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up vote 1 down vote favorite

I've looked around and tried to solve this issue by recompiling my other classes etc but nothing seems to work.

I have two files, in SensorDataDisplay.java I have the following code:

private SensorSim[] sensors;

...

public void runSimulation(double numberOfSensors)  {
  sensors = new SensorSim[numOfSensors];
  int i = 0;

  for(i = 0; i<numOfSensors; i++) {
    sensors[i].SensorSim(sensorNom, sensorErr);
  }
}

And then in the same directory I have SensorSim.java compiled into SensorSim.class, the constructor is below.

public SensorSim(double n, double d) {
    if (probs == null)
      loadData();
    nominal = n; sd = d;
    rng = new Random();
    running = true;
}

This was working when I was just creating a single sensorSim. I recently added the array of sensorSims which is when I got this error:

$ javac SensorDataDisplay.java

SensorDataDisplay.java:44: cannot find symbol
symbol  : method SensorSim(double,double)
location: class SensorSim
      sensors[i].SensorSim(sensorNom, sensorErr);
            ^
1 error

Looking around I saw that it may have to do with older class files so I removed and recompiled the other files (SensorSim.class). Another possible reason that i read was to do with scope but it looks okay to me, i'm new to Java however. Why might this error may be occurring?

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4 Answers 4

up vote 2 down vote accepted

You try and run a method called SensorSim(double, double) on a SensorSim instance (sensors[i]), which does not even exist at this point.

If what you meant was creating a SensorSim instance at each array element,

sensors[i].SensorSim(sensorNom, sensorErr);

should become:

sensors[i] = new SensorSim(sensorNom, sensorErr);

What is more, your runSimulation() method takes a double as an argument and uses that to size an array (sensors = new SensorSim[numOfSensors];) : this double will be "downcast" to an int.

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Perfect compiled without issue. I'de since changed the double to an int when debugging but hadn't changed my post. Thanks very much. –  ubiQ Dec 30 '12 at 22:41
up vote 1 down vote

You're trying to call a constructor like this:

sensors[i].SensorSim(sensorNom, sensorErr);

That's not how you do it. I suspect you want:

sensors[i] = new SensorSim(sensorNom, sensorErr);
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up vote 1 down vote

Replace

sensors[i].SensorSim(sensorNom, sensorErr);

with

sensors[i] = new SensorSim(sensorNom, sensorErr);
share|improve this answer
up vote 1 down vote

You get the error because of this line of code:

sensors[i].SensorSim(sensorNom, sensorErr);

This will work, instead:

sensors[i] = new SensorSim(sensorNom, sensorErr);

Keep in mind that sensors[i] is like having for example

SensorSim s; 
s = new SensorSim(sensorNom, sensorErr);
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