java - J2MEボタンコマンドが機能しない

Question

私は現在j2meアプリケーションに取り組んでおり、コマンドボタンを処理するのに苦労しています。誰か助けてくれませんか。ボタンは2番目のフォームに表示されるはずでしたが、クリックしても機能しません。これが私のコードです：

        import javax.microedition.midlet .*; 
        import javax.microedition.lcdui .*; 
        import javax.microedition.lcdui.StringItem;
        import javax.microedition.lcdui.TextField;
        import javax.microedition.lcdui.DateField;
        import javax.microedition.lcdui.Command;
        import javax.microedition.lcdui.Alert;
        import javax.microedition.pim.PIM;
        import javax.microedition.pim.PIMItem;
        import javax.microedition.pim.PIMException;
        import java.util.Date;
        import java.util.Enumeration;
        import javax.microedition.lcdui.Choice;
        import javax.microedition.lcdui.List;
        import javax.microedition.pim.ToDo;
        import javax.microedition.pim.ToDoList;
        import javax.microedition.lcdui.Displayable;
        import javax.microedition.lcdui.Display;
        import javax.microedition.lcdui.Form;
        import javax.microedition.lcdui.CommandListener;

        public class MainMidlet extends MIDlet implements CommandListener, 
        ItemCommandListener { 

        private Form aform, bform, addToDoForm; 
        private Command okCommand; 
        private Command exitCommand;
        private Command cmdAddTodo;
        private Command cmdretrieveTodo;
        private Command cmdExit;
        private Command backCommand;
        private Command hllinkCommand; 
        private Command b1Command, b2Command; 
        private Display aDisplay; 
        private StringItem hlstringItem,hlstringItem2; 
        private StringItem b1stringItem, b2stringItem, b1stringItem2, b2stringItem2;   
        private Alert hlAlert; 
        private Alert b1Alert, b2Alert;
        private TextField summaryField;
        // Date field for Due data of ToDo.
        private DateField dueDateField;
        // Date field for end data of ToDo.
        private TextField noteField;
        // Text field to set priority of ToDo.
        private TextField priorityField;
        private List listTodos;
        private ToDoList todoList;
        private ToDo todo;

        public MainMidlet () { 
        okCommand = new Command ( "OK", Command.OK, 1); 
        exitCommand = new Command ( "EXIT", Command.EXIT, 1);
        backCommand = new Command ( "BACK", Command.BACK, 1);
        hllinkCommand = new Command ( "LINK", Command.ITEM, 2); 
        b1Command = new Command ( "BUTTON", Command.ITEM, 2);
        b2Command = new Command ( "BUTTON", Command.ITEM, 2);

        aform = new Form ( "CyberMe");

        // if click hyperlink "here", display anAlert 
        hlstringItem = new StringItem (null, "here", Item.HYPERLINK); 
        hlstringItem.setItemCommandListener (this); 
        hlstringItem.setDefaultCommand (hllinkCommand); 

        b1stringItem = new StringItem (null, "Make ToDo", Item.BUTTON); 
        b1stringItem.setItemCommandListener (this); 
        b1stringItem.setDefaultCommand (b1Command);

        b2stringItem = new StringItem (null, "Set Alarm", Item.BUTTON); 
        b2stringItem.setItemCommandListener (this); 
        b2stringItem.setDefaultCommand (b2Command);

        /*hlstringItem2 = new StringItem (null, "here", Item.HYPERLINK); 
        hlstringItem2.setItemCommandListener (this); 
        hlstringItem2.setDefaultCommand (hllinkCommand); 

        b1stringItem2 = new StringItem (null, "Make ToDo", Item.BUTTON); 
        b1stringItem2.setItemCommandListener (this); 
        b1stringItem2.setDefaultCommand (b1Command);

        b2stringItem2 = new StringItem (null, "Set Alarm", Item.BUTTON); 
        b2stringItem2.setItemCommandListener (this); 
        b2stringItem2.setDefaultCommand (b2Command);*/


        hlAlert = new Alert ( "Item.HYPERLINK", "You Can Call Me 800-8101234" 
        , null, AlertType.INFO); 
        b1Alert = new Alert ( "Item.Button", "You click ToDo!" 
        , null, AlertType.INFO);
        //b2Alert = new Alert ( "Item.Button", "You click Alarm!" 
        //, null, AlertType.INFO);


        aform.append ( "What do you want to do?"); 
        aform.append (hlstringItem); 
        aform.append (b1stringItem);
        aform.append (b2stringItem);

        aform.addCommand (okCommand); 
        aform.addCommand (exitCommand); 
        aform.setCommandListener (this); 

