Question

我为孩子制作了一个小型测试程序。我想学习他的数学。面对从XML文件读取问题的问题

<?xml version="1.0" encoding="utf-8"?>
    <questions>
    <question>
        <vopros>How much will 2+2?</vopros>
        <otvet_1>2</otvet_1>
        <otvet_2>6</otvet_2>
        <otvet_3>8</otvet_3>
        <otvet_4  name="pravilno">4</otvet_4>
    </question>
    <question>
        <vopros>How much will 3+3?</vopros>
        <otvet_1>12</otvet_1>
        <otvet_2>16</otvet_2>
        <otvet_3>18</otvet_3>
        <otvet_4  name="pravilno">6</otvet_4>
    </question>
    <question>
        <vopros>How much is 4+4?</vopros>
        <otvet_1>22</otvet_1>
        <otvet_2>26</otvet_2>
        <otvet_3>18</otvet_3>
        <otvet_4  name="pravilno">8</otvet_4>
    </question>
    <question>
        <vopros>How much is 5+5?</vopros>
        <otvet_1>2</otvet_1>
        <otvet_2>6</otvet_2>
        <otvet_3>8</otvet_3>
        <otvet_4  name="pravilno">10</otvet_4>
    </question>
</questions>

我需要激活vopros3并回答选项（otvet_1，otvet_2，otvet_3，otvet_4）

从XML文件检索数据的Java代码

try {
    XmlPullParser parser = getResources().getXml(R.xml.voprosi);

    while (parser.getEventType() != XmlPullParser.END_DOCUMENT) {
        if (parser.getEventType() == XmlPullParser.START_TAG
                && parser.getName().equals("question")) {

            if(numvopr==3)
            {
                // ....... here it is necessary to withdraw a question and answers

                Question.setText(...);
                answ1.setText(...);
                answ2.setText(...);
                answ3.setText(...);
                answ4.setText(...);
            }
            numvopr++;
        }
        parser.next();
    }
} catch (Throwable t) {
    Toast.makeText(this,
            "XML Error: " + t.toString(),
            Toast.LENGTH_LONG).show();
}

Answer 1

实现为状态机的一种方法：

String lastStartTag = "";

// change to desired question - 0-based
int targetQuestion = 3;

while (parser.getEventType() != XmlPullParser.END_DOCUMENT) {

    // Count questions and record every START tag
    if (parser.getEventType() == XmlPullParser.START_TAG) {
        lastStartTag = parser.getName();
        if (parser.getName().equals("question")) {
            numvopr++;
        }
    }

    // Process text based on whether we are at desired question
    // and last processed START tag.
    else if (parser.getEventType() == XmlPullParser.TEXT) {

        if (numvopr == targetQuestion) {

            if (lastStartTag.compareTo("vopros") == 0) {
                Question.setText(parser.getText());
            }

            else if (lastStartTag.compareTo("otvet_1") == 0) {
                answ1.setText(parser.getText());
            }
            else if (lastStartTag.compareTo("otvet_2") == 0) {
                answ2.setText(parser.getText());
            }
            else if (lastStartTag.compareTo("otvet_3") == 0) {
                answ3.setText(parser.getText());
            }
            else if (lastStartTag.compareTo("otvet_4") == 0) {
                answ4.setText(parser.getText());
            }
        }
    }

    parser.next();
}

Answer 2

与switch语句的实现略有不同。

int numOfQuestions = 0;
String text = null;
try {
    XmlPullParser parser = getResources().getXml(R.xml.test);
    while (parser.getEventType() != XmlPullParser.END_DOCUMENT) {
        String elementName = parser.getName();

        switch (parser.getEventType()) {
            case XmlPullParser.START_TAG:
                if ("question".equals(elementName)) {
                    numOfQuestions++;
                }
                break;
            case XmlPullParser.TEXT:
                text = parser.getText();
                break;
            case XmlPullParser.END_TAG:
                if (numOfQuestions == 3) {
                    switch (elementName) {
                        case "vopros":
                            Log.i(TAG, "Question: " + text);
                            break;
                        case "otvet_1":
                            Log.i(TAG, "answ1: " + text);
                            break;
                        case "otvet_2":
                            Log.i(TAG, "answ2: " + text);
                            break;
                        case "otvet_3":
                            Log.i(TAG, "answ3: " + text);
                            break;
                        case "otvet_4":
                            Log.i(TAG, "answ4: " + text);
                            break;
                        default:
                            break;
                    }
                }
                break;
            default:
                break;
        }
        parser.next();
    }
} catch (Throwable t) {
    Log.e(TAG, "Problem while parsing the xml.", t);
}

如何从XML文件中选择特定元素？

2 个答案: