问题描述
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我已经学习J2ME已有几天了。但是我有一个大问题；我的移动应用程序大约有5页：第一页扩展了MIDlet，其他页面扩展了表单。加载第一页后，我使用命令切换到其他页面，但是当我进入新页面（扩展形式）时，我附加的所有命令都没有响应。我需要洞察力来解决这个问题。我的代码如下；
初始页；
/*
* To change this template,choose Tools | Templates
* and open the template in the editor.
*/
package report;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import org.netbeans.microedition.lcdui.SimpleTableModel;
import org.netbeans.microedition.lcdui.TableItem;
/**
* @author Possicon
*/
public class Reports extends MIDlet implements CommandListener {
private boolean midletPaused = false;
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Fields \">
private Form form;
private Command SendReport;
private Command SendPictureReport;
private Command exitCommand;
private Command viewReport;
private Command subscribe;
private Command spotted;
private Command sortBy;
private SimpleTableModel tableModel1;
//</editor-fold>
/**
* The Reports constructor.
*/
public Reports() {
//startMIDlet();
}
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Methods \">
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Method: initialize \">
/**
* Initializes the application.
* It is called only once when the MIDlet is started. The method is called before the <code>startMIDlet</code> method.
*/
private void initialize() {
// write pre-initialize user code here
// write post-initialize user code here
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Method: startMIDlet \">
/**
* Performs an action assigned to the Mobile Device - MIDlet Started point.
*/
public void startMIDlet() {
// write pre-action user code here
getdisplay().setCurrent(getForm());
// write post-action user code here
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Method: resumeMIDlet \">
/**
* Performs an action assigned to the Mobile Device - MIDlet Resumed point.
*/
public void resumeMIDlet() {
// write pre-action user code here
// write post-action user code here
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Method: switchdisplayable \">
/**
* Switches a current displayable in a display. The <code>display</code> instance is taken from <code>getdisplay</code> method. This method is used by all actions in the design for switching displayable.
* @param alert the Alert which is temporarily set to the display; if <code>null</code>,then <code>nextdisplayable</code> is set immediately
* @param nextdisplayable the displayable to be set
*/
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
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Method: commandAction for displayables \">
/**
* Called by a system to indicated that a command has been invoked on a particular displayable.
* @param command the Command that was invoked
* @param displayable the displayable where the command was invoked
*/
public void commandAction(Command command,displayable displayable) {
// write pre-action user code here
if (displayable == form) {
if (command == SendReport) {
// write pre-action user code here
getdisplay().setCurrent(new SendReport());
// 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 == sortBy) {
// write pre-action user code here
// write post-action user code here
} else if (command == spotted) {
// write pre-action user code here
getdisplay().setCurrent(new Spotted());
// write post-action user code here
} else if (command == subscribe) {
// write pre-action user code here
//getdisplay().setCurrent(new Subscribe());
new Subscribe().getMydisplay(getdisplay());
// write post-action user code here
}
}
// write post-action user code here
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Getter: form \">
/**
* Returns an initiliazed instance of form component.
* @return the initialized component instance
*/
public Form getForm() {
if (form == null) {
// write pre-init user code here
form = new Form(\"Traffic Reports\",new Item[] { });
form.addCommand(getSortBy());
form.addCommand(getSendReport());
form.addCommand(getSubscribe());
form.addCommand(getExitCommand());
form.addCommand(getSpotted());
form.setCommandListener(this);
// write post-init user code here
loadReports(form);
//form.append(getTableModel1());
}
return form;
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Getter: SendReport \">
/**
* Returns an initiliazed instance of SendReport component.
* @return the initialized component instance
*/
public Command getSendReport() {
if (SendReport == null) {
// write pre-init user code here
SendReport = new Command(\"Send Report\",Command.SCREEN,0);
// write post-init user code here
}
return SendReport;
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Getter: SendPictureReport \">
/**
* Returns an initiliazed instance of SendPictureReport component.
* @return the initialized component instance
*/
public Command getSendPictureReport() {
if (SendPictureReport == null) {
// write pre-init user code here
SendPictureReport = new Command(\"Send Picture Report\",0);
// write post-init user code here
}
return SendPictureReport;
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Getter: tableModel1 \">
/**
* Returns an initiliazed instance of tableModel1 component.
* @return the initialized component instance
*/
public SimpleTableModel getTableModel1() {
if (tableModel1 == null) {
// write pre-init user code here
tableModel1 = new SimpleTableModel(new java.lang.String[][] {
new java.lang.String[] { \"Traffic on Ikorodu road,free\" },new java.lang.String[] { \"Adeola Odeku is free\" },new java.lang.String[] { \"Accident on Ahmadu Bellow\" }},null);
// write post-init user code here
}
return tableModel1;
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Getter: exitCommand \">
/**
* Returns an initiliazed instance of exitCommand component.
* @return the initialized component instance
*/
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;
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Getter: viewReport \">
/**
* Returns an initiliazed instance of viewReport component.
