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
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