我正在使用swing中的jcombobox并从getSelectedIndex方法获取一些意外的输出。当我选择第一个JComboBox然后第二个组合框启用时，我正在使用一个方法getSelectedIndex（），它显示一些意外的输出。我的意思是它应该显示“0”，但它显示“0”然后显示“-1”然后是异常，然后最后显示“0”。我无法弄清楚异常的原因。我在这里只展示了部分代码，希望你们能帮到我......
public Tester() {
super("Utility for publish_date");
Container contentpane = getContentPane();
contentpane.setLayout(new BorderLayout());
try{
conn = new MyConn().getMyConnection();
s = conn.createStatement();
rs = s.executeQuery("select distinct state_name , state_code from state_master where state_code in (select statecode from pdf_detail) order by state_name");
statelist.add(0,"Select state");
while(rs.next())
{
statelist.add(rs.getString(1));
statecodelist.add(rs.getString(2));
}
System.out.println("the content of statelist"+ statelist);
System.out.println("the content of statecodelist"+statecodelist);
list_state = new String [statelist.size()];
statelist.toArray(list_state);
}catch(Exception e)
{
System.out.println(e);
log(e.getMessage());
}
combo = new JComboBox(list_state);
combo.setBounds(50, 50, 100, 20);
combo.addActionListener(this);
combo1 = new JComboBox();
combo1.addActionListener(this);
combo1.setEnabled(true);
combo1.setBounds(50, 100, 100, 20);
combo2 = new JComboBox();
combo2.addActionListener(this);
combo2.setEnabled(true);
combo2.setBounds(50, 100, 100, 20);
JPanel panel1 = new JPanel(new FlowLayout());
panel1.add(combo);
panel1.add(combo1);
panel1.add(combo2);
contentpane.add(panel1 , BorderLayout.NORTH);
label = new JLabel();
label.setText("Choose publish Date by selecting below.");
final SimpleDateFormat dateformater = new SimpleDateFormat("yyyy-MM-dd");
datepicker = new JXDatePicker();
datepicker.setFormats(dateformater);
datepicker.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
//label.setText(datepicker.getDate().toString());
System.out.println("new date is "+dateformater.format(datepicker.getDate()));
publish_date = dateformater.format(datepicker.getDate());
}
});
JPanel panel2 = new JPanel(new FlowLayout());
panel2.add(label);
panel2.add(datepicker);
contentpane.add(panel2 , BorderLayout.CENTER);
pbutton = new JButton("Submit");
pbutton.addActionListener(this);
JPanel panel3 = new JPanel();
panel3.add(pbutton);
contentpane.add(panel3 , BorderLayout.SOUTH);
setSize(600,150);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent a)
{
if (a.getSource() == combo) {
statename = (String)combo.getSelectedItem();
System.out.println("statename======="+statename);
q = combo.getSelectedIndex();
System.out.println("....q....."+q);
System.out.println(",,,,,,,,,,"+statecodelist.get(q-1));
try{
districtcodelist.clear();
ResultSet rs2 =s.executeQuery("select distinct district_name , district_code from district_master where state_code= '"+statecodelist.get(q-1)+"' AND district_code in (select districtcode from pdf_detail where statecode = '"+statecodelist.get(q-1)+"') order by district_name ");
//districtlist.add(0, "Select district");
while(rs2.next())
{
districtlist.add(rs2.getString(1));
districtcodelist.add(rs2.getString(2));
}
System.out.println("the content of districtlist"+ districtlist);
System.out.println("the content of districtcodelist"+districtcodelist);
list_district = new String [districtlist.size()];
districtlist.toArray(list_district);
}catch(Exception f)
{
f.printStackTrace();
System.out.println(f);
log(f.getMessage());
}
//combo1.setEnabled(true);
combo1.removeAllItems();
for (int i = 0; i < list_district.length; i++) {
combo1.removeItem(list_district[i]);
combo1.addItem(list_district[i]);
}
districtlist.clear();
}
else if (a.getSource() == combo1)
{
// System.out.println("combo1");
districtname = (String)combo1.getSelectedItem();
System.out.println("districtname========"+districtname);
w = combo1.getSelectedIndex();
if(w == -1)
{
System.out.println("hre is the prob");
System.out.println(combo1.getSelectedItem());
}
System.out.println(".....w...."+w);
System.out.println(combo1.getSelectedItem());
//System.out.println(",,,,,,,,,,"+districtcodelist.get(w));
try{
//tehsillist.add(0,"Select tehsil");
ResultSet rs3 = s.executeQuery("select distinct tehsil_name , tehsil_code from tehsil_master where state_code= '"+statecodelist.get(q-1)+"' AND district_code='"+districtcodelist.get(w)+"' AND tehsil_code in ( select tehsilcode from pdf_detail where statecode = '"+statecodelist.get(q-1)+"' AND districtcode = '"+districtcodelist.get(w)+"') order by tehsil_name");
while(rs3.next())
{
tehsillist.add(rs3.getString(1));
}
list_tehsil = new String [tehsillist.size()];
tehsillist.toArray(list_tehsil);
