dynamic Jtree from database

Question

I have a database table named tree1, which has a table names student_details.This table has 3 columns student_name,student_details,student_phone

Now, am able to retrieve student details from the database but only in static way.

Question is when I insert a new student detail row {student_name,student_details,student_phone} I want it to show on my Jtree. Although Hashmap is the solution I am not able to understand how to use hashmap in a Jtree to create dynamic nodes.

below is the code from which I could do a static Jtree, and i want to make it dynamic. Can anyone tell me how to do this with a code sample?

package tree_try;


import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.beans.Statement;
import java.sql.*;
import java.util.ArrayList;
import java.util.Iterator;
import javax.swing.*;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.*;


public class SimpleTree extends JFrame
{
   public Connection connect = null;


   public Statement statement = null;
   public Statement statement2 = null;
    public Statement statement3 = null;
      public Statement statement4 = null;
   public Statement statement5 = null;
    public Statement statement6 = null;

   public ResultSet resultSet = null;
   public ResultSet resultSet2 = null;
    public ResultSet resultSet3 = null;
     public ResultSet resultSet4 = null;
   public ResultSet resultSet5 = null;
    public ResultSet resultSet6 = null;



   public ArrayList arrayList = new ArrayList();
   public ArrayList arrayList2 = new ArrayList();
   public ArrayList arrayList3 = new ArrayList();
   public ArrayList arrayList4 = new ArrayList();

   static String store[] = new String[10];
   static String store2[] = new String[10];
   static String store3[] = new String[10];

   //for the panel

   static String store4[] = new String[10];
   static String store5[] = new String[10];
   static String store6[] = new String[10];
    static String store7[] = new String[10];

   //for panel over


   int i=0;
   int i1=0;
   int i2=0;
   int i3=0;



    JPanel jp1 = new JPanel();
    JPanel jp2 = new JPanel();
    JFrame jf1 = new JFrame();

    JButton jb1 = new JButton("Save");
       JButton jb2 = new JButton("Cancel");

    JTextField jt1= new JTextField();
    JTextField jt2 = new JTextField();
    JTextField jt3= new JTextField();
    JTextField jt4 = new JTextField();



    JLabel jl0 = new JLabel();

    JLabel jl1 = new JLabel("Name : ");
    JLabel jl2 = new JLabel("Adress : ");
    JLabel jl3 = new JLabel("Phone Number : ");
    JLabel jl4 = new JLabel("Other Deatils : ");
    JLabel jl5 = new JLabel("");


  public static void main(String[] args)
  {
    new SimpleTree();
  }

  public SimpleTree() 
  {

    super("Schools database");
    WindowUtilities.setNativeLookAndFeel();
    addWindowListener(new ExitListener());





     //db part
      try 
                {
            Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance();
            connect = DriverManager.getConnection("jdbc:derby://localhost:1527/treedata1","suraj","suraj");
            PreparedStatement statement = connect.prepareStatement("SELECT * from school_details");
                        PreparedStatement statement2 = connect.prepareStatement("select student_name from student_details where s_id =1");   
                         PreparedStatement statement3 = connect.prepareStatement("select student_name from student_details where s_id =2");   

                         //for the panel display


                         //PreparedStatement statement5 = connect.prepareStatement("select student_name from student_details where s_id =1");   
                         //PreparedStatement statement6 = connect.prepareStatement("select student_name from student_details where s_id =2");



            resultSet = statement.executeQuery();
            while (resultSet.next()) 
                        {
                String sname = resultSet.getString("school_name");
                String sid = resultSet.getString("s_id");
                arrayList.add(sname);
                                System.out.println("this is stsement one"+sname);
                                //arrayList.add(number);

            }

                        resultSet2 = statement2.executeQuery(); 
                        while (resultSet2.next())
                        {
                                String user2 = resultSet2.getString("student_name");
                //int  number2 = resultSet2.getInt("s_id");
                                arrayList2.add(user2);
                                System.out.println("this is stsement two"+user2);
                        }
                      //  System.out.println(arrayList); 
                         resultSet3 = statement3.executeQuery(); 
                        while (resultSet3.next())
                        {
                                String user3 = resultSet3.getString("student_name");
                //int  number2 = resultSet2.getInt("s_id");
                                arrayList3.add(user3);
                                System.out.println("this is stsement three"+user3);
                        }
                        System.out.println("this is after statement 3 before 4");



        } 
                catch (Exception e2) 
                {
            e2.printStackTrace();
        } 





      //
    Iterator it = arrayList.iterator();
    while (it.hasNext()) 
    {
         store[i]= (String) it.next();
         i++; 
                 //System.out.println(it.next());
    }


    Iterator it2 = arrayList2.iterator();
    while (it2.hasNext()) 
    {
         store2[i1]= (String) it2.next();
         i1++;        
        //System.out.println(it.next());
    }

     Iterator it3 = arrayList3.iterator();
    while (it3.hasNext()) 
    {
         store3[i2]= (String) it3.next();
         i2++;        
       // System.out.println(it.next());
    }








