我是J2ME的新手。我试图在ListItem的选择上从一个MIDlet页面导航到另一个页面。但我收到以下错误消息。
Installing suite from: file:///C:/Users/mohit/Documents/NetBeansProjects/MobileApp1/dist/nbrun8756732879038612272/MobileApp1.jad
6370272 - ERROR - AMS - 2 - Installation failed:com.sun.midp.midletsuite.MIDletSuiteLockedException
com.sun.midp.midletsuite.MIDletSuiteLockedException
at com.sun.midp.midletsuite.MIDletSuiteImpl.lockMIDletSuite(), bci=0
at com.sun.midp.midletsuite.MIDletSuiteStorage.getMIDletSuite(), bci=12
at com.sun.midp.installer.Installer.checkPreviousVersion(), bci=60
at com.sun.midp.installer.Installer.installStep2(), bci=10
at com.sun.midp.installer.Installer.performInstall(), bci=132
at com.sun.midp.installer.Installer.resumeInstallation(), bci=7
at com.sun.midp.installer.MidpInstaller$StartAction.run(), bci=10
at com.sun.j2me.security.AccessController.doPrivileged(), bci=12
at com.sun.midp.installer.MidpInstaller$InstallThread.run(), bci=9
at java.lang.Thread.run(Thread.java:721)
TRACE: <at java.lang.NullPointerException: 0>, Exception caught in Display class
java.lang.NullPointerException: 0
- mobileapp1.VisualMIDlet.commandAction(VisualMIDlet.java:180)
at javax.microedition.lcdui.Display$ChameleonTunnel.callScreenListener(), bci=39
at com.sun.midp.chameleon.layers.SoftButtonLayer.processCommand(), bci=62
at com.sun.midp.chameleon.layers.SoftButtonLayer.soft2(), bci=119
at com.sun.midp.chameleon.layers.SoftButtonLayer.keyInput(), bci=102
at com.sun.midp.chameleon.CWindow.keyInput(), bci=30
at javax.microedition.lcdui.Display$DisplayEventConsumerImpl.handleKeyEvent(), bci=43
at com.sun.midp.lcdui.DisplayEventListener.process(), bci=252
at com.sun.midp.events.EventQueue.run(), bci=130
at java.lang.Thread.run(Thread.java:721)
我不知道如何处理这一个。有人可以帮帮我吗？
//VisualMIDlet.java
package mobileapp1;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import org.netbeans.microedition.lcdui.LoginScreen;
public class VisualMIDlet extends MIDlet implements CommandListener {
private boolean midletPaused = false;
private java.util.Hashtable __previousDisplayables = new java.util.Hashtable();
private LoginScreen loginScreen;
private Form FallSem_Home;
private ChoiceGroup choiceGroup;
private List stud_homelist;
private Form WinterSem_Home;
private Command exit_StudList;
private Command exitCommand1;
private Command exitCommand2;
private Command backCommand;
private Command ok_StudList;
private Command okCommand;
private List menu = null;
private Display display;
Fall_Sem fall_sem;
public VisualMIDlet() {
//fall_sem = new Fall_Sem();
}
private void switchToPreviousDisplayable() {
Displayable __currentDisplayable = getDisplay().getCurrent();
if (__currentDisplayable != null) {
Displayable __nextDisplayable = (Displayable) __previousDisplayables.get(__currentDisplayable);
if (__nextDisplayable != null) {
switchDisplayable(null, __nextDisplayable);
}
}
}
private void initialize() {
// write pre-initialize user code here
// write post-initialize user code here
}
public void startMIDlet() {
// write pre-action user code here
switchDisplayable(null, getLoginScreen());
// write post-action user code here
}
public void resumeMIDlet() {
// write pre-action user code here
// write post-action user code here
}
public void switchDisplayable(Alert alert, Displayable nextDisplayable) {
// write pre-switch user code here
Display display = getDisplay();
Displayable __currentDisplayable = display.getCurrent();
if (__currentDisplayable != null && nextDisplayable != null) {
__previousDisplayables.put(nextDisplayable, __currentDisplayable);
}
if (alert == null) {
display.setCurrent(nextDisplayable);
} else {
display.setCurrent(alert, nextDisplayable);
}
// write post-switch user code here
}
public void commandAction(Command command, Displayable displayable) {
