Java访问类外的公共变量,SecurityException：MIDlet不是由createMIDlet构造的

我是java的新手,我有一个小问题.我想从另一个类访问一个类中的变量.我有三个类,我希望能够访问主类中的变量以使我能够读取数组.

我得到的错误是

    java.lang.SecurityException: MIDlet not constructed by createMIDlet

请参阅下面的示例.请记住,它们都在同一个包装中.

    package tungPackage;

    import com.sun.lwuit.*;
    import com.sun.lwuit.animations.CommonTransitions;
    import com.sun.lwuit.events.ActionEvent;
    import com.sun.lwuit.events.ActionListener;
    import javax.microedition.midlet.MIDlet;


    public class TungMidlet extends MIDlet implements ActionListener {
    private Command       back                = new Command("Back");
    private Command       ok                  = new Command("Ok");

    public ActionListener commandlistListener = new ActionListener() {
        public void actionPerformed(ActionEvent cmd) {

            // check which command cliked
            if (cmd.getCommand() == back) {

                // go back to previous form
                mainForm.show();
            } else if (cmd.getCommand() == ok) {

                // go forward
            }
        }
    };

    private List              list;
    private Form              mainForm;
    private Label             promptLabel;

    private housesClass houseClassObject = new housesClass();

    public int counter; //this is the variable I want to access in a class called calculate class object.

    private int sumAmmt;

    public TungMidlet tungMidletObject;
    public calculateClass calculateClassObject;



    public TungMidlet() {
        Display.init(this);
    }
    private ActionListener applistListener = new ActionListener() {
        public void actionPerformed(ActionEvent ae) {

            if(list.getSelectedIndex()==0){

                counter++;

                if (counter>5)
                {
                    //check sum price.
                    sumAmmt = calculateClassObject.calculateSum();
                    Dialog x = new Dialog("info");
                    Label label = new Label("Maximum reached.");
                    Label label2 = new Label("Sum ammt = "+sumAmmt);
                    x.addComponent(label);
                    x.addComponent(label2);
                    x.addCommand(ok);
                    x.show();
                }
                else

                {
                    //calculate the price
                    String info = houseClassObject.randomHouse();
                    Dialog x = new Dialog("info");
                    Label label = new Label(info);
                    x.addComponent(label);
                    x.addCommand(ok);
                    x.show();
                }

            }
        }
    };


    public void startApp() {
      //calculateClassObject = new calculateClass();

       //sumAmmt = calculateClassObject.calculate(sumAmmt);

        mainForm     = new Form("Investment Categories");
        promptLabel = new Label("choose category");

        list = new List();
        list.addItem("House");
        list.addItem("Cars");
        list.addItem("Schools");
        list.addItem("Schools");
        list.addItem("Supermarkets");
        list.addItem("Stocks");
        list.addItem("Land");

        list.addActionListener(applistListener);

        mainForm.addComponent(promptLabel);
        mainForm.addComponent(list);
        mainForm.addCommand(back);
        mainForm.addCommandListener(commandlistListener);
        mainForm.setTransitionInAnimator(CommonTransitions.createSlide(CommonTransitions.SLIDE_HORIZONTAL, true, 1000));
        mainForm.show();
    }

    public void pauseApp() {}

    public void destroyApp(boolean unconditional) {}


    public void actionPerformed(ActionEvent ae) {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    }

我想要使​​用“计数器”变量访问的类如下所示.

    package tungPackage;

     import java.util.Random;


     public class housesClass {
     public Random   generator  = new Random();
     public String[] houseArray = new String[5];
     public housesClass housesClassObject;

     public calculateClass calcobj;// = new calculateClass();

     public housesClass()
        {
        }

     public String randomHouse() {

       housesClassObject = new housesClass();

        houseArray[0] = "Bungalow - 20,000,000 Shillings";
        houseArray[1] = "Microhouse - 10,000,000 Shillings";
        houseArray[2] = "Flat - 200,000,000 shillings";
        houseArray[3] = "Garage apartment  - 7,000,000 shillings";
        houseArray[4] = "Studio apartment  - 13,000,000 shillings";

        int rnd = generator.nextInt(houseArray.length);

        housesClassObject.housePrices(rnd);///noma

        String house = houseArray[rnd];

        return house;
    }
     void housePrices(int houseNumber) {
     calcobj = new calculateClass();
     TungMidlet tungmidobj = new TungMidlet();
     int counter = tungmidobj.counter;
     int[] housePriceArray = new int[5];
     housePriceArray[0] = 20000000;
     housePriceArray[1] = 10000000;
     housePriceArray[2] = 200000000;
     housePriceArray[3] = 7000000;
     housePriceArray[4] = 13000000;

     int price = housePriceArray[houseNumber];

     calcobj.storePrice(counter,price);
    }
    }

另一个支持类如下所示.

     package tungPackage;

     public class calculateClass {
     int[] storeArray = new int[5];



     public calculateClass()
     { 
     }

     public void storePrice(int counter, int number2)
     {
     storeArray[counter] = number2;      
     }

    public int calculateSum()
    {
            int sum =0;

           for(int i=1; i<6; i++){
              sum= sum+storeArray[i];
         }
           return sum;
     }
    }

解决方法:

>删除TungMidlet构造函数.如果在那里有一些有用的东西,你也可以声明它受到保护 – 但是你的代码片段不是这种情况,见下文.
无论您何时尝试直接调用该构造函数,请删除执行此操作的代码并找到另一种方法来执行您所需的操作.如果需要,请研究LWUIT Tutorial – Introduction中提供的代码示例,了解LWUIT中的典型事项.
>在startApp方法的开头放置语句Display.init(),
就像在LWUIT Tutorial – Hello, LWUIT!示例代码中完成的那样

您获得SecurityException的原因是您直接调用TungMidlet构造函数.不要那样做.

> MIDP API documentation for MIDlet constructor州：

Throws:
SecurityException – unless the application management software is creating the MIDlet.

标签：java,java-me,lwuit,midp
来源： https://codeday.me/bug/20190613/1233717.html