Question

我需要在ShowNews活动中显示新闻的描述，我使用了意图并添加额外的方法将描述传递给ShowNews Activity，其中包含用于设置Description的textview。我的代码出了什么问题？

public class Downloader extends AsyncTask<Void,Void,Object> {
Context c;
String urlAddress ;
ListView lv;
ProgressDialog pd;
public Downloader(Context c,String urlAddress,ListView lv)
{
    this.c = c;
    this.urlAddress =urlAddress;
    this.lv = lv;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
    pd = new ProgressDialog(c);
    pd.setTitle("Fetching Data");
    pd.setMessage("Fetchinf Data...please wait ");
    pd.show();
}

@Override
protected Object doInBackground(Void... voids) {

    return this.downloadData();
}

@TargetApi(Build.VERSION_CODES.CUPCAKE)
@Override
protected void onPostExecute(Object data) {
    super.onPostExecute(data);
    pd.dismiss();
    if (data.toString().startsWith("Error"))
    {
        Toast.makeText(c,data.toString(),Toast.LENGTH_LONG).show();
    }
    else {
        // parsing
        new ReadRss(c, (InputStream) data,lv).execute();
    }
}
private Object downloadData()
{
    Object connection = Connector.connect(urlAddress);
    if (connection.toString().startsWith("Error"))
    {
        return connection.toString();
    }
    try {
        HttpURLConnection con = (HttpURLConnection) connection;
        int responsecode = con.getResponseCode();
        if (responsecode == con.HTTP_OK) {
            InputStream    is = new BufferedInputStream(con.getInputStream());
            return is;
        }
        return ErrorTracer.RESPONSE_ERROR+con.getResponseMessage();
    } catch (IOException e) {
        e.printStackTrace();
        return ErrorTracer.IO_ERROR;
    }
}
}




 public class ReadRss extends AsyncTask<Void,Void,Boolean> {
Context c;
InputStream is;
ListView lv;
ProgressDialog pd;
CustomAdapter adapter  ;
ArrayList<Site> sites = new ArrayList<>();
public ReadRss(Context c,InputStream is,ListView lv)
{
    this.c = c;
    this.is =is;
    this.lv = lv;
}
@Override
protected void onPreExecute() {
    super.onPreExecute();
    pd = new ProgressDialog(c);
    pd.setTitle("parsing Data");
    pd.setMessage("parsing Data...please wait ");
    pd.show();
}
@Override
protected Boolean doInBackground(Void... voids) {
    return this.parseRss();
}
@Override
protected void onPostExecute(Boolean isparsed) {
    super.onPostExecute(isparsed);
    pd.dismiss();
    if (isparsed)
    {
        //bind
        lv.setAdapter(new CustomAdapter(c,sites));
    }
    else {
        Toast.makeText(c,"Unable to parse",Toast.LENGTH_LONG).show();
    }
}
private Boolean parseRss()
{
    try {
        XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
        XmlPullParser parser = factory.newPullParser();
        parser.setInput(is,null);
        int event = parser.getEventType();
        String value = null;
        sites.clear();
        Site site = new Site();
        do {
            String name = parser.getName();
            switch (event)
            {
                case XmlPullParser.START_TAG:
                    if (name.equals("item"))
                    {
                        site = new Site();
                    }
                    break;
                case XmlPullParser.TEXT:
                    value = parser.getText();
                    break;
                case XmlPullParser.END_TAG:
                    if (name.equals("title"))
                    {
                        site.setTitle(value);
                    }else if (name.equals("description"))
                    {
                        site.setDescription(value);
                    }else if (name.equals("pubDate"))
                    {
                        site.setData(value);
                    }else if (name.equals("link"))
                    {
                        site.setLink(value);
                    }
                    if (name.equals("item"))
                    {
                        sites.add(site);
                    }
                    break;
            }
            event = parser.next();
        }while (event!=XmlPullParser.END_DOCUMENT);
        return true;
    } catch (XmlPullParserException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return false;
}
}

 public class CustomAdapter extends BaseAdapter {
Context c;
ArrayList<Site> sites;
public CustomAdapter(Context c,ArrayList<Site> sites)
{
    this.c = c;
    this.sites = sites;
}
@Override
public int getCount() {
    return sites.size();
}
@Override
public Object getItem(int i) {
    return sites.get(i);
}
@Override
public long getItemId(int i) {
    return i;
}
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
    if (view==null)
    {
        view = LayoutInflater.from(c).inflate(R.layout.row,viewGroup,false);
    }
    TextView titletxt  = (TextView) view.findViewById(R.id.textView);
    TextView desctxt  = (TextView) view.findViewById(R.id.textView2);
    TextView datetxt  = (TextView) view.findViewById(R.id.textView3);
    Site site = (Site) this.getItem(i);
    titletxt.setText(site.getTitle());
    desctxt.setText(site.getDescription());
    datetxt.setText(site.getData());
    return view;
}
}

 public class MainActivity extends AppCompatActivity {
String ulrAddress = "http://www.alahlytv.net/Rss_Feeds.aspx";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    final ListView lv = (ListView) findViewById(R.id.lv);
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
            Intent intent = new Intent(MainActivity.this,ShowNews.class);
            Site site = new Site();
            intent.putExtra("one",site.getDescription());
            startActivity(intent);

        }
    });
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            new Downloader(MainActivity.this,ulrAddress,lv).execute();
        }
    });
public class ShowNews extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_show_news);
    TextView textView = (TextView) findViewById(R.id.textView4);
    Intent intent = getIntent();
    Bundle bd = intent.getExtras();
    if(bd != null)
    {
        String getName = (String) bd.get("one");
        textView.setText(getName);
    }
}
}

Answer 1

当您在intent中添加任何额外内容时，请勿尝试从Bundle获取该内容。因此，将您的阅读传递数据代码更改为：

    Intent intent = getIntent();
    String getName = intent.getStringExtra("one", "default_value_if_null");
    textView.setText(getName);

Answer 2

像这样更改您的代码

Intent intent = getIntent();
    if(intent != null)
    {
        String getName = intent.getExtras().getString("one");
        textView.setText(getName);
    }

显示其他活动中新闻的说明

2 个答案: