嗨，我正在研究Java应用程序。我有一些问题。当我第一次运行app时没有任何问题。我想在选择教员时清除以前的部门和小组信息并加载新的结果。但是当我选择教员时我会遇到一些错误......我无法解决这个问题......请帮我解决一下......
以下是代码和错误。
import java.awt.EventQueue;
import javax.swing.JFrame;
import java.awt.BorderLayout;
import java.io.BufferedReader;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import javax.swing.JPanel;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JComboBox;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.ListSelectionModel;
import net.miginfocom.swing.MigLayout;
import javax.swing.UIManager;
import javax.swing.border.LineBorder;
import javax.swing.table.DefaultTableModel;
import javax.swing.JPopupMenu;
import java.awt.Component;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JMenuItem;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class showStudentSection {
private String db;
private String db_user;
private String db_pass;
private JFrame frmStudents;
private JTable table;
private Lang lang = new Lang();
private Theme theme = new Theme();
private doSpecificOperations ops = new doSpecificOperations();
private getTables getTable = new getTables();
private JComboBox<String> comboGroup;
private JComboBox<String> comboDepartment;
private JComboBox<String> comboFaculty;
private ArrayList<Integer> groupID = new ArrayList<Integer>();
private ArrayList<Integer> depID = new ArrayList<Integer>();
private ArrayList<Integer> facultyID = new ArrayList<Integer>();
private Boolean first_time_fac = true;
private Boolean first_time_dep = true;
private Boolean first_time_grp = true;
public static void main(String[] args) {
try {
UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel");
} catch (Throwable e) {
e.printStackTrace();
}
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
showStudentSection window = new showStudentSection();
window.frmStudents.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public showStudentSection() {
initialize();
}
private void initialize() {
getDB();
frmStudents = new JFrame();
frmStudents.getContentPane().setBackground(theme.setColor(1));
frmStudents.setTitle("Students");
frmStudents.setBounds(100, 100, 909, 473);
frmStudents.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frmStudents.getContentPane().setLayout(new BorderLayout(0, 0));
JPanel upPanel = new JPanel();
upPanel.setBorder(new LineBorder(theme.setColor(3)));
upPanel.setBackground(theme.setColor(1));
frmStudents.getContentPane().add(upPanel, BorderLayout.NORTH);
JLabel lblFaculty = new JLabel("Faculty:");
lblFaculty.setBackground(theme.setColor(1));
lblFaculty.setForeground(theme.setColor(2));
upPanel.add(lblFaculty);
comboFaculty = new JComboBox<String>();
comboFaculty.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
if(first_time_fac==false){
LoadDepartments(facultyID.get(comboFaculty.getSelectedIndex()));
}
first_time_fac=false;
}
});
comboFaculty.setBackground(theme.setColor(1));
upPanel.add(comboFaculty);
JLabel lblDepartment = new JLabel("Department:");
lblDepartment.setBackground(theme.setColor(1));
lblDepartment.setForeground(theme.setColor(2));
upPanel.add(lblDepartment);
comboDepartment = new JComboBox<String>();
comboDepartment.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
if(first_time_dep==false){
LoadGroups(depID.get(comboDepartment.getSelectedIndex()));
}
first_time_dep=false;
}
});
comboDepartment.setBackground(theme.setColor(1));
upPanel.add(comboDepartment);
JLabel lblGroup = new JLabel("Group:");
lblGroup.setBackground(theme.setColor(1));
lblGroup.setForeground(theme.setColor(2));
upPanel.add(lblGroup);
comboGroup = new JComboBox<String>();
comboGroup.setBackground(theme.setColor(1));
upPanel.add(comboGroup);
JPanel downPanel = new JPanel();
downPanel.setBorder(new LineBorder(theme.setColor(3)));
downPanel.setBackground(theme.setColor(1));
frmStudents.getContentPane().add(downPanel, BorderLayout.SOUTH);
JButton btnClose = new JButton("Close");
btnClose.setBackground(theme.setColor(1));
btnClose.setForeground(theme.setColor(2));
downPanel.add(btnClose);
JPanel leftPanel = new JPanel();
leftPanel.setBackground(theme.setColor(1));
frmStudents.getContentPane().add(leftPanel, BorderLayout.WEST);
