我想使用此URL的SAX创建xml解析
http://news.google.com/?output=rss
但是我收到了错误，请检查并告诉我错误的地方或者我的问题是否有其他解决方案。
我在此行的GoogleNewsSaxActivity.class中收到错误
for (int i = 0; i < baseParserData.getTitle().size(); i++) {
我的代码如下所示。
GoogleNewsSaxActivity.class
public class GoogleNewsSaxActivity extends Activity {
BaseFeedParser baseParserData;
ArrayList<HashMap<String, String>> items = new ArrayList<HashMap<String, String>>();
private myAdapter rssadaptor = null;
ListView lview;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
try {
SAXParserFactory saxPF = SAXParserFactory.newInstance();
SAXParser saxP = saxPF.newSAXParser();
XMLReader xmlR = saxP.getXMLReader();
URL url = new URL("http://news.google.com/?output=rss");
RssHandler myXMLHandler = new RssHandler();
xmlR.setContentHandler(myXMLHandler);
xmlR.parse(new InputSource(url.openStream()));
} catch (Exception e) {
System.out.println(e);
}
baseParserData = RssHandler.baseParserData;
/**
* Run a for loop to set All the TextViews with text until
* the size of the array is reached.
*
**/
for (int i = 0; i < baseParserData.getTitle().size(); i++) {
System.out.println("value of i==============>" + i);
HashMap<String, String> map = new HashMap<String, String>();
map.put("title", baseParserData.getTitle().get(i));
//map.put("Artist", baseParserData.getArtist().get(i));
//map.put("Contry", baseParserData.getCountry().get(i));
items.add(map);
rssadaptor = new myAdapter(GoogleNewsSaxActivity.this, items);
}
lview = (ListView) findViewById(R.id.listView);
// Getting adapter by passing xml data ArrayList
rssadaptor = new myAdapter(this, items);
lview.setAdapter(rssadaptor);
}
}
RssHandler.class
public class RssHandler extends DefaultHandler{
/*private List<BaseFeedParser> messages;
//private Message currentMessage;
private StringBuilder builder;*/
String elementValue = null;
Boolean elementOn = false;
public static BaseFeedParser baseParserData = null;
public static BaseFeedParser getBaseParserData() {
return baseParserData;
}
public static void setBaseParserData(BaseFeedParser baseParserData) {
RssHandler.baseParserData = baseParserData;
}
/*public List<BaseFeedParser> getMessages(){
return this.messages;
}*/
@Override
public void startElement(String uri, String localName, String name,
Attributes attributes) throws SAXException {
elementOn = true;
System.out.println("Hello this is startElement : =========>");
if (localName.equals(BaseFeedParser.CHANNEL))
{
baseParserData = new BaseFeedParser();
} else if (localName.equals(BaseFeedParser.ITEM)) {
}
}
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
if (elementOn) {
elementValue = new String(ch, start, length);
elementOn = false;
}
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
elementOn = false;
/**
* Sets the values after retrieving the values from the XML tags
* */
if (localName.equalsIgnoreCase(BaseFeedParser.TITLE))
baseParserData.setTitle(elementValue);
else if (localName.equalsIgnoreCase(BaseFeedParser.LINK))
baseParserData.setLink(elementValue);
else if (localName.equalsIgnoreCase(BaseFeedParser.PUB_DATE))
baseParserData.setPubDate(elementValue);
else if (localName.equalsIgnoreCase(BaseFeedParser.DESCRIPTION))
baseParserData.setDescription(elementValue);
}
}
还有另外两个类BaseFeedParser.class和myAdapter.class，BaseFeedParser类包含Getters / Setters元文件，myadapter是自定义列表视图的适配器类。
感谢。
在LOGCAT中显示错误
05-31 09:42:25.693: I/System.out(279): java.net.SocketException: Permission denied
05-31 09:42:25.713: D/AndroidRuntime(279): Shutting down VM
05-31 09:42:25.713: W/dalvikvm(279): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
05-31 09:42:25.752: E/AndroidRuntime(279): FATAL EXCEPTION: main
05-31 09:42:25.752: E/AndroidRuntime(279): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rahul.android.sax/com.rahul.android.sax.GoogleNewsSaxActivity}: java.lang.NullPointerException
05-31 09:42:25.752: E/AndroidRuntime(279): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
05-31 09:42:25.752: E/AndroidRuntime(279): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
05-31 09:42:25.752: E/AndroidRuntime(279): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
05-31 09:42:25.752: E/AndroidRuntime(279): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
05-31 09:42:25.752: E/AndroidRuntime(279): at android.os.Handler.dispatchMessage(Handler.java:99)
05-31 09:42:25.752: E/AndroidRuntime(279): at android.os.Looper.loop(Looper.java:123)
05-31 09:42:25.752: E/AndroidRuntime(279): at android.app.ActivityThread.main(ActivityThread.java:4627)
05-31 09:42:25.752: E/AndroidRuntime(279): at java.lang.reflect.Method.invokeNative(Native Method)
05-31 09:42:25.752: E/AndroidRuntime(279): at java.lang.reflect.Method.invoke(Method.java:521)
05-31 09:42:25.752: E/AndroidRuntime(279): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-31 09:42:25.752: E/AndroidRuntime(279): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-31 09:42:25.752: E/AndroidRuntime(279): at dalvik.system.NativeStart.main(Native Method)
