LWUIT：需要帮助 `Back` 命令无法正常工作
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【中文标题】LWUIT：需要帮助 `Back` 命令无法正常工作【英文标题】：LWUIT: Need help `Back` command is not working properly 【发布时间】：2011-12-13 08:03:53 【问题描述】：我们使用表单显示 SPLASH 屏幕，然后是 MENU 表单，其中包含许多按钮，例如关于我们、登录、反馈等。
现在我转到包含menu 和back 命令的LOGIN 表单。我的问题是当back 以这种形式单击命令时，它会转到SPLASH 屏幕。
预期的行为是LOGIN 表单中的后退命令必须返回到MENU 表单而不是SPLASH 表单。
如何做到这一点？
Splash.java
public class Splash extends MIDlet implements ActionListener
Image img_Splash;
Form frm_Main;
String str_URL;
int Width, Height;
Label lbl_Splash;
Command cmd_Cancel;
public void startApp()
Display.init(this);
frm_Main = new Form();
try
//Resources theme = Resources.open("/44444.res");
img_Splash = Image.createImage("/res/splash.png");
Resources theme = Resources.open("/666666.res");
UIManager.getInstance().setThemeProps(
theme.getTheme(theme.getThemeResourceNames()[0]));
catch (IOException io)
io.printStackTrace();
Dialog.show("Theme Exception", io.getMessage(), "Ok", null);
lbl_Splash = new Label(img_Splash);
lbl_Splash.getStyle().setBgColor(16777215);
frm_Main.addComponent(lbl_Splash);
frm_Main.setScrollable(true);
cmd_Cancel = new Command("Cancel");
frm_Main.addCommand(cmd_Cancel);
frm_Main.addCommandListener(this);
frm_Main.show();
// th
Thread splashThread = new Thread()
public void run()
try
sleep(5000);
catch (InterruptedException ex)
ex.printStackTrace();
finally
MainMenu mainmenu = new MainMenu(frm_Main);
mainmenu.show();
;
splashThread.start();
public void pauseApp()
public void destroyApp(boolean unconditional)
//notifyDestroyed();
public void actionPerformed(ActionEvent ae)
Command con = ae.getCommand();
String str_CmdName = con.getCommandName();
if (str_CmdName.equals("Cancel"))
notifyDestroyed();
Mainmenu.java
class MainMenu extends Form implements ActionListener
Form frm_Main;
//MainMidlet main;
public Button btn_main_Login, btn_main_NewUser, btn_main_Help;
public Label lbl_main_Login, lbl_main_NewUser, lbl_main_Help;
public Image img_main_Login, img_main_NewUser, img_main_Help;
public Command cmd_Exit, cmd_Select;
public MainMenu(Form form)
this.frm_Main = form;
try
img_main_Login = Image.createImage("/res/btn_main_login.png");
img_main_NewUser = Image.createImage("/res/btn_main_newuser.png");
img_main_Help = Image.createImage("/res/btn_main_help.png");
catch (IOException io)
io.printStackTrace();
//Dialog.show("Image not Found!", io.getMessage(), "Ok", null);
System.out.println("Image not found" + io.getMessage());
//--------- Whole form define as BorderLayout with three Container.
BorderLayout bor_MainMenuLayout = new BorderLayout();
setLayout(bor_MainMenuLayout);
setScrollable(false);
//----------- Define Container for Header On North
Container con_Header = new Container();
lbl_Header = new Label(img_Header);
con_Header.addComponent(lbl_Header);
//----------- Define Container as GridLayout and place
//----------- on BorderLayout Center position
//--------- Define Container(CENTER) for search details
//--------- with BoxLayout
BoxLayout bx_CenterLayout = new BoxLayout(BoxLayout.Y_AXIS);
Container con_Center = new Container(bx_CenterLayout);
con_Center.setScrollableY(true);
con_Center.getStyle().setPadding(0, 10, 3, 3);
//--------- FlowLayout for Header Details
FlowLayout flw_MenuHdr = new FlowLayout();
Container con_HdrDetails = new Container(flw_MenuHdr);
lbl_MenuHdr = new Label("Menu");
lbl_MenuHdr.getStyle().setBgTransparency(0);
lbl_MenuHdr.getStyle().setPadding(0, 5, 10, 0);
con_HdrDetails.addComponent(lbl_MenuHdr);
con_Center.addComponent(con_HdrDetails);
//---------- GridLayout define 1 rows and 3 coloumn
