Java 如何在JTree上显示动态更新？/如何刷新或重新加载JTree？
应用程序很简单，一个框架中有两个面板Java 如何在JTree上显示动态更新？/如何刷新或重新加载JTree？,java,swing,jtree,Java,Swing,Jtree,应用程序很简单，一个框架中有两个面板 第一个面板，从数据库中检索所有学生，使用多个hashmap获取父和子排列，并在树上显示它 第二个面板，当您单击某个学生时，该学生的所有详细信息（selectionlistener）显示在文本框中 现在，当我在第二个面板上更改学生的名字时，数据库会正确地更新它，但树会显示旧的值 我尝试了treepanel.reload（），我尝试了treemodellistener 有人能帮我吗。在网上浏览了很多解决方案后，所有的解决方案都是局部的，我无法将它们应用到我的代码
Main frame.java
/**
* @author Suraj Baliga
*
* Returns a JFrame with two Panels one having the Jtree and other
* having the details of the selected tree component.It also has dynamic tree and
* dynamic textbox where updation of text in the textbox will change the value in
* databse on click of save button.The JDBC localhost url may change with each machine
* as the database location and port number may vary.
*/
package Student_Details;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import javax.swing.*;
import javax.swing.tree.DefaultMutableTreeNode;
import org.apache.commons.collections.MultiHashMap;
public final class Main_frame extends JPanel
{
String sname,sschool;
ArrayList StudName_arrylst = new ArrayList();
ArrayList SchlName_arrylst = new ArrayList();
ArrayList StudDetailTxtFld_arrylst = new ArrayList();
static public Connection connect,connect_update;
public ResultSet resultSet;
public static ResultSet resultset2;
MultiHashMap SchlStud_hashmap = new MultiHashMap();
int i,j,k,k2,z;
DefaultMutableTreeNode tree_parent;
int SchlName_arylist_length, StudNamearrylst_length;
private tree_generation treePanel;
static JButton save_button = new JButton("Save");
static JButton cancel_button = new JButton("Cancel");
static JTextField studName_txtbox= new JTextField();
static JTextField studAddress_txtbox = new JTextField();
static JTextField studOthr_txtbox = new JTextField();
static public String user_name;
static public String user_add;
static public String user_other;
static JLabel name_label = new JLabel("Name : ");
static JLabel address_label = new JLabel("Adress : ");
static JLabel other_label = new JLabel("Other Deatils : ");
static String studDetailsTxtbox_disp[] = new String[10];
static String studDetailsTxtbx_disp_db[] = new String[10];
static String studDetailsTxtbxchange[] = new String[10];
public JPanel panel;
static JPanel panel_boxes = new JPanel();
public Main_frame()
{
super(new BorderLayout());
//Create the components.
treePanel = new tree_generation();
populateTree(treePanel);
//Lay everything out.
treePanel.setPreferredSize(new Dimension(300, 150));
add(treePanel, BorderLayout.WEST);
panel = new JPanel(new GridLayout(1, 2));
add(panel, BorderLayout.CENTER);
}
public void populateTree(tree_generation treePanel)
{
try
{
Class.forName("org.apache.derby.jdbc.ClientDriver");
connect = DriverManager.getConnection("jdbc:derby://localhost:1527/treedata2", "suraj", "suraj");
PreparedStatement AllStuddetails = connect.prepareStatement("SELECT * from student_details");
resultSet = AllStuddetails.executeQuery();
while (resultSet.next())
{
sname = resultSet.getString(1);
sschool = resultSet.getString(3);
SchlStud_hashmap.put(sschool, sname);
}
}
catch (Exception e)
{
}
Set keySet = SchlStud_hashmap.keySet();
Iterator keyIterator = keySet.iterator();
while (keyIterator.hasNext())
{
Object key = keyIterator.next();
SchlName_arrylst.add(key);
Collection values = (Collection) SchlStud_hashmap.get(key);
Iterator valuesIterator = values.iterator();
while (valuesIterator.hasNext())
{
StudName_arrylst.add(valuesIterator.next());
}
SchlName_arylist_length = SchlName_arrylst.size();
StudNamearrylst_length = StudName_arrylst.size();
String schlname_tree[] = new String[SchlName_arylist_length];
String studname_tree[] = new String[StudNamearrylst_length];
Iterator SchlName_iterator = SchlName_arrylst.iterator();
i = 0;
while (SchlName_iterator.hasNext())
{
schlname_tree[i] = SchlName_iterator.next().toString();
}
Iterator StudName_iterator = StudName_arrylst.iterator();
j = 0;
while (StudName_iterator.hasNext())
{
studname_tree[j] = StudName_iterator.next().toString();
j++;
}
for (k = 0; k < schlname_tree.length; k++)
{
tree_parent = treePanel.addObject(null, schlname_tree[k]);
for (k2 = 0; k2 < studname_tree.length; k2++)
{
treePanel.addObject(tree_parent, studname_tree[k2]);
}
}
StudName_arrylst.clear();
SchlName_arrylst.clear();
}
}
/**
* Create the GUI and show it.