05-31 09:42:25.752: E/AndroidRuntime(279): Caused by: java.lang.NullPointerException
05-31 09:42:25.752: E/AndroidRuntime(279): at com.rahul.android.sax.GoogleNewsSaxActivity.onCreate(GoogleNewsSaxActivity.java:61)
05-31 09:42:25.752: E/AndroidRuntime(279): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-31 09:42:25.752: E/AndroidRuntime(279): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
05-31 09:42:25.752: E/AndroidRuntime(279): ... 11 more
答案 0 :(得分：1)
使用以下代码。
SitesList.java
public class SitesList {
/** Variables */
private ArrayList<String> name = new ArrayList<String>();
private ArrayList<String> website = new ArrayList<String>();
private ArrayList<String> pubdate = new ArrayList<String>();
private ArrayList<String> desc = new ArrayList<String>();
/**
* In Setter method default it will return arraylist change that to add
*/
public ArrayList<String> getName() {
return name;
}
public void setName(String name) {
this.name.add(name);
}
public ArrayList<String> getWebsite() {
return website;
}
public void setWebsite(String website) {
this.website.add(website);
}
public ArrayList<String> getPubdate() {
return pubdate;
}
public void setPubdate(String pubdate) {
this.pubdate.add(pubdate);
}
public ArrayList<String> getDesc() {
return desc;
}
public void setDesc(String desc) {
this.desc.add(desc);
}
}
MyXMLHandler.java
public class MyXMLHandler extends DefaultHandler {
Boolean currentElement = false;
String currentValue = null;
public static SitesList sitesList = null;
public static SitesList getSitesList() {
return sitesList;
}
public static void setSitesList(SitesList sitesList) {
MyXMLHandler.sitesList = sitesList;
}
/**
* Called when tag starts ( ex:- <name>AndroidPeople</name> -- <name> )
*/
@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
currentElement = true;
if (localName.equals("channel")) {
/** Start */
sitesList = new SitesList();
}
}
/**
* Called when tag closing ( ex:- <name>AndroidPeople</name> -- </name> )
*/
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
currentElement = false;
/** set value */
if (localName.equalsIgnoreCase("title")) {
sitesList.setName(currentValue);
} else if (localName.equalsIgnoreCase("link")) {
sitesList.setWebsite(currentValue);
} else if (localName.equalsIgnoreCase("pubDate")) {
sitesList.setPubdate(currentValue);
} else if (localName.equalsIgnoreCase("description")) {
sitesList.setDesc(currentValue);
}
}
/**
* Called to get tag characters ( ex:- <name>AndroidPeople</name> -- to get
* AndroidPeople Character )
*/
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
if (currentElement) {
currentValue = new String(ch, start, length);
currentElement = false;
}
}
}
MainActivity.java
public class MainActivity extends Activity {
SitesList sitesList = null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/** Create a new layout to display the view */
LinearLayout layout = new LinearLayout(this);
layout.setOrientation(1);
/** Create a new textview array to display the results */
TextView name[];
TextView website[];
TextView pubdate[];
TextView desc[];
try {
/** Handling XML */
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
XMLReader xr = sp.getXMLReader();
/** Send URL to parse XML Tags */
URL sourceUrl = new URL(
"http://news.google.com/?output=rss");
/** Create handler to handle XML Tags ( extends DefaultHandler ) */
MyXMLHandler myXMLHandler = new MyXMLHandler();
xr.setContentHandler(myXMLHandler);
xr.parse(new InputSource(sourceUrl.openStream()));
} catch (Exception e) {
System.out.println("XML Pasing Exception = " + e);
}
/** Get result from MyXMLHandler SitlesList Object */
sitesList = MyXMLHandler.sitesList;
/** Assign textview array lenght by arraylist size */
name = new TextView[sitesList.getName().size()];
website = new TextView[sitesList.getWebsite().size()];
pubdate = new TextView[sitesList.getPubdate().size()];
desc = new TextView[sitesList.getDesc().size()];
System.out.println("Hello Name size is:- " +sitesList.getName().size());
System.out.println("Hello website size is:- " +sitesList.getWebsite().size());
System.out.println("Hello pubdate size is:- " +sitesList.getPubdate().size());
System.out.println("Hello desc size is:- " +sitesList.getDesc().size());
/** Set the result text in textview and add it to layout */
for (int i = 0; i < sitesList.getName().size(); i++) {
name[i] = new TextView(this);
name[i].setText("Name is = " + sitesList.getName().get(i));
website[i] = new TextView(this);
website[i].setText("Link is = " + sitesList.getWebsite().get(i));
layout.addView(name[i]);
layout.addView(website[i]);
}
/** Set the result text in textview and add it to layout */
for (int i = 0; i < sitesList.getPubdate().size(); i++) {
pubdate[i] = new TextView(this);
pubdate[i].setText("Pub date is = "
+ sitesList.getPubdate().get(i));
desc[i] = new TextView(this);
desc[i].setText("Desc is = "
+ sitesList.getDesc().get(i));
layout.addView(pubdate[i]);
layout.addView(desc[i]);
}
/** Set the layout view to display */
setContentView(layout);
}
}