本文介绍了Android应用程序无法启动在Android 4.0的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
好吧，我工作的一个Android应用程序，可以显示你喜欢电视节目表，新闻，水灰比预测与运势使用RSS的几件事情。这个应用程序的工作，因为它应该在Android 2.1或2.3.x版本，但是当我开始它4.0或4.1将停止工作，我选择从主任何选项之后。
Ok, I was working on a Android app that can show you a few things like TV schedule, News, Wather Forecast and Horoscope using RSS. The app works as it should on Android 2.1 or 2.3.X, but when I start it on 4.0 or 4.1 it stops working after I chose any option from main.
应用程序的结构是：
- 主
-activity对于具有一个视图具体的东西（像刚才新闻）
-Activity for specific thing (like just News) that has a view
-XML由previous类叫解析类
-XML Parser class that is called by previous class
-activity的劲儿地查看（就像从一大堆的消息只是一个信息）与它的看法
-Activity for Signle View (like just one information from whole bunch of news) with it's view
下面我公司提供的清单，日志和少数几类：
Here I provide the Manifest, Log and few classes:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.mtel.vodic"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="7"
android:targetSdkVersion="14" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".Vodic"
android:label="@string/title_activity_pocetna" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".Pomoc"
android:label="@string/m_tel_vodi_za_odlu_ne"
></activity>
<activity
android:name=".Pomocna"
android:label="@string/m_tel_vodi_za_odlu_ne"
></activity>
<activity
android:name=".SingleMenuItemActivity"
android:label="@string/m_tel_vodi_za_odlu_ne"
></activity>
.
.
.
</application>
<uses-permission android:name="android.permission.INTERNET" />
<!-- Needed to check when the network connection changes -->
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
</manifest>
错误日志：
10-18 20:35:05.457: E/Trace(730): error opening trace file: No such file or directory (2)
10-18 20:35:06.197: I/Choreographer(730): Skipped 30 frames! The application may be doing too much work on its main thread.
10-18 20:35:06.257: D/gralloc_goldfish(730): Emulator without GPU emulation detected.
10-18 20:35:11.316: D/AndroidRuntime(730): Shutting down VM
10-18 20:35:11.316: W/dalvikvm(730): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
10-18 20:35:11.347: E/AndroidRuntime(730): FATAL EXCEPTION: main
10-18 20:35:11.347: E/AndroidRuntime(730): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mtel.vodic/com.mtel.vodic.Vijesti}: java.lang.NullPointerException
10-18 20:35:11.347: E/AndroidRuntime(730): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
10-18 20:35:11.347: E/AndroidRuntime(730): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
10-18 20:35:11.347: E/AndroidRuntime(730): at android.app.ActivityThread.access$600(ActivityThread.java:130)
10-18 20:35:11.347: E/AndroidRuntime(730): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
10-18 20:35:11.347: E/AndroidRuntime(730): at android.os.Handler.dispatchMessage(Handler.java:99)
10-18 20:35:11.347: E/AndroidRuntime(730): at android.os.Looper.loop(Looper.java:137)
10-18 20:35:11.347: E/AndroidRuntime(730): at android.app.ActivityThread.main(ActivityThread.java:4745)
10-18 20:35:11.347: E/AndroidRuntime(730): at java.lang.reflect.Method.invokeNative(Native Method)
10-18 20:35:11.347: E/AndroidRuntime(730): at java.lang.reflect.Method.invoke(Method.java:511)
10-18 20:35:11.347: E/AndroidRuntime(730): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
10-18 20:35:11.347: E/AndroidRuntime(730): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-18 20:35:11.347: E/AndroidRuntime(730): at dalvik.system.NativeStart.main(Native Method)
10-18 20:35:11.347: E/AndroidRuntime(730): Caused by: java.lang.NullPointerException
10-18 20:35:11.347: E/AndroidRuntime(730): at com.mtel.vodic.Vijesti.onCreate(Vijesti.java:61)
10-18 20:35:11.347: E/AndroidRuntime(730): at android.app.Activity.performCreate(Activity.java:5008)
10-18 20:35:11.347: E/AndroidRuntime(730): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
10-18 20:35:11.347: E/AndroidRuntime(730): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
10-18 20:35:11.347: E/AndroidRuntime(730): ... 11 more
10-18 20:35:13.926: I/Process(730): Sending signal. PID: 730 SIG: 9
主营：
public class Vodic extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pocetna);
Button tv = (Button)findViewById(R.id.tv);
Button vijesti = (Button)findViewById(R.id.vijesti);
Button horoskop = (Button)findViewById(R.id.horoskop);
Button vremenska_prognoza = (Button)findViewById(R.id.vremenska_prognoza);
Button o_aplikaciji = (Button)findViewById(R.id.o_aplikaciji);
Button pomoc = (Button)findViewById(R.id.pomoc);
.