*/
private static void createAndShowGUI()
{
//Create and set up the window.
JFrame frame = new JFrame("Student Details");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create and set up the content pane.
Main_frame newContentPane = new Main_frame();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
panel_boxes.setLayout(null);
name_label.setBounds(55,90,150,100);
studName_txtbox.setBounds(225,130, 155, 25);
panel_boxes.add(name_label);
panel_boxes.add(studName_txtbox);
address_label.setBounds(55,160, 150, 100);
studAddress_txtbox.setBounds(225,200, 155, 25);
panel_boxes.add(address_label);
panel_boxes.add(studAddress_txtbox);
other_label.setBounds(55,220, 150, 100);
studOthr_txtbox.setBounds(225,270, 155, 25);
panel_boxes.add(other_label);
panel_boxes.add(studOthr_txtbox);
save_button.setBounds(150,350, 100, 50);
cancel_button.setBounds(350,350, 100, 50);
panel_boxes.add(save_button);
panel_boxes.add(cancel_button);
frame.add(panel_boxes);
//Display the window.
frame.pack();
frame.setSize(1000,700);
frame.setVisible(true);
save_button.setEnabled(false);
cancel_button.setEnabled(false);
studName_txtbox.addFocusListener(new FocusListener()
{
@Override //since some additional functionality is added by the user to
//the inbuilt function @override notation is used
public void focusGained(FocusEvent e)
{
save_button.setEnabled(true);
cancel_button.setEnabled(true);
}
@Override
public void focusLost(FocusEvent e)
{
System.out.println("out of focus textbox");
}
});
studAddress_txtbox.addFocusListener(new FocusListener() {
@Override
public void focusGained(FocusEvent e)
{
save_button.setEnabled(true);
cancel_button.setEnabled(true);
}
@Override
public void focusLost(FocusEvent e)
{
save_button.setEnabled(false);
cancel_button.setEnabled(false);
}
});
studOthr_txtbox.addFocusListener(new FocusListener() {
@Override
public void focusGained(FocusEvent e)
{
save_button.setEnabled(true);
cancel_button.setEnabled(true);
}
@Override
public void focusLost(FocusEvent e)
{
save_button.setEnabled(false);
cancel_button.setEnabled(false);
}
});
cancel_button.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(e.getSource()== cancel_button )
{
clear_textboxes();
}
}
} );
save_button.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
if(e.getSource()== save_button )
{
selectionButtonPressed();
}
}
} );
}
public void fill_textboxes(ArrayList a1)
{
Iterator alldetails = a1.iterator();
z=0;
while (alldetails.hasNext())
{
studDetailsTxtbx_disp_db[z]= (String) alldetails.next();
System.out.println("this is the Detail : "+studDetailsTxtbx_disp_db[z]);
z++;
}
studName_txtbox.setText(studDetailsTxtbx_disp_db[0]);
studAddress_txtbox.setText(studDetailsTxtbx_disp_db[1].toString());
studOthr_txtbox.setText(studDetailsTxtbx_disp_db[2]);
}
public static void selectionButtonPressed()
{
studDetailsTxtbxchange[0]=studName_txtbox.getText();
studDetailsTxtbxchange[1]=studAddress_txtbox.getText();
studDetailsTxtbxchange[2]=studOthr_txtbox.getText();
try
{
