空布局......

Question

我对JComboBox和JTable提出了疑问。

在项目中，我有3个JComboBox和一个JTable，我希望每次从JComboBox中选择一个项目，从表格中放入一些来自数据库的数据，但是在我运行代码之后，我发出通知，只有当我从第一个JComboBox中选择一个项目时，我才首先绑定到JTable，数据可以从数据库中获得。

我的问题是：我只能将一个JComboBox绑定到JTable？

我对所有3 JComboBox使用相同的代码。

package tutorial;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.LayoutManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.swing.*;
import java.sql.*;
import net.proteanit.sql.DbUtils;

public class Lista extends javax.swing.JFrame implements ActionListener, Runnable {
Connection conn;
public Lista() {
    initComponents();
    this.setSize(800,400);
    this.setResizable(false);  
}
// creates the components                    
private void initComponents() {
    bindingGroup = new org.jdesktop.beansbinding.BindingGroup();
    tfSearch = new javax.swing.JTextField();
    bSearch = new javax.swing.JButton();
    lbAutor = new javax.swing.JLabel();
    cboxAutor = new javax.swing.JComboBox();
    cboxCategorie = new javax.swing.JComboBox();
    jScrollPane1 = new javax.swing.JScrollPane();
    jTable1 = new javax.swing.JTable();
    cboxLibrarie = new javax.swing.JComboBox();
    cbEditura = new javax.swing.JComboBox();
    lbCategorie = new javax.swing.JLabel();
    lbLibrarie = new javax.swing.JLabel();
    lbEditura = new javax.swing.JLabel();
    jLabel1 = new javax.swing.JLabel();
    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    getContentPane().setLayout(null);
    tfSearch.setFont(new java.awt.Font("Arial Black", 1, 18)); // NOI18N
    tfSearch.addKeyListener(new java.awt.event.KeyAdapter() {
        public void keyReleased(java.awt.event.KeyEvent evt) {
            tfSearchKeyReleased(evt);
        }
    });
    getContentPane().add(tfSearch);
    tfSearch.setBounds(60, 40, 200, 30);
    bSearch.setBackground(new java.awt.Color(255, 255, 255));
    bSearch.setFont(new java.awt.Font("Arial Black", 1, 14)); // NOI18N
    bSearch.setText("Search");
    bSearch.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            bSearchActionPerformed(evt);
        }
    });
    getContentPane().add(bSearch);
    bSearch.setBounds(270, 40, 90, 30);
    lbAutor.setFont(new java.awt.Font("Arial Black", 3, 18)); // NOI18N
    lbAutor.setForeground(new java.awt.Color(255, 255, 255));
    lbAutor.setText("Autor:");
    getContentPane().add(lbAutor);
    lbAutor.setBounds(440, 120, 100, 20);
    cboxAutor.setBackground(new java.awt.Color(255, 153, 51));
    cboxAutor.setFont(new java.awt.Font("Arial Black", 1, 14)); // NOI18N
    cboxAutor.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Cristie", "Bronte", "Tolkien", "Meyer", "Van Vogt", "Pavel", "Inoue", "Austen", "Bromte", "Eminescu" }));
    cboxAutor.addItemListener(new java.awt.event.ItemListener() {
        public void itemStateChanged(java.awt.event.ItemEvent evt) {
            cboxAutorItemStateChanged(evt);
        }
    });
    cboxAutor.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            cboxAutorActionPerformed(evt);
        }
    });
    getContentPane().add(cboxAutor);
    cboxAutor.setBounds(560, 120, 220, 30);
    cboxCategorie.setBackground(new java.awt.Color(255, 153, 51));
    cboxCategorie.setFont(new java.awt.Font("Arial Black", 1, 14)); // NOI18N
    cboxCategorie.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Literatura de Dragoste", "Literatura Fantastica", "Literatura Politista", "Literatura SF", "Literatura Psihologica" }));
    org.jdesktop.beansbinding.Binding binding = org.jdesktop.beansbinding.Bindings.createAutoBinding(org.jdesktop.beansbinding.AutoBinding.UpdateStrategy.READ_WRITE, jTable1, org.jdesktop.beansbinding.ELProperty.create("mesajjjjj"), cboxCategorie, org.jdesktop.beansbinding.BeanProperty.create("selectedItem"));
    bindingGroup.addBinding(binding);
    cboxCategorie.addItemListener(new java.awt.event.ItemListener() {
        public void itemStateChanged(java.awt.event.ItemEvent evt) {
            cboxCategorieItemStateChanged(evt);
        }
    });
    cboxCategorie.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            cboxCategorieActionPerformed(evt);
        }
    });
    getContentPane().add(cboxCategorie);
    cboxCategorie.setBounds(560, 240, 220, 30);
    jTable1.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(255, 204, 204), 1, true));
    jTable1.setFont(new java.awt.Font("Arial Black", 1, 14)); // NOI18N
    jTable1.setModel(new javax.swing.table.DefaultTableModel(
        new Object [][] {
        },
        new String [] {
        }
    ));
    jTable1.setDoubleBuffered(true);
    jScrollPane1.setViewportView(jTable1);
    getContentPane().add(jScrollPane1);
    jScrollPane1.setBounds(60, 100, 340, 230);
    cboxLibrarie.setBackground(new java.awt.Color(255, 153, 51));
    cboxLibrarie.setFont(new java.awt.Font("Arial Black", 1, 14)); // NOI18N
    cboxLibrarie.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Librarium", "Humanitas", "Carturesti", "Alpha", "Diverta", "Pheonix" }));
    cboxLibrarie.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            cboxLibrarieActionPerformed(evt);
        }
    });
    getContentPane().add(cboxLibrarie);
    cboxLibrarie.setBounds(560, 200, 220, 30);
    cbEditura.setBackground(new java.awt.Color(255, 153, 51));
    cbEditura.setFont(new java.awt.Font("Arial Black", 1, 14)); // NOI18N
    cbEditura.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Corint-Junior", "Gramar", "Albastra", "Teora", "Mega", "Mediamira", "U.T. PRESS" }));
    cbEditura.addItemListener(new java.awt.event.ItemListener() {
        public void itemStateChanged(java.awt.event.ItemEvent evt) {
            cbEdituraItemStateChanged(evt);
        }
    });
    cbEditura.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            cbEdituraActionPerformed(evt);
        }
    });
    getContentPane().add(cbEditura);
    cbEditura.setBounds(560, 160, 220, 30);
    lbCategorie.setFont(new java.awt.Font("Arial Black", 3, 18)); // NOI18N
    lbCategorie.setForeground(new java.awt.Color(255, 255, 255));
    lbCategorie.setText("Categorie:");
    getContentPane().add(lbCategorie);
    lbCategorie.setBounds(440, 240, 120, 30);
    lbLibrarie.setFont(new java.awt.Font("Arial Black", 3, 18)); // NOI18N
    lbLibrarie.setForeground(new java.awt.Color(255, 255, 255));
    lbLibrarie.setText("Librarie:");
    getContentPane().add(lbLibrarie);
    lbLibrarie.setBounds(440, 200, 120, 30);
    lbEditura.setFont(new java.awt.Font("Arial Black", 3, 18)); // NOI18N
    lbEditura.setForeground(new java.awt.Color(255, 255, 255));
    lbEditura.setText("Editura:");
    getContentPane().add(lbEditura);
    lbEditura.setBounds(440, 160, 130, 30);
    jLabel1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/img/lis.jpg"))); // NOI18N
    getContentPane().add(jLabel1);
    jLabel1.setBounds(0, 0, 790, 370);
    bindingGroup.bind();
    pack();
}// </editor-fold> 
//end initComponents


