如何將數據從XML文件添加到ArrayList

Question

這是一個Android應用程序，我有一個XML文件，我想讀取它的名稱為'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>

我想將標簽中的文本添加到名為“ categorys”的ArrayList中。 我已經試過了：

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();
        }

但是這部分內容：

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();
            }

使其強制關閉，我確定這是錯誤所在的部分，因為如果刪除它，則不會強制關閉，而只會將“請選擇命令”添加到ArrayList中。

謝謝您的時間和幫助，zeokila

Answer 1

關鍵是這條線...

    int eventType = parser.getEventType();

...因為它在while {...}循環之外，並且從未改變。

這意味着while條件eventType != XmlPullParser.END_DOCUMENT永遠不會為假，因此您最終會反復調用parser.next()強制其到達文件結尾，這可能會導致異常。

    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();
    }

您需要在每次調用parser.next()之后更新eventType ，並且我懷疑您還希望在每次調用categorys.add(...)之后將Categories重置為0 categorys.add(...)