if((studDetailsTxtbxchange[0].equals(""))||(studDetailsTxtbxchange[0] == null)||(studDetailsTxtbxchange[1].equals(""))||(studDetailsTxtbxchange[1] == null)||(studDetailsTxtbxchange[2].equals(""))||(studDetailsTxtbxchange[2] == null))
{
JOptionPane.showMessageDialog(null,"One of the Fields is Blank","Error",JOptionPane.ERROR_MESSAGE);
}
else
{
System.out.println("control here inside else baby..that has : : "+studDetailsTxtbxchange[0]);
Class.forName("org.apache.derby.jdbc.ClientDriver");
connect_update = DriverManager.getConnection("jdbc:derby://localhost:1527/treedata2", "suraj", "suraj");
PreparedStatement execqry = connect.prepareStatement("select * from student_details where student_name='"+studDetailsTxtbxchange[0]+"'");
resultset2=execqry.executeQuery();
System.out.println("control at end if else");
if(resultset2.next())
{
JOptionPane.showMessageDialog(null,"Sorry This name already exists","Error",JOptionPane.ERROR_MESSAGE);
}
else
{
System.out.println("control here");
Class.forName("org.apache.derby.jdbc.ClientDriver");
connect_update = DriverManager.getConnection("jdbc:derby://localhost:1527/treedata2", "suraj", "suraj");
PreparedStatement updateQry = connect.prepareStatement("UPDATE student_details SET student_name='"+studDetailsTxtbxchange[0]+"',student_address='"+studDetailsTxtbxchange[1]+"',student_school='"+studDetailsTxtbxchange[2]+"' WHERE student_name='"+user_name+"' and student_address='"+user_add+"'and student_school='"+user_other+"'");
updateQry.executeUpdate();
JOptionPane.showMessageDialog(null,"Record Updated!","UPDATED",JOptionPane.OK_OPTION);
tree_generation.loadit();
}
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
public static void clear_textboxes()
{
studName_txtbox.setText(studDetailsTxtbx_disp_db[0]);
studAddress_txtbox.setText(studDetailsTxtbx_disp_db[1].toString());
studOthr_txtbox.setText(studDetailsTxtbx_disp_db[2]);
}
void dbaction(String string)
{
studDetailsTxtbox_disp[0]= string;
System.out.println("This is the stuff :" + studDetailsTxtbox_disp[0]);
try
{
Class.forName("org.apache.derby.jdbc.ClientDriver").newInstance();
connect = DriverManager.getConnection("jdbc:derby://localhost:1527/treedata2","suraj","suraj");
PreparedStatement statement4 = connect.prepareStatement("SELECT * from student_details where student_name ='"+studDetailsTxtbox_disp[0]+"'");
resultSet = statement4.executeQuery();
while(resultSet.next())
{
user_name = resultSet.getString("student_name");
StudDetailTxtFld_arrylst.add(user_name);
System.out.println("name :"+user_name);
user_add = resultSet.getString("student_address");
StudDetailTxtFld_arrylst.add(user_add);
System.out.println("address : "+ user_add);
user_other = resultSet.getString("student_school");
StudDetailTxtFld_arrylst.add(user_other);
System.out.println("school : "+user_other);
}
}
catch (Exception e1)
{
e1.printStackTrace();
}
fill_textboxes(StudDetailTxtFld_arrylst);
}
public static void main(String[] args)
{
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run()
{
createAndShowGUI();
}
});
}
}
create table student_details(student_name varchar(20),student_address varchar(30),student_school varchar(20));
insert into student_details values('suraj','mangalore','dps');
