我对Java很陌生,几天来我一直在努力解决一个可能非常简单的问题,但我真的无法解决。我有两个公共类,都是外部类的内部类。在第一个中,我得到了一些数据(来自眼动仪设备)。在第二个中,我想将它们绘制在图像上。我正确地获取数据并将它们存储在数组列表中,但是当我在第二个方法中使用它们时,我得到了一个空的数组列表。这里的代码:
import ...
public class TETSimple {
//static LoadImageApp image = new LoadImageApp();
public ArrayList x1;
public ArrayList y1;
public static void main(String[] args) {
final GazeManager gm = GazeManager.getInstance();
boolean success = gm.activate(ApiVersion.VERSION_1_0, ClientMode.PUSH);
final GazeListener gazeListener = new GazeListener();
gm.addGazeListener(gazeListener);
JFrame f = new JFrame("Immagine");
LoadImageApp a = new LoadImageApp();
f.add(a);
f.pack();
f.setVisible(true);
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
gm.removeGazeListener(gazeListener);
gm.deactivate();
}
});
}
public static class GazeListener
implements IGazeListener {
private ArrayList<Double> x1 = new ArrayList<Double>();
private ArrayList<Double> y1 = new ArrayList<Double>();
public ArrayList getX1() {
return this.x1;
}
public ArrayList getY1() {
return this.y1;
}
public void setX1(ArrayList l1) {
x1 = l1;
}
public void setY1(ArrayList l2) {
x1 = l2;
}
@Override
public void onGazeUpdate(GazeData gazeData) {
Double xcor = gazeData.smoothedCoordinates.x;
Double ycor = gazeData.smoothedCoordinates.y;
x1.add(new Double(xcor));
y1.add(new Double(ycor));
//System.out.println(x1.toString()); --> it works and returns all the values detected and added into the array
}
}
public static class LoadImageApp
extends Component {
BufferedImage img;
public Integer x;
public Integer y;
public void paint(Graphics g) {
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
Double screenW = screenSize.getWidth();
Double screenH = screenSize.getHeight() * 0.95;
int screenWidth = screenW.intValue();
int screenHeight = screenH.intValue();
// Dimensioni dell'immagine
if (img == null) {
return;
}
int imageWidth = img.getWidth(this);
int imageHeight = img.getHeight(this);
g.drawImage(img, 0, 0, screenWidth, screenHeight, 0, 0, imageWidth, imageHeight, null);
GazeListener a = new GazeListener();
System.out.println(a.getX1().toString()); //--> doesn't work, return an empty array
if (a.x1 != null && !a.x1.isEmpty() && a.y1 != null && !a.y1.isEmpty()) {
Double currentx = a.x1.get(a.x1.size() - 1);
Double currenty = a.y1.get(a.x1.size() - 1);
System.out.println(currentx);
} else {
System.out.println("empty array");
}
}
// costruttore della classe:
public LoadImageApp() {
try {
img = ImageIO.read(new File("C:picture.jpg"));
} catch (IOException e) {
}
}
public Dimension getPreferredSize() {
if (img == null) {
return new Dimension(100, 100);
} else {
return new Dimension(img.getWidth(null), img.getHeight(null));
}
}
}
换句话说,我想做的是使用GazeListener类的gazeUpdate()方法检测数据x1和x2,然后能够在类LoadImageApp的方法paint(Graphics g)中使用这些数据。
我还为此目的设置了设置/获取方法,但我仍然弄错了一些东西。
我做错了什么?
提前非常感谢!
在 LoadImageApp.paint
方法中,创建一个新的GazeListener
实例。您的新实例对您在其中创建的实例一无所知 main
.
解决此问题的方法是在 main
中创建final GazeListener gazeListener = new GazeListener();
,然后将其作为构造函数参数传递给app
:LoadImageApp a= new LoadImageApp(gazeListener);
。然后,将其存储为字段并从绘制中引用该字段,而不是在paint
作为附加说明,您将GazeListener和LoadImageApp称为"内部类"。它们不是内部类,而是静态成员类。如果你希望他们表现得好像他们是内部类,他们就不会。内部类允许您访问父实例的字段。您的类没有该访问权限,因为它们具有static
修饰符。
public static class LoadImageApp
extends Component {
private GazeListener gazeListener;
public LoadImageApp(GazeListener aGazeListener) {
this.gazeListener = aGazeListener;
}
...
public void paint(Graphics g) {
...
// don't do the next line
//GazeListener a = new GazeListener();
//System.out.println(a.getX1().toString()); //--> doesn't work, return an empty array
System.out.println(this.gazeListener.getX1().toString());
...
}
}
在你的 paint 方法中,你创建了一个 GazeListener 的新实例,并称之为"a"。这个"a"是空的,因为它是一个新实例,你不会向其添加任何数据。