2. void readArduino(){
3. 
   
4.  // Throw out the first reading, in case we started reading 
5.  // in the middle of a string from the sender.
6. 
   
7.  //get the sensor and actuator data from the serial port
8.  if (comPort4.available() > 0) 
9.  {
10.  getRawArduino = comPort4.readString();
11.  
12.  String[] readList = splitTokens(getRawArduino);
13.  for (int n = 0; n < readList.length; n++){
14.    if (readList[n] != null){
15.   //convert strings to floats
16.      intLightSens1 = int(readList[0]);      // intLightSens1
17.      intLightSens2 = int(readList[1]);      // intLightSens2
18.      intLightSens3 = int(readList[2]);      // intLightSens3
19.      
20.      avgInteriorLight = int(readList[3]);   // avgInteriorLight
21.     
22.      extLightSens1 = int(readList[4]);      // extLightSens1
23.      extLightSens2 = int(readList[5]);      // extLightSens2
24.      extLightSens3 = int(readList[6]);      // extLightSens3
25.      extLightSens4 = int(readList[7]);      // extLightSens4
26.      extLightSens5 = int(readList[8]);      // extLightSens5
27.      
28.      solarPosition = int(readList[9]);      // solarPosition
29.      actuatorPercent = int(readList[10]);   // actuatorPercent
30.     
31.      temp_c_indoor = float(readList[11]);             // temp_c_indoor
32.      temp_f_indoor = float(readList[12]);             // temp_f_indoor
33.      dewpoint_f_indoor = float(readList[13]);         // dewpoint_f_indoor
34.      relative_humidity_indoor = float(readList[14]);  // relative_humidity_indoor
35.      }
36.    
37.    else{
38.      println ("Not getting all 15 values from Arduino");
39.    }
40.   }
41.  }
42. }

I'll have to let it run for a while to confirm that this is my fix.  I'll let you know how it works out.

1. String[] readList = splitTokens(getRawArduino);
2.  for (int n = 0; n < 15; n++){
3.    // check 1: ...only if it's within the current length of the readList...
4.    // check 2: ...and it's not null... (not really necessary, but just to be double-safe)
5.    if (n < readList.length && readList[n] != null){
6.      floatList[temp_c_indoor, temp_f_indoor, dewpoint_f_indoor, relative_humidity_indoor] = float(readList[11, 12, 13, 14]); // set the value
7.      intList[intLightSens1, intLightSens2, intLightSens3, avgInteriorLight, extLightSens1, extLightSens2, extLightSens3, extLightSens4, extLightSens5, solarPosition, actuatorPercent] = int(readList[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
8.      

     

Perhaps the above solution is better for you now. But let me just make an argument for using an array. An array is just a number of variables, but it makes code simpler and shorter. For example, if you had 100 incoming variables. Would you type 100 long variable names? And write 100 lines like this?

intLightSens78 = int(readList[77]);      // intLightSens78

But indeed, the downside of an array is that you would have to use floatArray[0] instead of a variable name like intLightSens1.

2. float[] readArduinoFloat = new float[4];
3. int[] readArduinoInt= new int[11];
4. 
   
5. void readArduino(){
6. 
   
7.  // Throw out the first reading, in case we started reading 
8.  // in the middle of a string from the sender.
9. 
   
10.  //get the sensor and actuator data from the serial port
11.  if (comPort4.available() > 0) 
12.  {
13.  getRawArduino = comPort4.readString();
14.  
15.  String[] readList = splitTokens(getRawArduino);
16.  for (int n = 0; n < 15; n++){
17.    // check 1: ...only if it's within the current length of the readList...
18.    // check 2: ...and it's not null... (not really necessary, but just to be double-safe)
19.    if (n < readList.length && readList[n] != null){
20.                                                                 //reference to arduino values
21.      readArduinoFloat = (float[])subset(readList[n], 11, 4);    //temp_c_indoor, temp_f_indoor, dewpoint_f_indoor, relative_humidity_indoor
22.      readArduinoInt = (int[])subset(readList[n], 0, 11);        //intLightSens1, intLightSens2, intLightSens3, avgInteriorLight, extLightSens1, extLightSens2, extLightSens3, extLightSens4, extLightSens5, solarPosition, actuatorPercent     
23.      }
24.    
25.    else{
26.       readArduinoFloat[4] = -1; // otherwise set to a non-value so elsewhere you know nothing came in
27.       readArduinoInt[11] = -1;
28.       println("missing readList[" + n + "]"); // print warning to console   
29.     }
30.    }
31.   }
32.  }