insert into student_details values('prassana','Bangalore lalbagh 23/16 2nd main road','dps');
insert into student_details values('deepika','Mangalore kadri park , 177b','dav');
insert into student_details values('sujith','delhi , rajinder nagar, d black','dav');
insert into student_details values('sanjay','bombay marina drive, 12/34','dav');
insert into student_details values('suresh','jaipur , lalbagh cjhowki','kv');
insert into student_details values('manu','surat, pune warior house','kv');
insert into student_details values('tarun','chennai, glof club','salwan');
insert into student_details values('vinay','haryana, indutrial area','hindu senior');
insert into student_details values('veeru','trivendrum, kottayam 12/77','canara')
好的，我想我在你的代码中发现了什么不起作用，但是你可能应该自己试试并确认一下
Class.forName("org.apache.derby.jdbc.ClientDriver");
connect_update = DriverManager.getConnection("jdbc:derby://localhost:1527/treedata2", "suraj", "suraj");
PreparedStatement updateQry = connect.prepareStatement("UPDATE student_details SET student_name='"+studDetailsTxtbxchange[0]+"',student_address='"+studDetailsTxtbxchange[1]+"',student_school='"+studDetailsTxtbxchange[2]+"' WHERE student_name='"+user_name+"' and student_address='"+user_add+"'and student_school='"+user_other+"'");
updateQry.executeUpdate();
JOptionPane.showMessageDialog(null,"Record Updated!","UPDATED",JOptionPane.OK_OPTION);
tree_generation.loadit();
loadit（）final还有一件事，尝试使用适当的，而不是使用绝对定位。使用适当的布局管理器可以使您的代码更易于维护，并且在不同的平台/外观上更易于移植。考虑简化您的代码，使其对我们来说是可运行的，但删除了所有数据库引用，删除了所有与问题无关的代码，以便隔离问题，如果问题仍然存在，允许我们在不需要数据库的情况下运行您的代码，在不检查大量无关代码的情况下检查您的代码，并希望允许我们找到解决方案。嗨，气垫船上满是鳗鱼，感谢您的检查。实际上，代码是可运行的。数据库文件也在那里，您只需将其复制粘贴到netbeans derby中即可。将java文件粘贴到新的项目文件夹中并运行。让我知道我是否应该移除它。@SurajB当然，移除不必要的东西。如果不创建数据库、添加公共集合等，代码将无法运行。。。这使得其他人很不愿意获取您的代码并执行它。代码太多，无法读取。Als，你应该考虑以下内容：1）不要默默地抓住一个例外（这是新手错误）2）正确缩进代码3）遵循java编码约定：类名以大写字母开头，包应该只包含小写字母，变量以小写字母开头…使用camel case而不是underscores@SurajB如果不修改外观或其任何属性，则不需要调用
tree.updateUI（）@Suraj：没有人要求你做出纪尧姆和我建议的改变，但通常你越容易让别人帮助你，你就越有机会得到快速的帮助。如果你得到了一个体面的解决方案而不做这些改变，那么很好，但如果没有，你仍然滞留，请考虑我们的建议。非常感谢你的输入Guillaume Polet。在可能的情况下，我会尝试删除静态文件，并设置一个布局管理器。至于刷新，你能指导我如何用我的代码刷新整个树吗？我知道这很昂贵，但这正是现在的需要。嗨，垃圾上帝，谢谢你关注我的问题。实际上，我访问了您提供的示例，但没有找到在哪里使用了重载。如果您能给我一个如何在JTree上实现它的指针，我将不胜感激。@SurajB：为我粗心的链接道歉；这个相关的使用了reload（）
。嗨，垃圾神，我确实访问了你的链接。在分析并尝试应用相同的原理之后，我注意到treeModel.reload（）正在进行刷新工作。我尝试了同样的方法{我已经编辑了代码，请参阅loadit（）函数}，但没有成功。Jtree不会刷新。有什么建议吗？Guillaume Polet我确实在loadit（）函数{i have edited it}中添加了treeModel.reload（），但它仍然不会用数据库中更改的值刷新
Class.forName("org.apache.derby.jdbc.ClientDriver");
connect_update = DriverManager.getConnection("jdbc:derby://localhost:1527/treedata2", "suraj", "suraj");
PreparedStatement updateQry = connect.prepareStatement("UPDATE student_details SET student_name='"+studDetailsTxtbxchange[0]+"',student_address='"+studDetailsTxtbxchange[1]+"',student_school='"+studDetailsTxtbxchange[2]+"' WHERE student_name='"+user_name+"' and student_address='"+user_add+"'and student_school='"+user_other+"'");
updateQry.executeUpdate();
JOptionPane.showMessageDialog(null,"Record Updated!","UPDATED",JOptionPane.OK_OPTION);
tree_generation.loadit();