Unknown NullPointerException from G4P GUI Builder

Processing Libraries
1

Hi there!

I want to fix the GUI error for the Magnifying Glass burning simulation program to run smoothly.

When changing anything in the GUI from the G4P GUI Builder tool, the program always crashes with a NullPointerException in 2 - 5 minutes and does not highlight the problematic line of code.

exception
exception1912×782 115 KB

I tried:

  • searching for the problem online and following solutions
  • defining all variables used in the program
  • using try-catch statements
  • recreating the GUI

but they were unhelpful.

Code for GUI Event Handlers:

public void pauseButtonClicked(GButton source, GEvent event) { //_CODE_:pauseButton:875606:
  // If the program is running, stop 
  if(running) {
    running = !running;
    noLoop();
    pauseButton.setText("Resume");
  }
  
  // If the program is paused, run
  else {
    running = !running;
    loop();
    pauseButton.setText("Pause");
  }
} //_CODE_:pauseButton:875606:

public void massSliderChanged(GCustomSlider source, GEvent event) { //_CODE_:massSlider:958855:
  println("massSlider - GCustomSlider >> GEvent." + event + " @ " + millis());
} //_CODE_:massSlider:958855:

public void focalDistanceSliderChanged(GCustomSlider source, GEvent event) { //_CODE_:focalDistanceSlider:299666:
  
} //_CODE_:focalDistanceSlider:299666:

public void xPositionSliderChanged(GCustomSlider source, GEvent event) { //_CODE_:xPositionSlider:537864:
  println("xPositionSlider - GCustomSlider >> GEvent." + event + " @ " + millis());
} //_CODE_:xPositionSlider:537864:

public void yPositionSliderChanged(GCustomSlider source, GEvent event) { //_CODE_:yPositionSlider:494398:
  println("yPositionSlider - GCustomSlider >> GEvent." + event + " @ " + millis());
} //_CODE_:yPositionSlider:494398:

public void beamIntensitySliderChanged(GCustomSlider source, GEvent event) { //_CODE_:beamIntensitySlider:967979:
  float num = beamIntensitySlider.getValueF();
  
  if(num > 0.1 && num < 2 ) {
    material.beamIntensity = num;
  }
} //_CODE_:beamIntensitySlider:967979:

public void materialChoiceClicked(GDropList source, GEvent event) { //_CODE_:materialChoice:221684:
  if (materialChoice.getSelectedText().equals("Ant")) {
    currentMaterial = "ant";
  }
  
  else if (materialChoice.getSelectedText().equals("Paper")) {
    currentMaterial = "paper";
  }
  
  else if (materialChoice.getSelectedText().equals("Grass")) {
    currentMaterial = "grass";
  }
  
  else {
    currentMaterial = "wood";
  }
  
  reset();
} //_CODE_:materialChoice:221684:

public void glassQualityChanged(GDropList source, GEvent event) { //_CODE_:glassQuality:419836:
  if (glassQuality.getSelectedText().equals("Clear")) {
    magnifyingGlass.lensQuality = "Clear";
    magnifyingGlass.transparency = 1;
  }
  
  else if (glassQuality.getSelectedText().equals("Impurities")) {
    magnifyingGlass.lensQuality = "Impurities";
    magnifyingGlass.transparency = 0.75;
  }
  
  else if (glassQuality.getSelectedText().equals("Dirty")) {
    magnifyingGlass.lensQuality = "Dirty";
    magnifyingGlass.transparency = 0.5;
  }
} //_CODE_:glassQuality:419836:

public void temperatureSliderChanged(GSlider source, GEvent event) { //_CODE_:temperatureSlider:230192:
  surroundingTemperature = temperatureSlider.getValueI();
  currentTemperature.setText(str(surroundingTemperature));
  reset();
  println("slider1 - GSlider >> GEvent." + event + " @ " + millis());
} //_CODE_:temperatureSlider:230192:

What is the most efficient fix if we must stick to the G4P GUI builder?

2

Welcome to the forum - let’s get started on your problem.

It is not clear whether the error occurs

  1. when you are actually editing the interface with GUI Builder tool, or
  2. while the actual sketch is running.

If it is (2) does it happen when you interact with a particular control?

If you run the program and don’t interact with the GUI i.e. leave the controls alone does this error occur?

When you reply to these questions I will have a better idea of where to look for a solution.