// write pre-action user code here
if (displayable == FallSem_Home) {
if (command == backCommand) {
// write pre-action user code here
// write post-action user code here
} else if (command == exit_StudList) {
// write pre-action user code here
//notifyDestroyed();
// write post-action user code here
} else if (command == okCommand) {
// write pre-action user code here
// write post-action user code here
}
} else if (displayable == WinterSem_Home) {
if (command == backCommand) {
// write pre-action user code here
switchToPreviousDisplayable();
// write post-action user code here
} else if (command == exitCommand2) {
// write pre-action user code here
// write post-action user code here
}
} else if (displayable == loginScreen) {
if (command == LoginScreen.LOGIN_COMMAND) {
// write pre-action user code here
if(loginScreen.getUsername().equals("mohit") && loginScreen.getPassword().equals("abhi")){
switchDisplayable(null, getStud_homelist());
// write post-action user code here
}
}
} else if (displayable == stud_homelist) {
if (command == List.SELECT_COMMAND) {
// write pre-action user code here
stud_homelistAction();
// write post-action user code here
} else if (command == exit_StudList) {
// write pre-action user code here
exitMIDlet();
// write post-action user code here
} **else if (command == ok_StudList) {
// write pre-action user code here
List options = (List) display.getCurrent();
switch(options.getSelectedIndex()){
case 0:
displayable = fall_sem.getForm();
switchDisplayable(null, displayable);
//display.setCurrent(fall_sem.getForm());
}
// write post-action user code here
}**
}
// write post-action user code here
}
public LoginScreen getLoginScreen() {
if (loginScreen == null) {
// write pre-init user code here
loginScreen = new LoginScreen(getDisplay());
loginScreen.setLabelTexts("Username", "Password");
loginScreen.setTitle("loginScreen");
loginScreen.addCommand(LoginScreen.LOGIN_COMMAND);
loginScreen.setCommandListener(this);
loginScreen.setFullScreenMode(true);
loginScreen.setBGColor(-3355444);
loginScreen.setFGColor(0);
loginScreen.setPassword("");
loginScreen.setUsername("");
loginScreen.setUseLoginButton(true);
loginScreen.setLoginButtonText("Login");
// write post-init user code here
}
return loginScreen;
}
public Form getFallSem_Home() {
if (FallSem_Home == null) {
// write pre-init user code here
FallSem_Home = new Form("form", new Item[]{getChoiceGroup()});
FallSem_Home.addCommand(getExit_StudList());
FallSem_Home.addCommand(getBackCommand());
FallSem_Home.addCommand(getOkCommand());
FallSem_Home.setCommandListener(this);
// write post-init user code here
}
return FallSem_Home;
}
public Command getExit_StudList() {
if (exit_StudList == null) {
// write pre-init user code here
exit_StudList = new Command("Exit", Command.EXIT, 0);
// write post-init user code here
}
return exit_StudList;
}
public ChoiceGroup getChoiceGroup() {
if (choiceGroup == null) {
// write pre-init user code here
choiceGroup = new ChoiceGroup("choices", Choice.EXCLUSIVE);
choiceGroup.append("Time Table", null);
choiceGroup.append("Exam Schedule", null);
choiceGroup.append("Marks", null);
choiceGroup.setFitPolicy(Choice.TEXT_WRAP_DEFAULT);
choiceGroup.setSelectedFlags(new boolean[]{false, false, false});
// write post-init user code here
}
return choiceGroup;
}
public List getStud_homelist() {
if (stud_homelist == null) {
// write pre-init user code here
stud_homelist = new List("list", Choice.IMPLICIT);
stud_homelist.append("Fall Sem 2012-13", null);
stud_homelist.append("Winter Sem 2012-13", null);
stud_homelist.append("Add / Drop", null);
stud_homelist.addCommand(getExit_StudList());
stud_homelist.addCommand(getOk_StudList());
stud_homelist.setCommandListener(this);