leftPanel.setLayout(new MigLayout("", "[]", "[][][][][][][]"));
JLabel lblStudentOperations = new JLabel("Student operations");
lblStudentOperations.setBackground(theme.setColor(1));
lblStudentOperations.setForeground(theme.setColor(2));
leftPanel.add(lblStudentOperations, "cell 0 0,growx");
JButton btnAddStudent = new JButton("Add student");
btnAddStudent.setBackground(theme.setColor(1));
btnAddStudent.setForeground(theme.setColor(2));
leftPanel.add(btnAddStudent, "cell 0 1,growx");
JButton btnDeleteStudent = new JButton("Delete student");
btnDeleteStudent.setBackground(theme.setColor(1));
btnDeleteStudent.setForeground(theme.setColor(2));
leftPanel.add(btnDeleteStudent, "cell 0 2,growx");
JButton btnEditStudent = new JButton("Edit student");
btnEditStudent.setBackground(theme.setColor(1));
btnEditStudent.setForeground(theme.setColor(2));
leftPanel.add(btnEditStudent, "cell 0 3,growx");
JLabel lblOperations = new JLabel("Other operations");
lblOperations.setBackground(theme.setColor(1));
lblOperations.setForeground(theme.setColor(2));
leftPanel.add(lblOperations, "cell 0 4,growx");
JButton btnFindStudent = new JButton("Find student");
btnFindStudent.setBackground(theme.setColor(1));
btnFindStudent.setForeground(theme.setColor(2));
leftPanel.add(btnFindStudent, "cell 0 5,growx");
JButton btnSaveTable = new JButton("Save table (xls)");
btnSaveTable.setBackground(theme.setColor(1));
btnSaveTable.setForeground(theme.setColor(2));
leftPanel.add(btnSaveTable, "cell 0 6,growx");
JPanel center = new JPanel();
frmStudents.getContentPane().add(center, BorderLayout.CENTER);
center.setLayout(new BorderLayout(0, 0));
JScrollPane scrollPane = new JScrollPane();
center.add(scrollPane, BorderLayout.CENTER);
table = new JTable();
table.setSelectionBackground(theme.setColor(5));
table.setShowVerticalLines(true);
table.setShowHorizontalLines(true);
table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
scrollPane.setViewportView(table);
JPopupMenu popupMenu = new JPopupMenu();
addPopup(table, popupMenu);
JMenuItem mntmSeeStudentInformation = new JMenuItem("See student information");
popupMenu.add(mntmSeeStudentInformation);
LoadFaculties();
LoadDepartments(facultyID.get(comboFaculty.getSelectedIndex()));
LoadGroups(depID.get(comboDepartment.getSelectedIndex()));
LoadStudents("WHERE facultyID="+facultyID.get(comboFaculty.getSelectedIndex())+" AND depID="+depID.get(comboDepartment.getSelectedIndex()) + " AND groupID="+groupID.get(comboGroup.getSelectedIndex()));
}
private void LoadStudents(String query)
{
DefaultTableModel model = new DefaultTableModel(){
private static final long serialVersionUID = 1L;
@Override
public boolean isCellEditable(int row, int column)
{
return false;
}
};
try {
Class.forName("com.mysql.jdbc.Driver");
Connection elaqe = DriverManager.getConnection(db,db_user,db_pass);
Statement sorgu = elaqe.createStatement();
ResultSet netice = sorgu.executeQuery("SELECT * FROM students " + query);
int c_count = netice.getMetaData().getColumnCount();
model.addColumn(lang.translate("student_no"));
model.addColumn(lang.translate("name_surname"));
model.addColumn(lang.translate("sex"));
model.addColumn(lang.translate("birthday"));
model.addColumn(lang.translate("birth_place"));
model.addColumn(lang.translate("admission_year"));
model.addColumn(lang.translate("profession"));
model.addColumn(lang.translate("phone"));
model.addColumn(lang.translate("e_mail"));
model.addColumn(lang.translate("education_status"));
while(netice.next())
{
Object[] row = new Object[c_count];
row[0] = netice.getString("studentNO");
row[1] = netice.getString("name");
row[2] = netice.getString("gender");
row[3] = netice.getString("date_birth");
row[4] = netice.getString("place_birth");
row[5] = netice.getString("admission_date");
row[6] = getTable.getStudentProfessionText(netice.getString("profession"));
row[7] = netice.getString("phone");
row[8] = netice.getString("e_mail");
row[9] = getTable.getStudentStatusText(netice.getString("education_status"));
model.addRow(row);
}
elaqe.close();
sorgu.close();
table.setModel(model);
} catch (Exception e) {