        /*bform.append ( "What do you want to do?"); 
        bform.append (hlstringItem2); 
        bform.append (b1stringItem2);
        bform.append (b2stringItem2);

        bform.addCommand (okCommand); 
        bform.addCommand (backCommand); 
        bform.setCommandListener (this); */

        }

        /*public void SecondPage(){
        if(checkPIMSupport() == false) {
        exitMIDlet();
        }

        setComponents();
        }

        /**
        * Initializes components of MIDlet.
        */
        public void setComponents() {

        aDisplay = Display.getDisplay(this);

        // Create form for adding ToDo.
        addToDoForm = new Form("ToDo");

        // Add commands to form and set listener for it.
        cmdAddTodo = new Command("Add Todo", Command.SCREEN, 0);
        cmdretrieveTodo = new Command("Retrieve All Todos", Command.SCREEN, 0);
        addToDoForm.addCommand(cmdAddTodo);
        addToDoForm.addCommand(cmdretrieveTodo);

        cmdExit = new Command("Exit", Command.EXIT, 0);
        addToDoForm.addCommand(cmdExit);

        addToDoForm.setCommandListener(this);
        listTodos = new List("ToDo list", Choice.IMPLICIT);
        backCommand =new Command("Back", Command.BACK, 0);
        listTodos.addCommand(backCommand);
        listTodos.setCommandListener(this);

        try {

        StringBuffer supported = new StringBuffer();

        // Get list of ToDos.
        todoList = (ToDoList)PIM.getInstance().openPIMList(
        PIM.TODO_LIST, PIM.READ_WRITE);

        // Create controls based on supported fields for ToDo.
        if(todoList.isSupportedField(ToDo.SUMMARY) == true) {
        summaryField = new TextField("Summary", null, 20,
                                TextField.ANY);
        addToDoForm.append(summaryField);
        } 

        else {

        supported.append("Summary field\n");
        removeCommand();

        }

        if(todoList.isSupportedField(ToDo.DUE) == true) {
        dueDateField = new DateField("Date",
                                DateField.DATE_TIME);
        dueDateField.setDate(new Date());
        addToDoForm.append(dueDateField);

        }

        else {

        supported.append("Due date field\n");
        removeCommand();

        }


        if(todoList.isSupportedField(ToDo.NOTE) == true) {
        noteField = new TextField("Information", null, 20, TextField.ANY);
        addToDoForm.append(noteField);
        }

        else {

        supported.append("Note field\n");
        }

        if(todoList.isSupportedField(ToDo.PRIORITY) == true) {
        priorityField = new TextField("Priority", null, 20,
                                TextField.NUMERIC);

        addToDoForm.append(priorityField);
        }
        else {

        supported.append("Priority field\n");
        removeCommand();
        }

        if(supported.length()!=0){

            StringItem si = new StringItem("ToDo field not supported", "");     
            si.setText(supported.toString());
            addToDoForm.append(si);
        }


        } catch(PIMException pimExc) {
        // TODO: Handle error on working with PIM.
        }
        catch(SecurityException secExc) {
        // TODO: Handle error on access to PIM.
        }
        catch(Exception exc) {
        // If unknown error was caught, show it to the end user.
        showAlert("Info", exc.toString());  
        }

        }

        // Remove the command for adding ToDos
        public void removeCommand(){
        addToDoForm.removeCommand(cmdAddTodo);
        }

        public void listToDos() {

        Enumeration todos = null;

        try {
        todoList = (ToDoList) PIM.getInstance().openPIMList(PIM.TODO_LIST, PIM.READ_WRITE);

        } catch (PIMException e) {
        // Cannot open ToDo list
        showAlert("Info", "Failed to open a ToDo list: "+e.toString());  
        return;
        } catch (SecurityException e) {
        // User rejects application's request for reading ToDo list
        showAlert("Info", "Reading ToDo List rejected: "+e.toString());  
        return;
        }

        try {
        // Get the enumeration of all ToDo elements
        todos = todoList.items();