stud_homelist.setSelectedFlags(new boolean[]{false, false, false});
// write post-init user code here
}
return stud_homelist;
}
public void stud_homelistAction() {
// enter pre-action user code here
String __selectedString = getStud_homelist().getString(getStud_homelist().getSelectedIndex());
if (__selectedString != null) {
if (__selectedString.equals("Fall Sem 2012-13")) {
// write pre-action user code here
// write post-action user code here
} else if (__selectedString.equals("Winter Sem 2012-13")) {
// write pre-action user code here
// write post-action user code here
} else if (__selectedString.equals("Add / Drop")) {
// write pre-action user code here
// write post-action user code here
}
}
// enter post-action user code here
}
public Form getWinterSem_Home() {
if (WinterSem_Home == null) {
// write pre-init user code here
WinterSem_Home = new Form("form");
WinterSem_Home.addCommand(getBackCommand());
WinterSem_Home.addCommand(getExitCommand2());
WinterSem_Home.setCommandListener(this);
// write post-init user code here
}
return WinterSem_Home;
}
public Command getExitCommand1() {
if (exitCommand1 == null) {
// write pre-init user code here
exitCommand1 = new Command("Exit", Command.EXIT, 0);
// write post-init user code here
}
return exitCommand1;
}
public Command getBackCommand() {
if (backCommand == null) {
// write pre-init user code here
backCommand = new Command("Back", Command.BACK, 0);
// write post-init user code here
}
return backCommand;
}
public Command getExitCommand2() {
if (exitCommand2 == null) {
// write pre-init user code here
exitCommand2 = new Command("Exit", Command.EXIT, 0);
// write post-init user code here
}
return exitCommand2;
}
public Command getOkCommand() {
if (okCommand == null) {
// write pre-init user code here
okCommand = new Command("Ok", Command.OK, 0);
// write post-init user code here
}
return okCommand;
}
public Command getOk_StudList() {
if (ok_StudList == null) {
// write pre-init user code here
ok_StudList = new Command("Ok", Command.OK, 0);
// write post-init user code here
}
return ok_StudList;
}
public Display getDisplay() {
return Display.getDisplay(this);
}
public void exitMIDlet() {
switchDisplayable(null, null);
destroyApp(true);
notifyDestroyed();
}
public void startApp() {
if (midletPaused) {
resumeMIDlet();
} else {
initialize();
startMIDlet();
}
midletPaused = false;
}
public void pauseApp() {
midletPaused = true;
}
public void destroyApp(boolean unconditional) {
notifyDestroyed();
}
}
//Fall_Sem.java
package mobileapp1;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import org.netbeans.microedition.lcdui.LoginScreen;
import org.netbeans.microedition.lcdui.SimpleTableModel;
import org.netbeans.microedition.lcdui.TableItem;
public class Fall_Sem extends MIDlet implements CommandListener {
private boolean midletPaused = false;
private Display display;
private Form form;
private ChoiceGroup choiceGroup;
private Form form1;
private TableItem tableItem;
private Command backCommand;
private Command okCommand;
private Command exitCommand;
private Command exitCommand1;
private Command backCommand1;
private SimpleTableModel simpleTableModel;
public Fall_Sem() {
System.out.println("Fall Sem");
}
private void initialize() {
// write pre-initialize user code here
// write post-initialize user code here
}
public void startMIDlet() {
// write pre-action user code here
switchDisplayable(null, getForm());
// write post-action user code here
}
public void resumeMIDlet() {
// write pre-action user code here
// write post-action user code here
}
public void switchDisplayable(Alert alert, Displayable nextDisplayable) {
// write pre-switch user code here
Display display = getDisplay();
if (alert == null) {
display.setCurrent(nextDisplayable);
