title: Tracking down a NullPointerException
body: <p>I need to save data to MySQL database. Problem is that I have a lot of new data every second and need to filter it so I would save only necessary data. So, when I get new data, I create an object and call method processData. For some reason, this is not working. This is my method:</p>
  
  <pre><code>import java.util.Date;
  import org.llrp.ltk.types.UnsignedShort;
  import hr.fer.rfid.MySQLAccess;
  public class Brain {
      Data[] datas = new Data[]();
      Data[] temps = new Data[]();
      public void processValues(Data dat){
  
         if(temps==null){
             datas[0]=dat;
             temps[0]=dat;
         }
         for (i=0;i&lt;(temps.length+1);i++){
            System.out.println("Process value: "+i);
            if(i==(temps.length+1)){
               temps[i]=dat;
               datas[datas.length+1]=dat;
            }
            if(i&lt;=temps.length) {
             if(dat.epc==temps[i].epc)
                if((dat.antenna!=temps[i].antenna)
                  ||((dat.date.getTime()-temps[i].date.getTime()&gt;=5000)
                    &amp;&amp;(dat.date.getTime()-temps[i].date.getTime()&lt;=20000))) {
                    temps[i]=dat;
                    try {
  
                     dao.writeToDatabase(dat);
                    } catch (Exception e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                    }
                }
            }
         }
      }
   }
  </code></pre>
  
  <p>I get <code>NullPointerException</code></p>