JTree data from database

Question

Hi all,

I'm working on the example at http://java.sun.com/docs/books/tutorial/uiswing/examples/components/GenealogyExampleProject/src/components/GenealogyExample.java

I wanted to customize it in a way the data are pulled from a table instead (folder_id, folder_name, parent_id[foreign key to determine parent] .

Here is my code

 public Person getGenealogyGraph() throws SQLException {
    Connection con=null;
    Statement st=null;
    ResultSet rs=null;

    String driver ="com.mysql.jdbc.Driver";
    String url="jdbc:mysql://localhost:3306/";
    String db="java";
    con=DriverManager.getConnection(url + db, "root", "");
    ArrayList list=new ArrayList();

    try {
        String sql="Select * from folder";
        st=con.createStatement();
        rs=st.executeQuery(sql);
        list.add("Current Folders");
        while(rs.next()) {
            String folderName = rs.getString("folder_name");
            list.add(folderName);
           // System.out.println(folderName);
            //Person a1 = new Person(folderName);

        }


    } catch (Exception e) {
        System.out.println(e);
    }
    rs.close();
    st.close();
    con.close();

       Object hierarchy[]=list.toArray();
        for(int i=1; i<hierarchy.length; i++) {
           Person a+i=new Person(hierarchy[i]);
        }

If I hardcode it as Person a1 = new Person("Jack (great-granddaddy)"); , it works fine. However, I wanted to put it in a loop, with the variable i :-

Object hierarchy[]=list.toArray();
        for(int i=1; i<hierarchy.length; i++) {
           Person a+i=new Person(hierarchy[i]);
 }

How can I make the variable i and the "a" to be combined together? In PHP, we usually combine them with a "." , eg "a".$i;

Thanks :) Any other example on creating trees from database is greatly appreciated too. Thanks in advance

Answer 1

I'm not sure about what you're trying to do. But if you want to assign a dynamic name to your variables you should store your objects in a associative array (java.util.Map)

Map<String,Person> map= new HashMap<String,Person>();
(...)
map.put("a"+i,new Person(hierarchy[i]));