private void cboxLibrarieItemStateChanged(java.awt.event.ActionEvent evt) {                                             

    try{
        Class.forName("com.mysql.jdbc.Driver");
        String url="jdbc:mysql://localhost/proiectibd";
        conn =DriverManager.getConnection(url, "root", "");
        String sql;
        sql = "select Titlul_cartii,Data_publicatie,Pret from carte,librarie,arhiva where librarie.idLibrarie=arhiva.librarie_idLibrarie and carte.idCarte=arhiva.Carte_idCarte and nume_librarie=?";
        PreparedStatement ps;
        ps = conn.prepareStatement(sql);
        ps.setString(1,(String)cboxAutor.getSelectedItem());
        ResultSet rs=ps.executeQuery();
        jTable1.setModel(DbUtils.resultSetToTableModel (rs));
    }
    catch(Exception e){
        //JOptionPane.showMessageDialog(null,e);
    }
}                                            

//only this JComboBox works
private void cboxAutorItemStateChanged(java.awt.event.ItemEvent evt) {    
    try{
        Class.forName("com.mysql.jdbc.Driver");
        String url="jdbc:mysql://localhost/proiectibd";
        conn =DriverManager.getConnection(url, "root", "");
        String sql;
        sql = "select Titlul_cartii,Data_publicatie,Pret from carte,autor where carte.autor_idautor=autor.idAutor and Nume_Autor=?";
        PreparedStatement ps;
        ps = conn.prepareStatement(sql);
        ps.setString(1,cboxAutor.getSelectedItem().toString());
        ResultSet rs=ps.executeQuery();
        jTable1.setModel(DbUtils.resultSetToTableModel (rs));
    }
    catch(Exception e){
        //JOptionPane.showMessageDialog(null,e);
    }
}                   

