if (materials == null || materials.size() == 0) return;
	public void setMaterials(Collection materials) {	    courseEquipmentPanel.removeAll();	    courseEquipmentJcb = new JComboBox(materialsName);	    courseEquipmentPanel.add(courseEquipmentJcb);	    courseEquipmentPanel.add(Box.createVerticalStrut(5));	    	    int cpt = 0;		int sizeMaterials = materials.size();				for(Iterator it = materials.iterator(); it.hasNext(); ) {			Material material = (Material) it.next();						int pos = -1;						for(int i = 1; i < this.materials.length; ++i) {				if (this.materials[i].equals(material))					pos = i;			}						if (cpt == 0) {				courseEquipmentJcb.setSelectedIndex(pos);    											if (cpt != (sizeMaterials-1))					courseEquipmentPlus.setText("x");  				}			else {				JComboBox jcb = new JComboBox(materialsName);								jcb.setSelectedItem(materialsName[pos]);								courseEquipmentPanel.add(jcb);				courseEquipmentPanel.add(Box.createVerticalStrut(5));								JButton plus;				if(cpt == (sizeMaterials-1))					plus = new JButton("+");				else					plus = new JButton("x");								plus.addActionListener(new ButtonPlusListener(courseEquipmentPlusPanel, courseEquipmentPanel, AMCWFrame, materialsName));				courseEquipmentPlusPanel.add(plus);				courseEquipmentPlusPanel.add(Box.createVerticalStrut(5));			}			cpt++;		}	}