AddItemListener() for array of checkboxes

Question

I'm new to interface design and believe this to be how to add an item listener to an Array of JcheckBoxes, Java has other ideas, could anybody show me where i am going wrong.
The error reported is in the for loop, line 3 of the code below:
//Register a listener for the check boxes.
        for (int i=0; i<numberOfDrugs; i++){
     drugCheck.addItemListener(this);
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
/** Listens to the check boxes. */
public void itemStateChanged(ItemEvent e){
Object source = e.getItemSelectable();
for (int i =0; i<numberOfDrugs; i++){
     if (source == drugCheck) {
     if (drugCheck[i].isSelected() == true){
     drugsSelected+=1;
     drugEffectiveness[i].setEnabled(true);
     drugCumDosage[i].setEnabled(true);
     else {
     drugsSelected-=1;
     drugEffectiveness[i].setEnabled(false);
     drugCumDosage[i].setEnabled(false);

Answer 1

Checkboxes are created thus:
JCheckBox[] drugCheck = new JCheckBox[numberOfDrugs];
//Creates 'numberOfDrugs' amount of checkboxes
for (int i=0; i<numberOfDrugs; i++){
             drugCheck[i] = new JCheckBox("checkbox" + i);
     getContentPane().add(drugCheck);
The error message reads as below:
d:\documents\== project ==>javac gui/*.java
gui/A.java:78: addItemListener(java.awt.event.ItemListener) in javax.swing.AbstractButton cannot be applied to (gui.A)
drugCheck[i].addItemListener(this);
So i would go along with the THIS part not being an item listener, which is where the problem lies.