public void addListener() {
		itemtf[4].addFocusListener(new FocusListener() {
			@Override
			public void focusLost(FocusEvent arg0) {
				if (!itemtf[4].getText().equals("")) {
					String name = logic.showTeacherName(itemtf[4].getText());
					itemtf[5].setText(name);
				}
			}

			@Override
			public void focusGained(FocusEvent arg0) {

			}
		});
		confirmBtn.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				for (int i = 0; i < itemtf.length; i++) {
					String item = itemtf[i].getText();
					if (item.equals("") || item.equals("null")) {
						showFeedBack(Feedback.ITEM_EMPTY);
						itemInfo = null;
						break;
					}
					itemInfo += item + "；";
				}
				if (itemInfo != null) {
					Feedback fb = logic.addCommonCourse(itemInfo);
					JOptionPane.showMessageDialog(frame, fb.getContent());
					frame.setVisible(false);
					frame.dispose();
				}
			}
		});
		cancelBtn.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				frame.setVisible(false);
				frame.dispose();
			}
		});
	}