        } catch (PIMException e) {
        // Failed to retrieve elements
        showAlert("Info", "This application cannot retrieve ToDos: "+e.toString());  
        }

        if (listTodos.size() > 0) {
        listTodos.deleteAll();
        }

        while (todos.hasMoreElements()) {
        todo =  (ToDo) todos.nextElement();
        String todoInfo = null;
        try {
        todoInfo = todo.getString(ToDo.SUMMARY, PIMItem.ATTR_NONE);

        } catch (Exception ex) {
        showAlert("Info",ex.getMessage());
        continue;
        }
        if (todoInfo != null) {
        listTodos.append(todoInfo, null);
        }          
        }
        }

        /**
        * Checks PIM support.
        * @return - true if PIM is supported, false otherwise.
        */

        private boolean checkPIMSupport() {
        String propValue = System.getProperty("microedition.pim.version");
        if(propValue != null) {
        return true;
        } else {
        return false;
        }
        }



        private void getToDoList() {
        listToDos();
        aDisplay.setCurrent(listTodos);
        }

        /**
        * Adds ToDo to list of ToDos.
        * Gets data for ToDo from addToDoForm controls.
        */
        private void addToDo() {

        try {

        // Get list of ToDos.
        todoList = (ToDoList)PIM.getInstance().openPIMList(
        PIM.TODO_LIST, PIM.READ_WRITE);

        // Create new ToDo.
        todo = todoList.createToDo();

        // Get data from controls
        if(todoList.isSupportedField(ToDo.SUMMARY) == true) {

        if(summaryField.size()==0){

        showAlert("Info", "Summary missing, please enter a summary");
        return;
        }
        String summary =summaryField.getString();
        todo.addString(ToDo.SUMMARY, PIMItem.ATTR_NONE, summary);
        } else {
        // At least summary must be supported.
        closeToDoList();
        showAlert("Info", "Summary field for ToDo is not supported");
        }

        if(todoList.isSupportedField(ToDo.DUE) == true) {
        long startDate = dueDateField.getDate().getTime();
        todo.addDate(ToDo.DUE, PIMItem.ATTR_NONE, startDate);
        }   

        if(todoList.isSupportedField(ToDo.NOTE) == true) {
        String note = noteField.getString();
        todo.addString(ToDo.NOTE, PIMItem.ATTR_NONE, note);
        }

        if(todoList.isSupportedField(ToDo.PRIORITY) == true) {

        if(priorityField.size()==0){

        showAlert("Info", "Priority is missing, please enter a priority");
        return;
        }

        else {

            String  location = priorityField.getString();
            int i=Integer.parseInt(location);              

            if(i > 9){

            showAlert("Info","Priority exceeded, please enter a priority between 0-9");
                    return;
            }                

            todo.addInt(ToDo.PRIORITY, PIMItem.ATTR_NONE, i);           
        }
        }

        // Commit ToDo.
        todo.commit();

        // Notify user that ToDo was added
        showAlert("Info", "ToDo was successfully added");  

        } catch(PIMException pimExc) {
        // TODO: Handle error on working with PIM.
        showAlert("Info", pimExc.getMessage());
        }
        catch(SecurityException secExc) {
        // TODO: Handle error on access to PIM.
        showAlert("Info", secExc.getMessage());
        }

        catch(Exception exc) {

        // TODO: Handle all other errors.
        showAlert("Info", exc.toString());

        }

        }

        /**
        * Shows alert with specified title and text.
        * @param title - Title of alert.
        * @param message - text of alert.
        */
        private void showAlert(String title, String message) {
        Alert alert = new Alert(title);
        alert.setString(message);
        alert.setTimeout(2000);
        aDisplay.setCurrent(alert);
        }

        /**
        * From MIDlet.
        * Signals the MIDlet that it has entered the Active state.
        */


        public void startApp () { 
        aDisplay = Display.getDisplay (this); 
        aDisplay.setCurrent (aform); 