    // ------------------------- Visible Settings start here --------------------//

     Object[] hierarchy ={"Click for schools",new Object[] {store[0],new Object[] { "Student Details",store2[0],store2[1] } },new Object[] { store[1],new Object[] { "Student Details",store3[0],store3[1]}}};
    DefaultMutableTreeNode root = processHierarchy(hierarchy);
    final JTree tree = new JTree(root);

   // setSize(275, 300);
    jp1.setSize(50,50);
    jp1.setBackground(Color.WHITE);
    jf1.setExtendedState(Frame.MAXIMIZED_BOTH);
    jf1.setLayout(new GridLayout(1,2));
    jf1.setVisible(true);
    jf1.add(new JScrollPane(tree), BorderLayout.WEST);
    jf1.add(jp1);
    jp1.setLayout(null);

  jl0.setBounds(10,1,500,100);  
  jp1.add(jl0);


 jl1.setBounds(55,90,150,100);   
 jt1.setBounds(225,130, 155, 25);

 jp1.add(jl1);
 jp1.add(jt1);

 jl2.setBounds(55,160, 150, 100);
 jt2.setBounds(225,200, 155, 25);

 jp1.add(jl2);
 jp1.add(jt2);

 jl3.setBounds(55,230,150,100);
 jt3.setBounds(225,270, 155, 25);

  jp1.add(jl3);
  jp1.add(jt3);

 jl4.setBounds(55,295, 150, 100);
 jt4.setBounds(225,330, 155, 25);

  jp1.add(jl4); 
  jp1.add(jt4);

  jb1.setEnabled(false);
  jb2.setEnabled(false);

 jb1.setBounds(150,430, 100, 50);
 jb2.setBounds(350,430, 100, 50);

  jp1.add(jb1);
  jp1.add(jb2);

  //-----------------Visible setting stop here--------------------------//

   //------------------- Element actions here------------------------//


    jt1.addFocusListener(new FocusListener() {

            @Override
            public void focusGained(FocusEvent e) 
            {
             jb1.setEnabled(true);
             jb2.setEnabled(true);    
            }

            @Override
            public void focusLost(FocusEvent e) 
            {
                jb1.setEnabled(false);
                jb2.setEnabled(false); 
            }
        });

    //now for the tree

    tree.addTreeSelectionListener(new TreeSelectionListener() {

            @Override
            public void valueChanged(TreeSelectionEvent e) {
                jf1.dispose();
                //jl0.setText("Displaying information About :  "+tree.getLastSelectedPathComponent().toString());
                store7[0]= tree.getLastSelectedPathComponent().toString(); 
                System.out.println("in store 7 of 0"+store7[0]);
                dbaction db = new dbaction(store7[0]);
            }
        }); 

   }
//------------------------------------end of action listening-------------------------

  private DefaultMutableTreeNode processHierarchy(Object[] hierarchy) 
  {
    DefaultMutableTreeNode node = new DefaultMutableTreeNode(hierarchy[0]);DefaultMutableTreeNode child;
    for(int i=1; i<hierarchy.length; i++) 
    {
      Object nodeSpecifier = hierarchy[i];
      if (nodeSpecifier instanceof Object[])  // Ie node with children
        child = processHierarchy((Object[])nodeSpecifier);
      else
        child = new DefaultMutableTreeNode(nodeSpecifier); // Ie Leaf
      node.add(child);
    }
    return(node);
  }

    private void close() 
    {
        try {
            if (resultSet != null) 
                        {
                resultSet.close();
            }
            if (statement != null) 
                        {
                //statement.
            }
            if (connect != null) 
                        {
                connect.close();
            }
        } 
        catch (Exception e3) 
                {
        e3.printStackTrace();
        }
    }
}

of course dbaction.java is where I connect to the database and get details.

Answer 1

The JTree tutorial to which Max linked has a section covering 'Dynamic updates of a JTree' which contains the necessary snippets on how to update a TreeModel. The basic idea is that you update the model behind the JTree (the TreeModel) and fire the correct events from the TreeModel. The JTree will listen for those events and update itself accordingly.

Next to that, some other advise:

• You should only access Swing components on the Event Dispatch Thread (EDT), which is currently not the case in your example. See the Concurrency in Swing tutorial for more information
• The moment you adjust your main method to run on the EDT, you should avoid the long running taks (the database access), as it will block the EDT and leave you with an unresponsive UI (as Max already indicated).
• You should avoid the null layout and the manual placing of all your components using setBounds. Otherwise simple things like resizing the UI will results in a messed-up layout. Use a LayoutManager instead. The usage of LayoutManagers is also covered in the 'LayoutManager tutorial' on the Oracle site.

Answer 2

It is best to create a data model for the tree. How to Use Trees tutorial has good examples. Also go through Understanding the TreeModel for more details.

By the way, don't execute long running tasks such as accessing database on Event Dispatch Thread . Look into SwingWorker for such tasks.