//---------- First row
GridLayout grd_Row1Layout = new GridLayout(1, 3);
Container con_Row1Layout = new Container(grd_Row1Layout);
btn_main_Login = new Button(img_main_Login);
btn_main_Help = new Button(img_main_Help;
btn_main_NewUser = new Button(img_main_NewUser);
con_Row1Layout.addComponent(btn_main_Login);
con_Row1Layout.addComponent(btn_main_Help);
con_Row1Layout.addComponent(btn_main_NewUser);
con_Center.addComponent(con_Row1Layout);
//----------- Add Command on softkey
cmd_Exit = new Command("Exit");
cmd_Select = new Command("Select");
addCommand(cmd_Select);
addCommand(cmd_Exit);
addCommandListener(this);
addComponent(BorderLayout.NORTH, con_Header);
addComponent(BorderLayout.CENTER, con_Center);
//this.getStyle().setBgColor(12105912);
frm_Main.getStyle().setBgColor(12105912);
public void actionPerformed(ActionEvent ae)
Command cmd = ae.getCommand();
String str_CmdName = cmd.getCommandName();
//----------- When Click on Exit Button
if (str_CmdName.equals("Exit"))
//System.exit(0);
//frm_Main.notifyAll();
//----------- When Click on Select Button
if (str_CmdName.equals("Select"))
//----------- When Click on Login
if (btn_main_Login.hasFocus())
String str_MemberId = GlobalClass.getInstance().getMemberId();
if (!(str_MemberId == "" || str_MemberId == null))
SearchDiamond searchdiamond = new SearchDiamond(frm_Main);
searchdiamond.setTransitionInAnimator(
Transition3D.createRotation(800, true));
searchdiamond.show();
else
Login login = new Login(frm_Main);
login.setTransitionInAnimator(
Transition3D.createRotation(800, true));
login.show();
//----------- When Click on New User
if (btn_main_NewUser.hasFocus())
//Dialog.show("New User", "NewUser", "Ok", null);
NewUser newuser = new NewUser(frm_Main);
//newuser.setTransitionInAnimator(
CommonTransitions.createFade(1500));
newuser.setTransitionInAnimator(
Transition3D.createRotation(800, true));
newuser.show();
//----------- When Click on Help
if (btn_main_Help.hasFocus())
Help help = new Help(frm_Main);
help.setTransitionInAnimator(
Transition3D.createRotation(800, true));
help.show();
//----------- When Click on Exit
if (btn_main_Exit.hasFocus())
System.exit(0);
Login.java
class Login extends Form implements ActionListener
Form frm_Main;
Label lbl_Header, lbl_Footer, lbl_SepLine, lbl_HdrAlreadyMember, lbl_UserID, lbl_PWD,
lbl_Blank2, lbl_Blank3, lbl_HdrNewMember, lbl_Info;
TextField txtf_UserID, txtf_PWD;
Button btn_Login;
Command cmd_Back, cmd_AboutUs, cmd_Privacy;
public Login(Form form)
this.frm_Main = form;
//--------- Whole form define as BorderLayout with three Container.
BorderLayout bor_LoginLayout = new BorderLayout();
setLayout(bor_LoginLayout);
setScrollable(false);
//--------- Define Container(NORTH) for Header.
Container con_Header = new Container();
lbl_Header = new Label();
con_Header.addComponent(lbl_Header);
//--------- Define Container(CENTER) for search details
//--------- with BoxLayout
BoxLayout bx_CenterLayout = new BoxLayout(BoxLayout.Y_AXIS);
Container con_Center = new Container(bx_CenterLayout);
con_Center.setScrollableY(true);
con_Center.getStyle().setMargin(5, 5, 0, 0);
//--------- FlowLayout for Header Details
FlowLayout flw_HdrLayout = new FlowLayout();
Container con_HdrDetails = new Container(flw_HdrLayout);
lbl_HdrAlreadyMember = new Label("Already a Member?");
lbl_HdrAlreadyMember.setAlignment(Component.LEFT);
con_HdrDetails.addComponent(lbl_HdrAlreadyMember);
con_Center.addComponent(con_HdrDetails);
//--------- BoxLayout for Login details
BoxLayout bx_Login1Layout = new BoxLayout(BoxLayout.Y_AXIS);
Container con_Login1Details = new Container(bx_Login1Layout);
