我已经为此苦苦挣扎了一段时间。我正在尝试使用所有者对象更新一个空的 JCombobox，只要通过单击按钮创建它，但我不断收到 nullpointerexception
package gui;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JMenuBar;
import javax.swing.JToolBar;
import javax.swing.JTabbedPane;
import javax.swing.JDesktopPane;
import javax.swing.border.TitledBorder;
import javax.swing.border.LineBorder;
import java.awt.Color;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.Insets;
import java.awt.Button;
import java.awt.Component;
import javax.swing.JLayeredPane;
import javax.swing.JTable;
import javax.swing.Box;
import javax.swing.JSplitPane;
import javax.swing.AbstractAction;
import java.awt.event.ActionEvent;
import javax.swing.Action;
import javax.swing.JInternalFrame;
import java.awt.event.*;
import controller.ForestOwnerCtr;
import model.OwnerCon;
import model.Owner;
import model.Tree;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.JList;
import javax.swing.JComboBox;
import java.awt.Choice;
import java.awt.Label;
import javax.swing.DefaultComboBoxModel;
public class ForestGui extends JFrame {
private static ForestOwnerCtr FOCtr;
private JPanel contentPane;
private JTextField txtOwnerName;
private JTextField txtOwnerAdress;
private JTextField txtOwnerPhone;
private JTextField txtName;
private JTextField txtLocation;
private JTextField txtArea;
private JTextField textField;
private JTextField textField_3;
private JTextField textField_4;
private JTextField txtAge;
private JComboBox<Owner> owner_select;
private ArrayList<Owner> test;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ForestGui frame = new ForestGui();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
FOCtr = new ForestOwnerCtr();
}
/**
* Create the frame.
*/
public ForestGui() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 946, 509);
JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
JButton btnCreate = new JButton("Create");
menuBar.add(btnCreate);
JButton btnSearch_1 = new JButton("Search");
menuBar.add(btnSearch_1);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JPanel panel_search_forest = new JPanel();
panel_search_forest.setBorder(new TitledBorder(new LineBorder(new Color(130, 135, 144)), "Seach forest", TitledBorder.LEADING, TitledBorder.TOP, null, null));
panel_search_forest.setToolTipText("tst");
panel_search_forest.setBounds(15, 11, 238, 238);
contentPane.add(panel_search_forest);
panel_search_forest.setLayout(null);
JLabel lblName_1 = new JLabel("Name");
lblName_1.setBounds(10, 28, 46, 14);
panel_search_forest.add(lblName_1);
txtName = new JTextField();
txtName.setColumns(10);
txtName.setBounds(92, 26, 119, 19);
panel_search_forest.add(txtName);
JLabel lblLocation = new JLabel("Location");
lblLocation.setBounds(10, 56, 58, 14);
panel_search_forest.add(lblLocation);
JLabel lblArea = new JLabel("Area");
lblArea.setBounds(10, 81, 46, 14);
panel_search_forest.add(lblArea);
txtLocation = new JTextField();
txtLocation.setColumns(10);
txtLocation.setBounds(92, 54, 119, 19);
panel_search_forest.add(txtLocation);
txtArea = new JTextField();
txtArea.setColumns(10);
txtArea.setBounds(92, 79, 119, 19);
panel_search_forest.add(txtArea);
JLabel lblAge = new JLabel("Age");
lblAge.setBounds(10, 106, 46, 14);
panel_search_forest.add(lblAge);
txtAge = new JTextField();
txtAge.setColumns(10);
txtAge.setBounds(92, 107, 119, 19);
panel_search_forest.add(txtAge);
JButton CreateForest = new JButton("New forest");
CreateForest.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
createForest();
}
});
CreateForest.setBounds(109, 204, 119, 23);
panel_search_forest.add(CreateForest);
JLabel lblOwner = new JLabel("Owner");
lblOwner.setBounds(10, 131, 46, 14);
