I keep receiving the error:
Exception in thread "main" java.lang.IllegalArgumentException: adding a window to a container
at java.awt.Container.checkNotAWindow(Container.java:483)
at java.awt.Container.addImpl(Container.java:1084)
at java.awt.Container.add(Container.java:966)
at Lab2.EmployeeGUI.main(EmployeeGUI.java:28)
Can someone please help me and tell me what I'm doing wrong? I am beginner programmer.
package Lab2;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
/**
*
* @author Jim Doyle
*/
public class EmployeeGUI extends JFrame implements ActionListener {
JTextField fName, mName, lName, phone, sal, years;
JComboBox boxTitle, boxDept;
DefaultListModel lstdefault;
JList project;
DbWork dbw = new DbWork("Lab2");
DbWork Title = new DbWork("Lab2");
DbWork Dept = new DbWork("Lab2");
DbWork Prjs = new DbWork("Lab2");
DbWork PrjList = new DbWork("Lab2");
public static void main(String[] args) {
EmployeeGUI app = new EmployeeGUI();
JFrame frame = new JFrame("Employee Interface by Jim Doyle");
frame.getContentPane().add(app, BorderLayout.CENTER);
frame.setSize(300, 300);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public EmployeeGUI() {
JPanel labels = new JPanel();
labels.setLayout(new GridLayout(8,1));
labels.add(new JLabel("First Name"));
labels.add(new JLabel("MI"));
labels.add(new JLabel("Last Name"));
labels.add(new JLabel("Title"));
labels.add(new JLabel("Telephone"));
labels.add(new JLabel("Salary"));
labels.add(new JLabel("Department"));
labels.add(new JLabel("Years in Service"));
getContentPane().add(labels, BorderLayout.WEST);
JPanel fields = new JPanel();
fields.setLayout(new GridLayout(8,1));
fName = new JTextField(15);
mName = new JTextField(15);
lName = new JTextField(15);
phone = new JTextField(15);
sal = new JTextField(15);
years = new JTextField(15);
boxTitle = new JComboBox();
boxDept = new JComboBox();
fields.add(fName);
fields.add(mName);
fields.add(lName);
fields.add(boxTitle);
fields.add(phone);
fields.add(sal);
fields.add(years);
getContentPane().add(fields, BorderLayout.CENTER);
JPanel prjinfo = new JPanel();
prjinfo.setLayout(new GridLayout(1,2));
prjinfo.add(new JLabel("Project Description"));
project = new JList();
lstdefault = new DefaultListModel();
// add items to title combo box
while(Title.nextRecord()) {
String txtTit = Title.getField(1);
if(txtTit!=null) {
boxTitle.addItem(Title.getField(1));
}
}
// add items to department combo box
while(Dept.nextRecord()) {
String txtDept = Dept.getField(2);
if(txtDept!=null) {
boxDept.addItem(Dept.getField(2));
}
}
while(PrjList.nextRecord()) {
lstdefault.addElement(PrjList.getField(1));
}
project = new JList(lstdefault);
project.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
prjinfo.add(project);
getContentPane().add(prjinfo, BorderLayout.SOUTH);
}
public void actionPerformed(ActionEvent e) {
String button = e.getActionCommand();
if(button == "First") {
if(dbw.firstRecord()) {
Execute();
}
}
else if(button == "Next") {
if(dbw.nextRecord()) {
Execute();
}
}
else if(button == "Save") {
String sql = "UPDATE FirstName, MiddleName, LastName, WorkPhone, Salary, YearsInService FROM Employee;";
dbw.processQuery(sql);
}
}
private void action() {
boxTitle.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JComboBox b = (JComboBox)e.getSource();
String ntitle = (String)b.getSelectedItem();
updateTitle(ntitle);
}
});
}
private void Execute() {
fName.setText(dbw.getField(1));
mName.setText(dbw.getField(2));
lName.setText(dbw.getField(3));
phone.setText(dbw.getField(5));
sal.setText(dbw.getField(6));
years.setText(dbw.getField(8));
String ftext = dbw.getField(4);
int dx = TitleList(ftext);
boxTitle.setSelectedIndex(dx);
String dtext = dbw.getField(7);
int dx2 = DeptList(dtext);
boxDept.setSelectedIndex(dx2);
action();
}
int TitleList(String title) {
int dx = 0;
for(int z=0; z<boxTitle.getItemCount(); z++) {
if(title.equals(boxTitle.getItemAt(z))) {
dx = z;
}
}
return dx;
}
int DeptList(String dept) {
int dx = 0;
for(int z=0; z<boxDept.getItemCount(); z++) {
if(dept.equals(boxDept.getItemAt(z))) {
dx = z;
}
}
return dx;
}
private void updateTitle(String title) {
}
}
EmployeeGUI extends from JFrame, but in your main method, you are creating a new JFrame and are trying to add an instance of EmployeeGUI to it.
Change EmployeeGUI so it extends from JPanel instead
Here:
frame.getContentPane().add(app, BorderLayout.CENTER);
you're trying to add a JFrame to a JFrame which makes no sense.
Why not instead just try to display app rather than add it to a JFrame. Or even better, not have EmployeeGUI extend JFrame.
You can't add a JFrame to another JFrame. But you can add a JPanel to a JFrame, in other words change EmployeeGUI to make it extends JPanel.
来源：https://stackoverflow.com/questions/16879703/java-error-illegalargumentexception-adding-a-window-to-a-container