}catch(Exception g)
{
g.printStackTrace();
log(g.getMessage());
System.out.println(g);
}
//combo2.setEnabled(true);
combo2.removeAllItems();
for (int i = 0; i < list_tehsil.length; i++) {
combo2.removeItem(list_tehsil[i]);
combo2.addItem(list_tehsil[i]);
}
tehsillist.clear();
}
if(a.getSource() == pbutton){
tehsilname = (String)combo2.getSelectedItem();
e = combo2.getSelectedIndex();
System.out.println("....e....."+e);
System.out.println("....w....."+w);
if((String)combo.getSelectedItem()== "Select state" || (String)combo1.getSelectedItem()== "Select district" || (String)combo2.getSelectedItem()== "Select tehsil" || publish_date == null )
{
JOptionPane.showMessageDialog(this, "Select all four items first.");
}
else
{
int c = JOptionPane.showConfirmDialog(this,"Do you really want to continue?","update publish date?",JOptionPane.YES_NO_OPTION);
if(c==0)
{
log("State is "+statename+" \nDistrict is "+districtname+" \nTehsil is "+tehsilname);
try{
Properties pr =new Properties();
pr.load(new FileInputStream("config/config.properties"));
//String publish_date = pr.getProperty("publish_date");
ResultSet rs4 = s.executeQuery("select publish_date from pdf_detail where statecode = (select state_code from state_master where state_name = '"+statename+"') AND districtcode = (select district_code from district_master where district_name = '"+districtname+"') AND tehsilcode = (select tehsil_code from tehsil_master where tehsil_name = '"+tehsilname+"') ");
while(rs4.next())
{
testvalue = rs4.getString(1);
}
if(testvalue != null)
{
n = JOptionPane.showConfirmDialog(this,"Publish_date is already assigned to this tehsil. Do you want to update it?","update publish date?",JOptionPane.YES_NO_OPTION);
System.out.println("the value of n is "+n);
}
if(testvalue == null || n == 0)
{
JOptionPane.showMessageDialog(this, "Publish_date updated");
s.executeUpdate("Update pdf_detail set publish_date = '"+publish_date+"'where statecode=(select state_code from state_master where state_name='"+statename+"') AND districtcode=(select district_code from district_master where district_name='"+districtname+"') AND tehsilcode=(select tehsil_code from tehsil_master where tehsil_name='"+tehsilname+"')");
log("publish date of "+tehsilname+" is updated from ("+testvalue+") to ("+publish_date+")");
}
}catch(Exception e){
log(e.getMessage());
System.out.println(e);}
if(n==1)
{
JOptionPane.showMessageDialog(this, "Pulish_date updation canceled");
log("publish_date process canceled as it is already done");
}
JOptionPane.showMessageDialog(this, "Proces completed");
log("process completed at");
log("------------------------------------------------------------------------");
excelLog();
}
else{
setVisible(false);
(new Publish_Date()).setVisible(true);
}
}
}
}
public static void main(String args[]) {
log("process start time");
(new Tester()).setVisible(true);
}
}
输出：
....q.....1
.....w....0
....q.....1
.....w....-1
java.lang.ArrayIndexOutOfBoundsException: -1
at java.util.ArrayList.get(Unknown Source)
at com.Publish_Date.itemStateChanged(Publish_Date.java:215)
at javax.swing.JComboBox.fireItemStateChanged(Unknown Source)
at javax.swing.JComboBox.selectedItemChanged(Unknown Source)
at javax.swing.JComboBox.contentsChanged(Unknown Source)
at javax.swing.AbstractListModel.fireContentsChanged(Unknown Source)
at javax.swing.DefaultComboBoxModel.setSelectedItem(Unknown Source)
at javax.swing.DefaultComboBoxModel.removeElementAt(Unknown Source)
at javax.swing.DefaultComboBoxModel.removeElement(Unknown Source)
at javax.swing.JComboBox.removeItem(Unknown Source)
at com.Publish_Date.itemStateChanged(Publish_Date.java:190)
at javax.swing.JComboBox.fireItemStateChanged(Unknown Source)
at javax.swing.JComboBox.selectedItemChanged(Unknown Source)
at javax.swing.JComboBox.contentsChanged(Unknown Source)
at javax.swing.AbstractListModel.fireContentsChanged(Unknown Source)
at javax.swing.DefaultComboBoxModel.setSelectedItem(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$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$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)
java.lang.ArrayIndexOutOfBoundsException: -1
.....w....0
答案 0 :(得分：1)
当没有选择项目时，JComboBox的选定索引为-1。如果选中第二个复选框中的项目并更改了第一个复选框中的选项，则combo1.removeAllItems();将删除第二个复选框中的所有项目，这将导致复选框将其选择更改为-1并触发事件
您很可能会检测到-1值，只是忽略该事件或进行一些清理。
答案 1 :(得分：0)
尝试 ActionListener
JComboBox<String> jb = new JComboBox<String>();
jb.add("Vivek"):
jb.add("Vicky");
jb.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
System.out.println(jb.getSelectedIndex());
}
});