        } 

        public void pauseApp () { 
        } 

        public void destroyApp (boolean unconditional) {

        } 
        private void exitMIDlet() {
        notifyDestroyed();
        }

        private void closeToDoList() {
        if (todoList != null) {
        try {

        todoList.close();
        } catch (PIMException ex) {
        showAlert("Info","Error in closing ToDo list: "+ex.toString());
        }
        }
        todoList = null;
        }
        public void commandAction (Command c, Displayable d) { 

        if (c == exitCommand) { 
        destroyApp (false); 
        notifyDestroyed (); 
        } 
        if(c == backCommand){ 
        aDisplay.setCurrent(aform);
        } 
        }

        public void commandAction (Command c, Item i) { 

        if (c == hllinkCommand) { 
        aDisplay.setCurrent (hlAlert, aform); 
        } 
        if (c == b1Command) { 
        aDisplay.setCurrent (b1Alert, aform); 
        }
        if (c == b2Command){
        aDisplay.setCurrent (addToDoForm);
        }

        } 
        }

Answer 1

あなたの当面の間違い-そしてそれはあなたのすべての問題の中で最もマイナーなokCommandものです-あなたがで処理するのを忘れたということですcommandAction(Command, Displayable)。

その結果、ユーザーが[OK]をクリックしても、何も起こりません。これを処理するコードがないからです。

この間違いは簡単に修正できます-commandActionに-ItemではなくDisplayableを処理するコードに追加するだけです-以下のようなコードで完了です：

        if(c == okCommand){ 
            // show whatever screen you need
            aDisplay.setCurrent(new Form("whatever"));
        } 

しかし、これで問題が解決するわけではありません。このようなコードを使用すると、微妙な間違いを犯して頭を壊して修正する運命にあるからです。

ささいなことを終えたので、最初の悪い間違いは、ユーザーアクションのポイントとブロック内でのロギングの欠如ですcatch（catchブロックについて言及する理由については、WebでJava飲み込み例外のようなものを検索してください）。

これにより、デバッグ時にそこで何が起こっているのかを理解することが不必要に困難になります。上記の処理が欠落しているなどのバグは、okCommandMIDletを実行し、そこにログが記録されている場合はエミュレータコンソールを調べるだけで簡単に見つけることができます。

ロギングを推奨するユーザーアクションのポイントはcommandAction、を呼び出すときsetCurrentです。開発するときは、必要に応じて自由に追加してください（Canvasを使用している場合はkeyPressed、その候補としても適しています）。

public class Log {
    // utility class to keep logging code in one place
    public static void log (String message) {
        System.out.println(message);
        // when debugging at real device, S.o.p above can be refactored
        //  - based on ideas like one used here (with Form.append):
        //    http://stackoverflow.com/questions/10649974
        //  - Another option would be to write log to RMS
        //    and use dedicated MIDlet to read it from there
        //  - If MIDlet has network connection, an option is
        //    to pass log messages over the network. Etc etc...
    }
}


// ... other classes...
    // ...
    catch (Exception e) {
        Log.log("unexpected exception: [" + e + "]");
    }

    // ...
    public void commandAction(Command c, Displayable s) {
        Log.log("command: [" + c.getCommandLabel()
                + "] at screen: [" + d.getTitle() + "]");
        // ...
    }

    // ...
    public void commandAction(Command c, Item i) {
        Log.log("command: [" + c.getCommandLabel()
                + "] at item: [" + i.getLabel() + "]");
        // ...
    }

    // ...
    Log.log("set current: [" + someDisplayable.getTitle() + "]");
    display.setCurrent(someDisplayable);
    // ...

    protected void keyPressed(int key) { // in Canvas
        Log.log("key pressed: [" + getKeyName(key) + "]");
        // ...
    }

コードのもう1つの本当に悪い間違いは、それが神オブジェクトであるということです。これにより、変更とデバッグが不必要に困難になります。アプリケーションをより小さなクラスに分割します。すべてを1か所にまとめる必要はありません。

まず、MainMidletにこれらを実装させるのではなく、CommandListenerとItemCommandListenerを別々のクラスに移動することを検討してください。画面ごとに1つなど、複数のItem/CommandListenerが存在する可能性があることに注意してください。

のコンテンツに関連するコードをaform別のクラスに分割します。bform、addToDoForm、listTodosと同じです。等