title: How to recovery this error: log4j:WARN No appenders could be found for logger (net.sf.jasperreports.extensions.ExtensionsEnvironment)
body: <p>I try to make report with ireport but i get this problem:</p>
  
  <pre>log4j:WARN No appenders could be found for logger(net.sf.jasperreports.extensions.ExtensionsEnvironment).
  log4j:WARN Please initialize the log4j system properly.</pre>
  
  <p>My source:</p>
  
  <pre><code>private URL[] reports = new URL[]{
          getClass().getResource("/Laporan/LapGuru.Jasper"),
          getClass().getResource("/Laporan/LapGuruByNIP.Jasper"),};
          private URL urlCurrent;
  
      try{           
  
              Map parameter = new HashMap();
  
              parameter.put("nip",this.txtNIP.getText());
              InputStream os = null;
              os = urlCurrent.openStream();
              JasperReport jReport = (JasperReport)JRLoader.loadObject(os);
              JasperPrint jPrint = JasperFillManager.fillReport(jReport, parameter, ClassDB.getkoneksi());
              JRViewer viewer = new JRViewer(jPrint);
              viewer.setOpaque(true);
              viewer.setVisible(true);
              jScrollPane1.add(viewer);
              jScrollPane1.setViewportView(viewer);
  
              } catch (Exception ex)
              {
                  System.out.println(ex);
              }
  </code></pre>