Java 如何从另一个类访问变量？索爱手机应用开发职位

花了几个小时试图弄清楚为什么“下载程序”“类无法读取获取”方法中的“finalURL”变量？非常感谢任何提示

这是一个词汇表改进应用程序，因此它从字典api获取XML数据

public class DefineWord extends Activity {

    static final String head = new String("http://www.dictionaryapi.com/api/v1/references/collegiate/xml/");
    static final String apikey = new String("?key=xxxxxx-xxx-xxx-xxxx-xxxxx");

    TextView src;
    EditText searchBar;

OnCreate:

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.defineword);

        src=(TextView)findViewById(R.id.textFromWeb);
        searchBar = (EditText)findViewById(R.id.searchBar);
    }

    public void fetch(View v){                                              //onClick in xml starts this "fetch" method

        String w = searchBar.getText().toString();                          // get the text the user enters into searchbar
        String finalURL = head.trim() + w.trim() + apikey.trim();           //concatenate api url 

        Downloader d = new Downloader(); 
        d.execute(finalURL);                                                // Calls AsyncTask to connect in the background.    
}

    class Downloader extends AsyncTask<String,Void,String>{

        ArrayList<String> information = new ArrayList<String>();    // Store fetched XML data in ArrayList

        public String doInBackground(String... urls) {
            String result = null;

            try {

                DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                DocumentBuilder builder = factory.newDocumentBuilder();

获取方法：

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.defineword);

        src=(TextView)findViewById(R.id.textFromWeb);
        searchBar = (EditText)findViewById(R.id.searchBar);
    }

    public void fetch(View v){                                              //onClick in xml starts this "fetch" method

        String w = searchBar.getText().toString();                          // get the text the user enters into searchbar
        String finalURL = head.trim() + w.trim() + apikey.trim();           //concatenate api url 

        Downloader d = new Downloader(); 
        d.execute(finalURL);                                                // Calls AsyncTask to connect in the background.    
}

    class Downloader extends AsyncTask<String,Void,String>{

        ArrayList<String> information = new ArrayList<String>();    // Store fetched XML data in ArrayList

        public String doInBackground(String... urls) {
            String result = null;

            try {

                DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                DocumentBuilder builder = factory.newDocumentBuilder();

异步任务：

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.defineword);

        src=(TextView)findViewById(R.id.textFromWeb);
        searchBar = (EditText)findViewById(R.id.searchBar);
    }

    public void fetch(View v){                                              //onClick in xml starts this "fetch" method

        String w = searchBar.getText().toString();                          // get the text the user enters into searchbar
        String finalURL = head.trim() + w.trim() + apikey.trim();           //concatenate api url 

        Downloader d = new Downloader(); 
        d.execute(finalURL);                                                // Calls AsyncTask to connect in the background.    
}

    class Downloader extends AsyncTask<String,Void,String>{

        ArrayList<String> information = new ArrayList<String>();    // Store fetched XML data in ArrayList

        public String doInBackground(String... urls) {
            String result = null;

            try {

                DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                DocumentBuilder builder = factory.newDocumentBuilder();

类下载程序扩展异步任务{
ArrayList information=new ArrayList（）；//将获取的XML数据存储在ArrayList中
公共字符串doInBackground（字符串…URL）{
字符串结果=null；
试一试{
DocumentBuilderFactory工厂=DocumentBuilderFactory.newInstance（）；
DocumentBuilder=factory.newDocumentBuilder（）；

问题就在这里。“finalURL”无法解析为变量

                Document doc = builder.parse(finalURL);  //finalURL cannot be resolved to a variable ??? 

                doc.getDocumentElement().normalize();

                NodeList nList = doc.getElementsByTagName("entry"); // Make a list of all elements in XML file with tag name "entry" 

                for (int temp = 0; temp < nList.getLength(); temp++) {   //Iterate over elements and get their attributes (Definition, etymology...)  

                    Node nNode = nList.item(temp);

                    if (nNode.getNodeType() == Node.ELEMENT_NODE){


                        Element eElement = (Element) nNode;

                        String element = ("\nCurrent Element : " + eElement.getAttribute("id"));
                        information.add(element);  //

                        String definitions = ("\nDefinition : \n" + eElement.getElementsByTagName("dt").item(0).getTextContent());
                        information.add(definitions);
                    }

                }

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

            }catch(SAXException e){
                e.printStackTrace();
            }catch(IOException e){
                e.printStackTrace();
            }

            return result;
        }

        protected void onPostExecute (String result){

            String finalresult = information.toString();
            src.setText(finalresult);
        }

    }
}

Document doc=builder.parse（finalURL）；//finalURL无法解析为变量？？？
doc.getDocumentElement（）.normalize（）；
NodeList nList=doc.getElementsByTagName（“entry”）；//列出XML文件中标记名为“entry”的所有元素
对于（int-temp=0；temp

---

谢谢你抽出时间

这称为参数。通过使用

asyncTask.execute（参数）

将对象传递到

doInBackground（String…arrayOfParameters）

---

因此，要再次访问该值，应该使用

builder.parse（URL[0]）
finalURL在fetch方法中声明，因此只能在此函数中访问

如果您希望它在整个程序中都可以访问，请在函数外部声明它，如下所示

class MyClass{
    public static String finalURL;    // variable declaration

    public void fetch(View v){ 
        finalURL = head.trim() + w.trim() + apikey.trim();   // variable assignment
    }    

    public void otherFunction(){
        Document doc = builder.parse(finalURL);    // retrieves static class variable
    }
}

我希望这能回答你的问题。如果没有，请告诉我混淆的是什么。
哇！非常感谢你。我真不敢相信会那么容易。哈哈，我希望你有一个伟大的一天。荣誉