} else {
display.setCurrent(alert, nextDisplayable);
}
// write post-switch user code here
}
public Form getForm() {
if (form == null) {
// write pre-init user code here
form = new Form("form", new Item[] getChoiceGroup()});
form.addCommand(getBackCommand());
form.addCommand(getOkCommand());
form.addCommand(getExitCommand());
form.setCommandListener(this);
// write post-init user code here
}
return form;
}
public ChoiceGroup getChoiceGroup() {
if (choiceGroup == null) {
// write pre-init user code here
choiceGroup = new ChoiceGroup("Choices", Choice.EXCLUSIVE);
choiceGroup.append("Time Table", null);
choiceGroup.append("Exam Schedule", null);
choiceGroup.append("Marks", null);
choiceGroup.setSelectedFlags(new boolean[]{false, false, false});
// write post-init user code here
}
return choiceGroup;
}
public void commandAction(Command command, Displayable displayable) {
// write pre-action user code here
if (displayable == form) {
if (command == backCommand) {
// write pre-action user code here
// write post-action user code here
} else if (command == exitCommand) {
// write pre-action user code here
exitMIDlet();
// write post-action user code here
} else if (command == okCommand) {
// write pre-action user code here
switchDisplayable(null, getForm1());
// write post-action user code here
}
} else if (displayable == form1) {
if (command == backCommand1) {
// write pre-action user code here
// write post-action user code here
} else if (command == exitCommand1) {
// write pre-action user code here
exitMIDlet();
// write post-action user code here
}
}
// write post-action user code here
}
public Form getForm1() {
if (form1 == null) {
// write pre-init user code here
form1 = new Form("form1", new Item[]{getTableItem()});
form1.addCommand(getBackCommand1());
form1.addCommand(getExitCommand1());
form1.setCommandListener(this);
// write post-init user code here
}
return form1;
}
public TableItem getTableItem() {
if (tableItem == null) {
// write pre-init user code here
tableItem = new TableItem(getDisplay(), "tableItem");
// write post-init user code here
}
return tableItem;
}
public Command getBackCommand() {
if (backCommand == null) {
// write pre-init user code here
backCommand = new Command("Back", Command.BACK, 0);
// write post-init user code here
}
return backCommand;
}
public Command getOkCommand() {
if (okCommand == null) {
// write pre-init user code here
okCommand = new Command("Ok", Command.OK, 0);
// write post-init user code here
}
return okCommand;
}
public Command getExitCommand() {
if (exitCommand == null) {
// write pre-init user code here
exitCommand = new Command("Exit", Command.EXIT, 0);
// write post-init user code here
}
return exitCommand;
}
public Command getBackCommand1() {
if (backCommand1 == null) {
// write pre-init user code here
backCommand1 = new Command("Back", Command.BACK, 0);
// write post-init user code here
}
return backCommand1;
}
public Command getExitCommand1() {
if (exitCommand1 == null) {
// write pre-init user code here
exitCommand1 = new Command("Exit", Command.EXIT, 0);
// write post-init user code here
}
return exitCommand1;
}
public SimpleTableModel getSimpleTableModel() {
if (simpleTableModel == null) {
// write pre-init user code here
simpleTableModel = new SimpleTableModel(null, null);
// write post-init user code here
}
return simpleTableModel;
}
public Display getDisplay() {
return Display.getDisplay(this);
}
public void exitMIDlet() {
switchDisplayable(null, null);
destroyApp(true);
notifyDestroyed();
}
public void startApp() {
if (midletPaused) {
resumeMIDlet();
} else {
initialize();
startMIDlet();
}
midletPaused = false;
}
public void pauseApp() {
midletPaused = true;
}
public void destroyApp(boolean unconditional) {
}
}