.
.
vijesti.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
Intent xw = new Intent(getApplicationContext(), Vijesti.class );
//xw.putExtra("A", "http://bih-x.info/feed/");
xw.putExtra("A", "http://klix.ba/rss/naslovnica");
if(!isOnline()) {
Toast.makeText(getApplicationContext(), "Niste povezani sa internetom!", Toast.LENGTH_SHORT).show();
} else {
startActivity(xw);
}
}
});
.
.
.
public boolean isOnline() {
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
if(netInfo != null && netInfo.isConnected()) {
return true;
}
return false;
}
}
活动：
public class Vijesti extends ListActivity {
static String url =null;
// XML node keys
static final String KEY_ITEM = "item"; // parent node
static final String KEY_TITLE = "title";
static final String KEY_DATE = "pubDate";
static final String KEY_DESC = "encoded";
static final String UVOD = "uvod";
static final String CLANAK = "clanak";
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.vijesti_m);
Intent in = getIntent();
// Get XML values from previous intent
url = in.getStringExtra("A");
final ArrayList<HashMap<String,String>> menuItems = new ArrayList<HashMap<String,String>>();
ArrayList<String> xqw = new ArrayList<String>();
ParserVijesti parser=null;
Document doc=null;
try {
parser = new ParserVijesti();
String xml = parser.getXmlFromUrl(url); //get XML
doc = parser.getDomElement(xml);
} catch (Exception e1) {
finish();
}
NodeList nl = doc.getElementsByTagName(KEY_ITEM);
//loop
for (int i=0; i< nl.getLength(); i++){
HashMap<String, String> map = new HashMap<String, String>();
HashMap<String, String> mapq = new HashMap<String, String>();
Element e = (Element) nl.item(i);
//add to map
map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
map.put(KEY_DATE, parser.getValue(e, KEY_DATE));
map.put(UVOD, parser.getValue(e,UVOD));
map.put(CLANAK, parser.getValue(e,CLANAK));
menuItems.add(map);
xqw.add(parser.getValue(e,KEY_TITLE));
}
for(int gf=0; gf<xqw.size(); gf++){
Log.w("ISPISI: ", xqw.get(gf));
}
ArrayAdapter adapterx = new ArrayAdapter(this, R.layout.vijesti_m,R.id.tetkica, xqw);
setListAdapter(adapterx);
//singleView
ListView lv = getListView();
lv.setOnItemClickListener(new OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id){
int hg = position;
HashMap<String, String> kaktus = menuItems.get(hg);
String uvod1 = kaktus.get(UVOD);
String clanak1 = kaktus.get(CLANAK);
String dat1 = kaktus.get(KEY_DATE);
String tit1 = kaktus.get(KEY_TITLE);
//intent
Intent inx = new Intent(getApplicationContext(), VijestiSingle.class);
inx.putExtra(KEY_TITLE, tit1);
inx.putExtra(KEY_DATE, dat1);
inx.putExtra(UVOD, uvod1);
inx.putExtra(CLANAK, clanak1);
startActivity(inx);
}
});
}
}
XML解析类：
XML Parsing Class:
public class ParserVijesti {
// constructor
public ParserVijesti() {
}
/**
* Getting XML from URL making HTTP request
* @param url string
* */
public String getXmlFromUrl(String url) {
String xml = null;
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
xml = EntityUtils.toString(httpEntity, "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
// return XML
return xml;
}
/**
* Getting XML DOM element
