejs.javascript.parser.parse(parser.java:572)     @ net.sourceforge.htmlunit.corejs.javascript.parser.parse(parser.java:492)     @ net.sourceforge.htmlunit.corejs.javascript.context.compileimpl(context.java:2660)     @ net.sourceforge.htmlunit.corejs.javascript.context.compilestring(context.java:1623)     @ com.gargoylesoftware.htmlunit.javascript.htmlunitcontextfactory$timeoutcontext.compilestring(htmlunitcontextfactory.java:172)     @ net.sourceforge.htmlunit.corejs.javascript.context.compilestring(context.java:1615)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine$2.dorun(javascriptengine.java:720)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine$htmlunitcontextaction.run(javascriptengine.java:889)     @ net.sourceforge.htmlunit.corejs.javascript.context.call(context.java:628)     @ net.sourceforge.htmlunit.corejs.javascript.contextfactory.call(contextfactory.java:515)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine.compile(javascriptengine.java:729)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine.compile(javascriptengine.java:694)     @ com.gargoylesoftware.htmlunit.javascript.javascriptengine.execute(javascriptengine.java:746)     @ com.gargoylesoftware.htmlunit.html.htmlpage.executejavascriptifpossible(htmlpage.java:902)     @ com.gargoylesoftware.htmlunit.html.htmlanchor.doclickstateupdate(htmlanchor.java:114)     @ com.gargoylesoftware.htmlunit.html.htmlanchor.doclickstateupdate(htmlanchor.java:179)     @ com.gargoylesoftware.htmlunit.html.domelement.click(domelement.java:800)     @ com.gargoylesoftware.htmlunit.html.domelement.click(domelement.java:747)     @ com.gargoylesoftware.htmlunit.html.domelement.click(domelement.java:694)     @ clickpage.main(clickpage.java:38) == calling javascript == return true; ======= exception end ======== 

please let me know wrong in code , how download file given link.

//complete solution  //1. open page  //2. list urls of page using xpath //3. download file of url .  import java.io.file; import java.io.fileoutputstream; import java.io.ioexception; import java.io.inputstream; import java.io.outputstream; import java.net.httpurlconnection; import java.net.url; import java.util.date; import java.util.list; import java.util.map;  import com.gargoylesoftware.htmlunit.browserversion; import com.gargoylesoftware.htmlunit.webclient; import com.gargoylesoftware.htmlunit.html.domattr; import com.gargoylesoftware.htmlunit.html.htmlanchor; import com.gargoylesoftware.htmlunit.html.htmlpage;  public class crawler {      public static void main(string[] args) throws throwable {          string baseurl= "enter base http/https url here";         string url1 = baseurl+ "add addational url of main page";         string xpathofdownlaodlinks = "xpath of file url or--> html/body/div/div[3]/a/@href";          string pathtosavefile="d:\\local\\to\\save\\files";          string fileext = ".txt";          webclient webclient = new webclient(browserversion.chrome);         webclient.getoptions().setjavascriptenabled(true);         htmlpage page = webclient.getpage(url1);          list<domattr> links = (list<domattr>) page.getbyxpath(xpathofdownlaodlinks);          list<htmlanchor> anchors=page.getanchors();          (domattr object : links) {             string link = baseurl+object.getvalue()+"";              date d=new date();              downlaodrawfile(link,pathtosavefile +d.gettime() + fileext);         }             webclient.close();     }      public static void downlaodrawfile(string link,string filename) throws ioexception, throwable{               url               url  = new url( link );               httpurlconnection http = (httpurlconnection)url.openconnection();               map< string, list< string >> header = http.getheaderfields();               while( isredirected( header )) {                  link = header.get( "location" ).get( 0 );                  url    = new url( link );                  http   = (httpurlconnection)url.openconnection();                  header = http.getheaderfields();               }               inputstream  input  = http.getinputstream();               byte[]       buffer = new byte[4096];               int          n      = -1;               outputstream output = new fileoutputstream( new file( filename ));               while ((n = input.read(buffer)) != -1) {                  output.write( buffer, 0, n );               }               output.close();     }      private static boolean isredirected( map<string, list<string>> header ) {           for( string hv : header.get( null )) {              if(   hv.contains( " 301 " )                 || hv.contains( " 302 " )) return true;           }           return false;        }  }