private void cbEdituraItemStateChanged(java.awt.event.ItemEvent evt) {                                           
    try{
        Class.forName("com.mysql.jdbc.Driver");
        String url="jdbc:mysql://localhost/proiectibd";
        conn4 =DriverManager.getConnection(url, "root", "");
        String sql;
        sql = "select Titlul_cartii,Data_publicatie,Pret from carte,editura,contact where editura.ideditura=contact.editura_ideditura and carte.idCarte=contact.Carte_idCarte and nume_editura=?";
        PreparedStatement ps;
        ps = conn4.prepareStatement(sql);
        ps.setString(1,cboxAutor.getSelectedItem().toString());
        ResultSet rs=ps.executeQuery();
        jTable1.setModel(DbUtils.resultSetToTableModel (rs));
    }
    catch(Exception e){
        //JOptionPane.showMessageDialog(null,e);
    }
}                                          

private void cboxCategorieItemStateChanged(java.awt.event.ItemEvent evt) {                                               
    try{
        Class.forName("com.mysql.jdbc.Driver");
        String url="jdbc:mysql://localhost/proiectibd";
        conn =DriverManager.getConnection(url, "root", "");
        String sql;
        sql = "select Titlul_cartii,Data_publicatie,Pret from carte,categorii where carte.Categorii_idCategorii=categorii.idCategorii and Nume_categorie=?";
        PreparedStatement ps;
        ps = conn.prepareStatement(sql);
        ps.setString(1,cboxAutor.getSelectedItem().toString());
        ResultSet rs=ps.executeQuery();
        jTable1.setModel(DbUtils.resultSetToTableModel (rs));

    }

    catch(Exception e){
        //JOptionPane.showMessageDialog(null,e);
    }
}  

// Variables declaration - do not modify                     
private javax.swing.JButton bSearch;
private javax.swing.JComboBox cbEditura;
private javax.swing.JComboBox cboxAutor;
private javax.swing.JComboBox cboxCategorie;
private javax.swing.JComboBox cboxLibrarie;
private javax.swing.JLabel jLabel1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTable jTable1;
private javax.swing.JLabel lbAutor;
private javax.swing.JLabel lbCategorie;
private javax.swing.JLabel lbEditura;
private javax.swing.JLabel lbLibrarie;
private javax.swing.JTextField tfSearch;
private org.jdesktop.beansbinding.BindingGroup bindingGroup;
// End of variables declaration                   

@Override
public void actionPerformed(ActionEvent e) {
    //throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}
@Override
public void run() {
    //throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}
}

Answer 1

好的，让我们尝试系统地完成这个......

空布局......

避免使用null布局，像素完美布局是现代ui设计中的一种幻觉。影响组件个体大小的因素太多，您无法控制。 Swing旨在与布局管理器一起工作，放弃这些将导致问题和问题的终结，您将花费越来越多的时间来纠正

文本组件上的

`KeyListener` ...

将KeyListener放在文本组件上绝不是一个很好的理由。如果您想知道字段何时更新，请改用DocumentListener;如果要修改/过滤用户输入字段的内容，请使用DocumentFilter;如果您想知道用户何时按下 Enter 键，请使用ActionListener。

您当前的方法也非常不健康，每次发布密钥时尝试执行新请求都可能导致程序在发出请求时冻结或断断续续，也会执行不必要的请求。

相反，使用DocumentListener的组合来检测字段的更改，并使用javax.swing.Timer在更新之间注入一个小延迟，每次通知DocumentListener时重新启动计时器变化一旦计时器实际触发，那么您应该执行请求。

Combobox更新......

您似乎已复制并粘贴了代码，因为在cboxLibrarieItemStateChanged，cbEdituraItemStateChanged和cboxCategorieItemStateChanged方法中，您使用的是cboxAutor中的值。

ps.setString(1,cboxAutor.getSelectedItem().toString());

您需要为要搜索的字段使用正确的组合框...

资源管理

您没有很好地管理资源，打开连接和其他数据库资源，这可能会降低性能...

从Java 7开始，它变得非常容易管理......

try{
    Class.forName("com.mysql.jdbc.Driver");
    String url="jdbc:mysql://localhost/proiectibd";
    try (Connection conn = DriverManager.getConnection(url, "root", "")) {
        String sql = "select Titlul_cartii,Data_publicatie,Pret from carte,autor where carte.autor_idautor=autor.idAutor and Nume_Autor=?";
        try (PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setString(1,cboxAutor.getSelectedItem().toString());
            try (ResultSet rs=ps.executeQuery()) {
                jTable1.setModel(DbUtils.resultSetToTableModel (rs));
            }
        }
    }
} catch(SQLException e){
    e.printStackTrace();// At the very least...
    //JOptionPane.showMessageDialog(null,e);
}

有关详细信息，请参阅The try-with-resources Statement。

更多与一个JTable相关的Jcombo盒子

1 个答案:

空布局......

`KeyListener` ...

Combobox更新......

资源管理

更多与一个JTable相关的Jcombo盒子

1 个答案:

空布局......

KeyListener ...

Combobox更新......

资源管理

`KeyListener` ...