Java Constructor never finish constructing -

i not @ oop, got problem constructor not returning anything.

public class crossentropy extends thread{      protected cemobileagentmigrationplan appowner;     private sensornode[] sensornodes;     private jlabel status;     private jtextarea textarea;     integer temp = null;     boolean first=true;     int tempor;     int populasi=1000;     double = 0.8;     double g=(int)(populasi/3);     int max=appowner.sensorcount+populasi;     private double costa=0;     private int[] samatidak;     public int[] mem;     private double[] sortbox;         private double w[][]  = new double[max][max];     private double p[][]  = new double[max][max];     private double[][] pn;     private int[][] jalur;     private double[] cost;     boolean first2;      public crossentropy(cemobileagentmigrationplan appowner){         system.out.println("hi !");         this.appowner=appowner;         system.out.println("hi hi hello !");         this.sensornodes=appowner.sensornodelist;         system.out.println("hello !");     }      //method shortened      public void run(){//engga kepanggil         system.out.println("testtament");         double time = system.currenttimemillis();         double thiscost = 0.0;         double oldcost = 0.0;         int countsame=0;         int duration=0;         double hasilakhir =0;         boolean cek = false;         //matrikrate();         while (countsame<1000){             membangkitkantour();             getcost();             thiscost = costa;             if (cek==false){                oldcost=thiscost;                cek=true;             }             if (thiscost<oldcost){                  oldcost=thiscost;                  costa=0;                  getcost();                  hasilakhir=costa;                  countsame=0;              }else{                  countsame++;                  //appowner.paint();             }             costa=0;         }         duration = (int) (system.currenttimemillis()-time);         stringbuffer sb = new stringbuffer();         (int i=0; i< appowner.sensorcount; i++){             sb.append("node address: " + appowner.sensornodelist[mem[i]].getaddress());             sb.append(" rssi: " + appowner.sensornodelist[mem[i]].getsignalstrength());             sb.append(" battery level: " + appowner.sensornodelist[mem[i]].getremainingbattery());             sb.append("\n");         }         string status = "ce finds solution after " + duration + " ms max rating= " + hasilakhir;        string migrationinfo = sb.tostring();        appowner.setstatus(status, "urutan rute migrasi: \n" + migrationinfo);      }  } 

this class want call constructor

public class cemobileagentmigrationplan extends jframe {     //protected sensornodeplacementmap map = null;     sensornode[] sensornodelist;     crossentropy worker;     private jtextarea textarea;     boolean started = false;     private jlabel status;     int sensorcount;      public cemobileagentmigrationplan(){         getcontentpane().setlayout(new borderlayout());         status = new jlabel("starting app...");         textarea = new jtextarea("listening... \b");         getcontentpane().add(status,borderlayout.south);         getcontentpane().add(textarea,borderlayout.center);         setsize(500,400);         settitle("cross entropy mobile agent itinerary planning");         this.setresizable(true);         setvisible(true);     }      public void setsensornodes(sensornode[] sensornodes){         this.sensornodelist = sensornodes;         this.sensorcount = this.sensornodelist.length;     }      public int getsensorcount(){         return sensorcount;     }      public sensornode[] getsensornodelist(){         return sensornodelist;     }      public void setstatus(string statustxt, string migrationinfo){         status.settext(statustxt);         textarea.settext(migrationinfo);     }      public void setsensornodelist(sensornode[] sensornodelist) {         this.sensornodelist = sensornodelist;     }      public void start(){ // yang ini tidak bisa         this.started=true;         //map.update(map.getgraphics());         //if (worker!= null)worker=null;         system.out.println("lol");         worker = new crossentropy(this); <<<<< troublemaker         system.out.println("lol1111");         worker.setpriority(thread.min_priority);         //map.update(map.getgraphics());         worker.start();     }   } 

i make similar class find out cause it, couldn't find :(

if code sample provided complete, you'll nullpointerexception when trying construct object. line

int max=appowner.sensorcount+populasi; 

will cause it, because appowner null when object constructed. properties initialized before constructor called. should calculate value in construtor itself, e.g.

int max;  public crossentropy(cemobileagentmigrationplan appowner){     system.out.println("hi !");     this.appowner=appowner;     max=appowner.sensorcount+populasi;     system.out.println("hi hi hello !");     this.sensornodes=appowner.sensornodelist;     system.out.println("hello !"); }