con_Login1Details.setScrollableY(true);
lbl_UserID = new Label("User Name:");
txtf_UserID = new TextField("");
txtf_UserID.setFocusable(true);
txtf_UserID.setFocus(true);
txtf_UserID.setConstraint(TextField.ANY);
txtf_UserID.setInputMode("abc");
lbl_PWD = new Label("Password:");
txtf_PWD = new TextField("");
txtf_PWD.setConstraint(TextField.PASSWORD);
con_Login1Details.addComponent(lbl_UserID);
con_Login1Details.addComponent(txtf_UserID);
con_Login1Details.addComponent(lbl_PWD);
con_Login1Details.addComponent(txtf_PWD);
//--------- BoxLayout for Login Button
FlowLayout flw_LoginBtnLayout = new FlowLayout(CENTER);
Container con_LoginBtnDetails = new Container(
flw_LoginBtnLayout);
con_LoginBtnDetails.setScrollableY(true);
btn_Login = new Button("Login");
btn_Login.setPreferredSize(new Dimension(80, 25));
btn_Login.setAlignment(Component.CENTER);
con_LoginBtnDetails.addComponent(btn_Login);
con_Login1Details.addComponent(con_LoginBtnDetails);
con_Center.addComponent(con_Login1Details);
//--------- BoxLayout for other Login details
BoxLayout bx_Login2Layout = new BoxLayout(BoxLayout.Y_AXIS);
Container con_Login2Details = new Container(bx_Login2Layout);
con_Login2Details.setScrollableY(true);
con_Login2Details.getStyle().setMargin(5, 5, 10, 10);
//--------- Login type 3 New Remember Me
chk_RememberMe = new CheckBox("Remember Me");
chk_RememberMe.setTickerEnabled(false);
con_Login2Details.addComponent(chk_RememberMe);
//--------- Login type 3 New Forgot Password
btn_ForgotPWD = new Button("Forgot Password?");
btn_ForgotPWD.setTickerEnabled(false);
btn_ForgotPWD.setAlignment(Component.LEFT);
btn_ForgotPWD.setTextPosition(Component.RIGHT);
con_Login2Details.addComponent(btn_ForgotPWD);
con_Center.addComponent(con_Login2Details);
con_Center.getStyle().setPadding(0, 0, 10, 10);
addComponent(BorderLayout.NORTH, con_Header);
addComponent(BorderLayout.CENTER, con_Center);
cmd_Back = new Command("Back");
this.setBackCommand(cmd_Back);
addCommand(cmd_Back);
addCommandListener(this);
//---------- Add More Command for Menu item
cmd_AboutUs = new Command("About Us");
cmd_Privacy = new Command("Privacy");
addCommand(cmd_AboutUs);
addCommand(cmd_Privacy);
//------- When Login Button is Clicked
btn_Login.addActionListener(new ActionListener()
public void actionPerformed(ActionEvent evt)
....
);
public void actionPerformed(ActionEvent ae)
Command con = ae.getCommand();
String str_CmdName = con.getCommandName();
if (str_CmdName.equals("Back"))
// here back code
frm_Main.setTransitionInAnimator(
Transition3D.createRotation(800, true));
frm_Main.showBack();
....
if (str_CmdName.equals("About Us"))
AboutUs aboutus = new AboutUs(frm_Main);
aboutus.show();
if (str_CmdName.equals("Privacy"))
Privacy privacy = new Privacy(frm_Main);
privacy.show();
编辑：添加了表单的源代码
【问题讨论】：
有很多未知的和场景会导致这个问题？请提供您的代码 sn-p 以获得更多帮助？ 感谢重播，我在这里添加了一些代码！请帮助我 我编辑了my answer。那里的问题解决说明。 非常欢迎，如果你能解决你的问题，请标记答案和accept it，以帮助这篇文章的未来读者。 【参考方案1】：知道了！
在MainMenu(...) 构造函数中，您将SPLASH 屏幕的引用存储在类变量frm_Main 中，您将这个类变量传递给MainMenu.actionPerformed(...) 中的Login(...) 构造函数，因此您正在有效地传递引用Splash 表单对象。您需要将当前类 MainMenu's 引用传递给 Login(...) 构造函数，而不是 MainMenu.frm_Main。
如果您不希望从MainMenu 屏幕返回Splash 屏幕，请执行此操作：
public MainMenu(Form form)
this.frm_Main = this; //by referring to `MainMenu.this` and not input
//parameter `form` which is referring to Splash
//object
...
如果您想维护 MainMenu 屏幕的后向引用，请在 MainMenu.actionPerformed(...) 中执行此操作
Login login = new Login(/*global variable for `MainMenu.this`*/);
【讨论】：
@HarshadaDhamapurkar 如果您认为它有助于解决您的问题，请标记并接受此答案。以上是关于LWUIT：需要帮助 `Back` 命令无法正常工作的主要内容，如果未能解决你的问题，请参考以下文章