* @return the initialized component instance
*/
public Command getViewReport() {
if (viewReport == null) {
// write pre-init user code here
viewReport = new Command(\"View Reports\",0);
// write post-init user code here
}
return viewReport;
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Getter: subscribe \">
/**
* Returns an initiliazed instance of subscribe component.
* @return the initialized component instance
*/
public Command getSubscribe() {
if (subscribe == null) {
// write pre-init user code here
subscribe = new Command(\"Subscribe\",0);
// write post-init user code here
}
return subscribe;
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Getter: spotted \">
/**
* Returns an initiliazed instance of spotted component.
* @return the initialized component instance
*/
public Command getSpotted() {
if (spotted == null) {
// write pre-init user code here
spotted = new Command(\"Spotted\",0);
// write post-init user code here
}
return spotted;
}
//</editor-fold>
//<editor-fold defaultstate=\"collapsed\" desc=\" Generated Getter: sortBy \">
/**
* Returns an initiliazed instance of sortBy component.
* @return the initialized component instance
*/
public Command getSortBy() {
if (sortBy == null) {
// write pre-init user code here
sortBy = new Command(\"Sort By\",0);
// write post-init user code here
}
return sortBy;
}
//</editor-fold>
/**
* Returns a display instance.
* @return the display instance.
*/
public display getdisplay() {
return display.getdisplay(this);
}
/**
* Exits MIDlet.
*/
public void exitMIDlet() {
switchdisplayable(null,null);
destroyApp(true);
notifyDestroyed();
}
/**
* Called when MIDlet is started.
* Checks whether the MIDlet have been already started and initialize/starts or resumes the MIDlet.
*/
public void startApp() {
if (midletPaused) {
resumeMIDlet();
} else {
initialize();
//Login displayed = Login.displayed(1);
//getdisplay().setCurrent(new Login());
startMIDlet();
}
midletPaused = false;
}
/**
* Called when MIDlet is paused.
*/
public void pauseApp() {
midletPaused = true;
}
/**
* Called to signal the MIDlet to terminate.
* @param unconditional if true,then the MIDlet has to be unconditionally terminated and all resources has to be released.
*/
public void destroyApp(boolean unconditional) {
}
public void loadReports(Form form){
String string[] ={\"Traffic is here\",\"Traffic is bad here\",\"Accident Occured here\"};
StringItem st;
for(int i=0; i<string.length; i++){
st = new StringItem(\"\",string[i]);
form.append(st);
}
}
/*
public Array fetchReports(){
}
*
*/
}
/*
* To change this template,choose Tools | Templates
* and open the template in the editor.
*/
package report;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.DateField;
import javax.microedition.lcdui.display;
import javax.microedition.lcdui.displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.Item;
import javax.microedition.lcdui.ItemStateListener;
import javax.microedition.lcdui.StringItem;
import javax.microedition.lcdui.TextField;
/**
* @author Possicon
*/
public class Subscribe extends Form implements CommandListener,ItemStateListener {
private Form form;
private StringItem label;
private display display;
private Command save;
private Command subscribe;
private Command spotted;
private Command sendReport ;
private Command viewReport;
private Command exit;
private Command back ;
private TextField email,phone,route;
private DateField time,timet;
/*
public Subscribe(){
super(\"\");
}
*
*/
public Subscribe() {
//display = display.getdisplay(this);
//display = displ;
//form = new Form(\"Traffic Subscription\");
super(\"Traffic Subscription\");
label = new StringItem(\"Subscribe to recieve Traffic Alerts: \",\"\");
email = new TextField(\"Email: \",\"\",50,TextField.EMAILADDR);
phone = new TextField(\"Phone: \",11,TextField.ANY);
route = new TextField(\"Road: \",20,TextField.ANY);
//twitter = new TextField(\"Twitter: \",TextField.);
time = new DateField(\"Between: \",DateField.TIME);
timet = new DateField(\"To: \",DateField.TIME);
//DateFielddateField= new DateField(“Date:”,DateField.DATE);
java.util.Date date = new java.util.Date();
time.setDate(date);
append(label);
append(email);
append(phone);
append(route);
append(time);
append(timet);
save = new Command(\"Save\",1);
spotted = new Command(\"Spotted\",4);
sendReport = new Command(\"Send Report\",2);
viewReport = new Command(\"Reports\",3);
exit = new Command(\"Exit\",0);
//back = new Command(\"Back\",Command.BACK,0);
addCommand(exit);
addCommand(viewReport);
addCommand(sendReport);
addCommand(save);
addCommand(spotted);
//return form;
}
public void commandAction(Command command,displayable dsplbl) {
if (command == sendReport) {
// write pre-action user code here
new Reports().switchdisplayable(null,new SendReport());
//display.setCurrent(new SendReport());
// write post-action user code here
} else if (command == exit) {
// write pre-action user code here
//exitMIDlet();
// write post-action user code here
} else if (command == spotted) {
// write pre-action user code here
display.setCurrent(new Spotted());
// write post-action user code here
}
}
public void itemStateChanged(Item item) {
}
public void save(){
}
}
解决方法
在您的订阅表单中，没有将CommandListener附加到订阅表单。因此，在Form上添加命令后，像attach2一样附加CommandListener。
谢谢