java - why the array reinitialize each time? -

i've question you:

i wrote code:

public class mainactivity extends activity implements sensoreventlistener {     private sensormanager msensormanager;     private sensor msensor;     arraylist<string> oldvalue  = new arraylist<string>();     int count;      @override     public void oncreate(bundle savedstate) {         super.oncreate(savedstate);         setcontentview(r.layout.activity_main);         msensormanager = (sensormanager) getsystemservice(context.sensor_service);         msensor = msensormanager.getdefaultsensor(sensor.type_accelerometer);         msensormanager.registerlistener((sensoreventlistener) this, msensor,         sensormanager.sensor_delay_normal);         count = 0;         //oldvalue = null;      }      @override     protected void onpause() {         super.onpause();         //msensormanager.unregisterlistener(this);     }      public void onaccuracychanged(sensor sensor, int accuracy) {      }      public void onsensorchanged(sensorevent event) {         string x,y,z;         float xnum,ynum,znum;         textview xtextview,ytextview,ztextview = new textview(this);          if (oldvalue == null || oldvalue.size()<1) {         string statoarray = "null or 0";         toast.maketext(this, statoarray, toast.length_short)           .show();         }         else {             string statoarray = string.valueof(oldvalue.size());             toast.maketext(this, statoarray, toast.length_short)               .show();         }           if (oldvalue.size()<2)          {             xtextview=(textview)findviewbyid(r.id.x);              ytextview=(textview)findviewbyid(r.id.y);             ztextview=(textview)findviewbyid(r.id.z);              xnum = event.values[0];             ynum = event.values[1];             znum = event.values[2];              oldvalue.add(string.valueof(xnum));         oldvalue.add(string.valueof(ynum));         oldvalue.add(string.valueof(znum));           x = float.tostring(math.round(xnum));         y = float.tostring(math.round(ynum));;         z = float.tostring(math.round(znum));;          xtextview.settext(x);         ytextview.settext(y);         ztextview.settext(z);            }          //toast.maketext(this, "pieno", toast.length_short)         //.show();     }   } 

so don't understand because each time change value of x y z, array reinitialize itself...

i've necessity store more cicle in array value

thanks lot

because initializing them inside onsensorchanged()

so when device moves little, onsensorchanged() called ,

 string x,y,z;         float xnum,ynum,znum;         textview xtextview,ytextview,ztextview = new textview(this); 

these , other things initialized onsensorchanged() reinitialized

so declare these inside class 

and use inside class