private void updateTarget() { if (substance == null) { return; } if (metric == null) { targetObjective = null; return; } if (objective == null) { targetObjective = null; return; } double weight = Double.parseDouble(weightField.getText()); if (weight <= 0) { targetObjective = null; return; } targetObjective = new TargetDoseObjective(metric, objective, weight); textField.setText(targetObjective.toString()); }