如何将数据从XML文件添加到ArrayList

Question

this is for an Android application, I have an XML file that I would like to read named 'categories.xml':

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
<categories>
  <category>
    <name>Simulator Commands</name>
    <id>1</id>
  </category>
  <category>
    <name>Control Surface Commands</name>
    <id>2</id>
  </category>
  <category>
    <name>Control Surface Commands</name>
    <id>3</id>
  </category>
  <category>
    <name>General Aircraft Commands</name>
    <id>4</id>
  </category>
  <category>
    <name>Light Commands</name>
    <id>5</id>
  </category>
  <category>
    <name>Radio Commands</name>
    <id>6</id>
  </category>
  <category>
    <name>Autopilot Commands</name>
    <id>7</id>
  </category>
  <category>
    <name>Intrument Commands</name>
    <id>8</id>
  </category>
  <category>
    <name>View Commands</name>
    <id>9</id>
  </category>
  <category>
    <name>Slew Keys</name>
    <id>10</id>
  </category>
  <category>
    <name>Mission Commands</name>
    <id>11</id>
  </category>
  <category>
    <name>Multiplayer Commands</name>
    <id>12</id>
  </category>
  <category>
    <name>C172 Intrument Panels</name>
    <id>13</id>
  </category>
  <category>
    <name>BE58 Intrument Panels</name>
    <id>14</id>
  </category>
</categories>

And I would like to add the text from tag to an ArrayList named 'categorys'. I've tried this:

ArrayList<String> categorys = new ArrayList<String>();
        categorys.add("Please select a category");
        //START ADDING HERE
        XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
        factory.setNamespaceAware(true);
        XmlPullParser parser = factory.newPullParser();
        File file = new File(Environment.getExternalStorageDirectory()+ "/fsx_kneeboard/categories.xml");
        FileInputStream fis = new FileInputStream(file);
        parser.setInput(new InputStreamReader(fis));
        parser.next();
        int eventType = parser.getEventType();
        int Categories = 0;
        while (eventType != XmlPullParser.END_DOCUMENT) {
            if (eventType == XmlPullParser.START_TAG) {
                Categories++;
            } if (eventType == XmlPullParser.START_TAG && Categories == 1) {
                Categories++;
            } if (eventType == XmlPullParser.START_TAG && Categories == 2) {
                categorys.add(parser.getText());
            }
            parser.next();
        }

But something in this part:

while (eventType != XmlPullParser.END_DOCUMENT) {
                if (eventType == XmlPullParser.START_TAG) {
                    Categories++;
                } if (eventType == XmlPullParser.START_TAG && Categories == 1) {
                    Categories++;
                } if (eventType == XmlPullParser.START_TAG && Categories == 2 && parser.getName.equals("name")) {
                    categorys.add(parser.getText());
                }
                parser.next();
            }

Make it force close, I'm sure it's this part the error is in because if I remove it it will not force close and will only add "Please select a command" to the ArrayList.

Thanks for your time and help, zeokila

Answer 1

The key is going to be this line...

    int eventType = parser.getEventType();

...because it is outside the while {...} loop and it is never changing.

That means the while condition eventType != XmlPullParser.END_DOCUMENT will never be false so you end up repeatedly calling parser.next() forcing it to past end-of-file probably causing an exception.

    int eventType = parser.getEventType();
    int Categories = 0;
    while (eventType != XmlPullParser.END_DOCUMENT) {
        if (eventType == XmlPullParser.START_TAG) {
            Categories++;
        } if (eventType == XmlPullParser.START_TAG && Categories == 1) {
            Categories++;
        } if (eventType == XmlPullParser.START_TAG && Categories == 2) {
            categorys.add(parser.getText());
        }
        parser.next();
    }

You need to update eventType after each call to parser.next() and I suspect you'd also want to reset Categories to 0 after each call to categorys.add(...)