将字符串数组添加到JComboBox

Question

My Aim is to get a Value from an SQL table and add the value to a combobox

        Connection con;
        Statement st;
        ResultSet rs;
        con=DriverManager.getConnection("jdbc:mysql://localhost/needed","arv","");
        st=con.createStatement();
        rs= st.executeQuery("SELECT * FROM INVENTORY");
        List<String> l = new ArrayList();
        while(rs.next()){
            l.add(rs.getString("CAT"));
        }
        String[] h = l.toArray(new String[l.size()]);

        jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(h));  

But I'm not able to execute it since im getting a NPE at jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(h));

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at FilterTabs.<init>(FilterTabs.java:43)

How do i proceed after this and how should i solve this NPE?

Answer 1

Give this code snippet, the only thing that can be null in the expression jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(h)); is the jComboBox1 .

Make sure you initialize it before reaching this code snippet.