panel_search_forest.add(lblOwner);
Choice choice = new Choice();
choice.setBounds(92, 163, 119, 19);
panel_search_forest.add(choice);
JLabel lblTreeSorts = new JLabel("Tree sorts");
lblTreeSorts.setBounds(10, 163, 76, 20);
panel_search_forest.add(lblTreeSorts);
JComboBox<Owner> owner_select = new JComboBox<Owner>();
owner_select.setModel(new DefaultComboBoxModel(FOCtr.getOwners().toArray()));
owner_select.setBounds(90, 137, 121, 20);
panel_search_forest.add(owner_select);
JPanel searc_owner = new JPanel();
searc_owner.setToolTipText("tst");
searc_owner.setBorder(new TitledBorder(new LineBorder(new Color(130, 135, 144)), "Seach owner", TitledBorder.LEADING, TitledBorder.TOP, null, null));
searc_owner.setBounds(263, 11, 250, 196);
contentPane.add(searc_owner);
searc_owner.setLayout(null);
JLabel lblName = new JLabel("Name");
lblName.setBounds(10, 22, 46, 14);
searc_owner.add(lblName);
JLabel lblAdress = new JLabel("Adress");
lblAdress.setBounds(10, 47, 46, 14);
searc_owner.add(lblAdress);
JLabel lblPhoneNumber = new JLabel("Phone number");
lblPhoneNumber.setBounds(10, 77, 83, 14);
searc_owner.add(lblPhoneNumber);
txtOwnerName = new JTextField();
txtOwnerName.setBounds(111, 20, 119, 17);
searc_owner.add(txtOwnerName);
txtOwnerName.setColumns(10);
txtOwnerAdress = new JTextField();
txtOwnerAdress.setColumns(10);
txtOwnerAdress.setBounds(111, 45, 119, 17);
searc_owner.add(txtOwnerAdress);
txtOwnerPhone = new JTextField();
txtOwnerPhone.setColumns(10);
txtOwnerPhone.setBounds(111, 75, 119, 17);
searc_owner.add(txtOwnerPhone);
JButton btnSearch = new JButton("New Owner");
btnSearch.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent E) {
createOwner();
}
});
btnSearch.setBounds(141, 162, 89, 23);
searc_owner.add(btnSearch);
JPanel panel = new JPanel();
panel.setLayout(null);
panel.setToolTipText("tst");
panel.setBorder(new TitledBorder(new LineBorder(new Color(130, 135, 144)), "Seach forest", TitledBorder.LEADING, TitledBorder.TOP, null, null));
panel.setBounds(585, 171, 238, 196);
contentPane.add(panel);
JLabel label = new JLabel("Name");
label.setBounds(10, 28, 46, 14);
panel.add(label);
textField = new JTextField();
textField.setColumns(10);
textField.setBounds(78, 25, 119, 17);
panel.add(textField);
JLabel label_1 = new JLabel("Location");
label_1.setBounds(10, 56, 58, 14);
panel.add(label_1);
JLabel label_2 = new JLabel("Area");
label_2.setBounds(10, 81, 46, 14);
panel.add(label_2);
textField_3 = new JTextField();
textField_3.setColumns(10);
textField_3.setBounds(78, 53, 119, 17);
panel.add(textField_3);
textField_4 = new JTextField();
textField_4.setColumns(10);
textField_4.setBounds(78, 78, 119, 17);
panel.add(textField_4);
JButton button_1 = new JButton("Search");
button_1.setBounds(139, 162, 89, 23);
panel.add(button_1);
}
private void createForest(){
String name = txtName.getText();
String location = txtLocation.getText();
int totalArea = Integer.parseInt(txtArea.getText());
int age = Integer.parseInt(txtAge.getText());
//Owner owner =
FOCtr.createForest(name, location, totalArea, age);
}
private void createOwner(){
String newName = txtOwnerName.getText();
String newAdress = txtOwnerAdress.getText();
String newPhone = txtOwnerPhone.getText();
Owner o = new Owner(newName, newAdress, newPhone);
test.add(o);
owner_select.addItem(o);
}
}
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at gui.ForestGui.createOwner(ForestGui.java:285)
at gui.ForestGui.access$1(ForestGui.java:278)
at gui.ForestGui$3.actionPerformed(ForestGui.java:211)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.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$200(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)