Android 切换视图

Question

我构建了一个 RSS 阅读器，当单击列表项时，它会切换到详细视图。我在打开新视图时遇到问题。我的代码在这里：

public void onItemClick(AdapterView parent, View v, int position, long id)
 {

     //Log.i(tag,"item clicked! [" + feed.getItem(position).getTitle() + "]");      

     Intent itemintent = new Intent(this,ShowDescription.class);

     Bundle b = new Bundle();
     b.putString("title", feed.getItem(position).getTitle());
     b.putString("description", feed.getItem(position).getDescription());
     b.putString("link", feed.getItem(position).getLink());
     b.putString("pubdate", feed.getItem(position).getPubDate());

     itemintent.putExtra("android.intent.extra.INTENT", b);

 }

整个类的代码如下：

package com.CalvaryChapelMelbourne.feedparser;


import android.app.Activity;
import android.os.Bundle;
import android.view.*;
import android.widget.TextView;
import android.widget.ListView;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.AdapterView.OnItemClickListener; 
import android.util.Log;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.URL;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.InputSource;

import org.xml.sax.XMLReader;

import android.content.Intent;

import com.CalvaryChapelMelbourne.feedparser.ShowDescription;

public class RSSReader extends Activity implements OnItemClickListener
{

public final String RSSFEEDOFCHOICE = "http://app.calvaryccm.com/mobile/android/v1/devos";

public final String tag = "RSSReader";
private RSSFeed feed = null;

/** Called when the activity is first created. */

public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.main);

    // go get our feed!
    feed = getFeed(RSSFEEDOFCHOICE);

    // display UI
    UpdateDisplay();

}


private RSSFeed getFeed(String urlToRssFeed)
{
    try
    {
        // setup the url
       URL url = new URL(urlToRssFeed);

       // create the factory
       SAXParserFactory factory = SAXParserFactory.newInstance();
       // create a parser
       SAXParser parser = factory.newSAXParser();

       // create the reader (scanner)
       XMLReader xmlreader = parser.getXMLReader();
       // instantiate our handler
       RSSHandler theRssHandler = new RSSHandler();
       // assign our handler
       xmlreader.setContentHandler(theRssHandler);
       // get our data via the url class
       InputSource is = new InputSource(url.openStream());
       // perform the synchronous parse           
       xmlreader.parse(is);
       // get the results - should be a fully populated RSSFeed instance, or null on error
       return theRssHandler.getFeed();
    }
    catch (Exception ee)
    {
        // if we have a problem, simply return null
        System.out.println(ee.getMessage());
        System.out.println(ee.getStackTrace());
        System.out.println(ee.getCause());
        return null;
    }
}
public boolean onCreateOptionsMenu(Menu menu) 
{
    super.onCreateOptionsMenu(menu);
    menu.add(Menu.NONE, 0, 0, "Refresh");
    Log.i(tag,"onCreateOptionsMenu");
    return true;
}

public boolean onOptionsItemSelected(MenuItem item){
    switch (item.getItemId()) {
    case 0:

        Log.i(tag,"Set RSS Feed");
        return true;
    case 1:
        Log.i(tag,"Refreshing RSS Feed");
        return true;
    }
    return false;
}


private void UpdateDisplay()
{
    TextView feedtitle = (TextView) findViewById(R.id.feedtitle);
    TextView feedpubdate = (TextView) findViewById(R.id.feedpubdate);
    ListView itemlist = (ListView) findViewById(R.id.itemlist);


    if (feed == null)
    {
        feedtitle.setText("No RSS Feed Available");
        return;
    }

    if(feedtitle != null)
        feedtitle.setText(feed.getTitle());
    if(feedpubdate != null)
        feedpubdate.setText(feed.getPubDate());


    ArrayAdapter<RSSItem> adapter = new ArrayAdapter<RSSItem>(this,android.R.layout.simple_list_item_1,feed.getAllItems());

    itemlist.setAdapter(adapter);

    itemlist.setOnItemClickListener(this);

    itemlist.setSelection(0);

}


 public void onItemClick(AdapterView parent, View v, int position, long id)
 {

     //Log.i(tag,"item clicked! [" + feed.getItem(position).getTitle() + "]");      

     Intent itemintent = new Intent(this,ShowDescription.class);

     Bundle b = new Bundle();
     b.putString("title", feed.getItem(position).getTitle());
     b.putString("description", feed.getItem(position).getDescription());
     b.putString("link", feed.getItem(position).getLink());
     b.putString("pubdate", feed.getItem(position).getPubDate());

     itemintent.putExtra("android.intent.extra.INTENT", b);

 }

}

Answer 1

您需要在 onItemClick 方法末尾调用 startActivity(itemintent)。另外，您要切换的是“活动”，而不是“视图”。请参阅此文档和有关 UI 的文档以获得更好的理解。

Answer 2

您必须启动 ShowDescription 活动。

public void onItemClick(AdapterView parent, View v, int position, long id)  {
  ...
  startActivity(itemintent);
}