ops.createInfoMessage(lang.translate("error"),lang.translate("db_error")+" (" + e.toString().substring(0, 40) + ")");
}
}
private void LoadFaculties()
{
try {
Class.forName("com.mysql.jdbc.Driver");
Connection elaqe = DriverManager.getConnection(db,db_user,db_pass);
Statement sorgu = elaqe.createStatement();
ResultSet netice = sorgu.executeQuery("SELECT * FROM faculties");
while(netice.next())
{
comboFaculty.addItem(netice.getString("name"));
facultyID.add(netice.getInt("facultyID"));
}
elaqe.close();
sorgu.close();
} catch (Exception e) {
ops.createInfoMessage(lang.translate("error"),lang.translate("db_error")+" (" + e.toString().substring(0, 40) + ")");
}
}
private void LoadDepartments(int facultyID)
{
comboDepartment.removeAllItems();
depID.clear();
try {
Class.forName("com.mysql.jdbc.Driver");
Connection elaqe = DriverManager.getConnection(db,db_user,db_pass);
Statement sorgu = elaqe.createStatement();
ResultSet netice = sorgu.executeQuery("SELECT * FROM department WHERE facultyID="+facultyID);
while(netice.next())
{
comboDepartment.addItem(netice.getString("name"));
depID.add(netice.getInt("depID"));
}
elaqe.close();
sorgu.close();
} catch (Exception e) {
ops.createInfoMessage(lang.translate("error"),lang.translate("db_error")+" (" + e.toString().substring(0, 40) + ")");
}
}
private void LoadGroups(int depID)
{
comboGroup.removeAllItems();
groupID.clear();
try {
Class.forName("com.mysql.jdbc.Driver");
Connection elaqe = DriverManager.getConnection(db,db_user,db_pass);
Statement sorgu = elaqe.createStatement();
ResultSet netice = sorgu.executeQuery("SELECT * FROM groups WHERE depID="+depID);
while(netice.next())
{
comboGroup.addItem(netice.getString("name"));
groupID.add(netice.getInt("groupID"));
}
elaqe.close();
sorgu.close();
} catch (Exception e) {
ops.createInfoMessage(lang.translate("error"),lang.translate("db_error")+" (" + e.toString().substring(0, 40) + ")");
}
}
private void getDB()
{
try {
BufferedReader bf = new BufferedReader(new FileReader(".\\mysql.db"));
db = ops.decodeText(bf.readLine());
db_user = ops.decodeText(bf.readLine());
db_pass = ops.decodeText(bf.readLine());
bf.close();
} catch (Exception e) {
ops.createInfoMessage(lang.translate("error"),lang.translate("cant_get_db_info")+" (" + e.toString().substring(0, 40) + ")");
}
}
private static void addPopup(Component component, final JPopupMenu popup) {
component.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
if (e.isPopupTrigger()) {
showMenu(e);
}
}
public void mouseReleased(MouseEvent e) {
if (e.isPopupTrigger()) {
showMenu(e);
}
}
private void showMenu(MouseEvent e) {
popup.show(e.getComponent(), e.getX(), e.getY());
}
});
}
}
和错误
Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -1
at java.util.ArrayList.elementData(Unknown Source)
at java.util.ArrayList.get(Unknown Source)
at showStudentSection$3.actionPerformed(showStudentSection.java:133)
at javax.swing.JComboBox.fireActionEvent(Unknown Source)
at javax.swing.JComboBox.contentsChanged(Unknown Source)
at javax.swing.JComboBox.intervalRemoved(Unknown Source)
at javax.swing.AbstractListModel.fireIntervalRemoved(Unknown Source)
at javax.swing.DefaultComboBoxModel.removeAllElements(Unknown Source)
at javax.swing.JComboBox.removeAllItems(Unknown Source)
at showStudentSection.LoadDepartments(showStudentSection.java:310)
at showStudentSection.access$4(showStudentSection.java:308)
at showStudentSection$2.actionPerformed(showStudentSection.java:112)
at javax.swing.JComboBox.fireActionEvent(Unknown Source)
at javax.swing.JComboBox.setSelectedItem(Unknown Source)
at javax.swing.JComboBox.setSelectedIndex(Unknown Source)
at javax.swing.plaf.basic.BasicComboPopup$Handler.mouseReleased(Unknown Source)
at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at javax.swing.plaf.basic.BasicComboPopup$1.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$400(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)**strong text**
答案 0 :(得分：3)
只需阅读堆栈跟踪...
在第310行清除comboBox时：
comboDepartment.removeAllItems();
您可以调用您组合的actionListener，然后在第133行调用
LoadGroups(depID.get(comboDepartment.getSelectedIndex()));
刚刚清除了组合，getSelectedIndex（）返回-1并且get失败。
结论：如果getSelectedIndex（）等于-1，则不加载组。