java将数据从XML返回到UI

Question

我有一些代码在XML文件中循环，并获取<savedPositions>的每个实例。我正在尝试将每个数组中的数据添加到一个数组中，这样我就可以返回它并使用UI中的字符串-我不知道如何通过在每次单击按钮时显示<savedPositions>的每个实例将数据读回我的应用程序。这意味着我只能在文本框中显示一个<savedPositions>实例

如何使每个按钮上的文本框都更新为下一个<savedPositions>信息谢谢

我的XML：

<savedPositions>
  <savedPosition>
    <nBehaviour>nBehaviour1</nBehaviour>
    <aBehaviour>aBehaviour1</aBehaviour>
    <findings>findings1</findings>
    <forces>forces1</forces>
    <gap>gap1</gap>
    <position1>0.6488889</position1>
    <position2>-1000.0</position2>
  </savedPosition>
  <savedPosition>
    <nBehaviour>nBehaviour2</nBehaviour>
    <aBehaviour>aBehaviour2</aBehaviour>
    <findings>findings2</findings>
    <forces>aBehaviour2</forces>
    <gap>gap2</gap>
    <position1>-1000.0</position1>
    <position2>-1000.0</position2>
  </savedPosition>
</savedPositions>

读取XML代码：

public class XmlToObject {

    public static ArrayList<ArrayList<String>> main() {

        ArrayList<ArrayList<String>> obj1 = new ArrayList<ArrayList<String>>();
        ArrayList<ArrayList<String>> obj = new ArrayList<ArrayList<String>>();

        try {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            Document d = db.parse("/home/nicolas/savedPos.xml");
            XPath xp = XPathFactory.newInstance().newXPath();
            NodeList nl = (NodeList) xp.compile("//savedPosition").evaluate(d, XPathConstants.NODESET);
            System.out.println("number of saved positions " + nl.getLength());

            for (int i = 0; i < nl.getLength(); i++) {

                String a = (xp.compile("./nBehaviour").evaluate(nl.item(i)));
                String b = (xp.compile("./aBehaviour").evaluate(nl.item(i)));
                String c = (xp.compile("./gap").evaluate(nl.item(i)));
                String d1 = (xp.compile("./forces").evaluate(nl.item(i)));
                String e = (xp.compile("./findings").evaluate(nl.item(i)));
                String f = (xp.compile("./position1").evaluate(nl.item(i)));
                String g = (xp.compile("./position2").evaluate(nl.item(i)));

                ArrayList<String> savedPosition = new ArrayList<String>();
                savedPosition.add(a);
                savedPosition.add(b);
                savedPosition.add(c);
                savedPosition.add(d1);
                savedPosition.add(e);
                savedPosition.add(f);
                savedPosition.add(g);

                obj.add(savedPosition);

            }

            return obj;

        } catch (Exception l) {
            System.out.println(l.getMessage());
        }

        return obj1;
    }
}

单击按钮时调用XML：

load.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {

        ArrayList<ArrayList<String>> obj = XmlToObject.main();

        for(ArrayList<String> r: obj){
            for(int i = 0; i < r.size(); i++){
                System.out.println(r.get(i) + "");
            }
            textArea.setText(r.get(0));
            textArea1.setText(r.get(1));
            textArea2.setText(r.get(2));
            textArea3.setText(r.get(3));
            textArea4.setText(r.get(4));
            mediaPlayerComponent.getMediaPlayer().setPosition(Float.parseFloat(r.get(5)));
            mediaPlayerComponent2.getMediaPlayer().setPosition(Float.parseFloat(r.get(6)));
        }
    }
});

Answer 1

只解析XML文件一次，并声明一个整数以跟踪当前显示的位置

    List<List<String>> obj = XmlToObject.main();
    int displayedPositionIndex = 0;

然后在ActionListener上，增加计数器并显示下一个位置

load.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        displayedPositionIndex++;
        if(displayedPositionIndex >= obj.size()) {
            displayedPositionIndex = 0; // to loop back to first after last position
        }
        setPosition(displayedPositionIndex);
    }
});

我用这种实用的方法使事情更清楚

private void setPosition(int index) {
    List<String> positionData = obj.get(index);
    textArea.setText(positionData.get(0));
    textArea1.setText(positionData.get(1));
    textArea2.setText(positionData.get(2));
    textArea3.setText(positionData.get(3));
    textArea4.setText(positionData.get(4));
    mediaPlayerComponent.getMediaPlayer().setPosition(Float.parseFloat(positionData.get(5)));
    mediaPlayerComponent2.getMediaPlayer().setPosition(Float.parseFloat(positionData.get(6)));
}

注意

在XmlToObject中，使用List<List<String>>比使用ArrayList<ArrayList<String>>更好（如果可以，请始终使用接口）：

class XmlToObject {

    public static List<List<String>> main() {
        List<List<String>> positions = new ArrayList<>();

        try {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            Document d = db.parse("/path/to/savedPos.xml");
            XPath xp = XPathFactory.newInstance().newXPath();

            NodeList nl = (NodeList) xp.compile("//savedPosition").evaluate(d, XPathConstants.NODESET);
            System.out.println("number of saved positions " + nl.getLength());

            for (int i = 0; i < nl.getLength(); i++) {
                String a = (xp.compile("./nBehaviour").evaluate(nl.item(i)));
                String b = (xp.compile("./aBehaviour").evaluate(nl.item(i)));
                String c = (xp.compile("./gap").evaluate(nl.item(i)));
                String d1 = (xp.compile("./forces").evaluate(nl.item(i)));
                String e = (xp.compile("./findings").evaluate(nl.item(i)));
                String f = (xp.compile("./position1").evaluate(nl.item(i)));
                String g = (xp.compile("./position2").evaluate(nl.item(i)));

                List<String> savedPosition = Arrays.asList(a, b, c, d1, e, f, g);
                positions.add(savedPosition);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return positions;
    }
}