* @param XML string
* */
public Document getDomElement(String xml){
Document doc = null;
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setCoalescing(true);
dbf.setNamespaceAware(true);
try {
DocumentBuilder db = dbf.newDocumentBuilder();
InputSource is = new InputSource();
is.setByteStream(new ByteArrayInputStream(xml.getBytes("UTF-8")));
doc = db.parse(is);
} catch (ParserConfigurationException e) {
Log.e("Error: ", e.getMessage());
return null;
} catch (SAXException e) {
Log.e("Error: ", e.getMessage());
return null;
} catch (IOException e) {
Log.e("Error: ", e.getMessage());
return null;
}
return doc;
}
/** Getting node value
* @param elem element
*/
public final String getElementValue( Node elem ) {
Node child;
if( elem != null){
if (elem.hasChildNodes()){
for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
if(child.getNodeType() == Node.TEXT_NODE || child.getNodeType() == Node.CDATA_SECTION_NODE){
return child.getNodeValue();
}
}
}
}
return "";
}
public final String getElementValue2( Node elem ) {
Node child;
if( elem != null){
if (elem.hasChildNodes()){
for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
if(child.getNodeType() == Node.CDATA_SECTION_NODE){
return child.getNodeValue();
}
}
}
}
return "SRANJE";
}
/**
* Getting node value
* @param Element node
* @param key string
* */
public String getValue(Element item, String str) {
NodeList n = item.getElementsByTagName(str);
return this.getElementValue(n.item(0));
}
public String getValue3(Element item, String str){
NodeList n = item.getElementsByTagNameNS("http://purl.org/rss/1.0/modules/content/", str);
String ses = this.getElementValue2(n.item(0));
//String mim =ses.replaceAll("(?s)\\<.*?\\>", " \n");
String html = ses;
Spanned strxa = Html.fromHtml(html);
String fffx=strxa.toString();
//return this.getElementValue2(n.item(0));
//return ses;
//return Promjena(ses);
return fffx;
}
}
要总结：应用程序的工作，因为它应该在2.1或2.3.x版本，但停止后，我从主要活动在Android 4.0或4.1选择什么。我不知道这是怎么回事吧..任何人可以帮助？
To sum up: App works as it should on 2.1 or 2.3.x but stops after I chose anything from main activity on Android 4.0 or 4.1. I don't know what's up with it.. can anybody help?
推荐答案
据日志，你要对 Vijesti.java:61 空指针。你说这条线是：
According to the logs, you're getting a null pointer on Vijesti.java:61. You said this line is:
NodeList nl = doc.getElementsByTagName(KEY_ITEM);
这意味着商务部必须为空。由于分配与 getDomElement（），这意味着你的问题在于方法。我看到，它可能是空的唯一方式（因为 DocumentBuilder.parse（）不能返回null）是，如果你打你的捉语句。
That means doc must be null. Since you assign that with getDomElement(), it means your problem lies in that method. The only way I see that it could be null (since DocumentBuilder.parse() can't return null) is if you're hitting one of your catch statements.
你得到任何的捕捞在logcat中的异常信息？你给出的部分仅列出了从空指针导致的实际误差。您的留言信息将会在此之前，可能会有点。检查这一点，你就可以告诉你得到它的异常，并相应地处理它。
Do you get any of the catch exception messages in your logcat? The portion you've shown only lists the actual errors resulting from the null pointer. Your message would probably be a bit before that. Check for that, and you'll be able to tell which exception you're getting, and handle it accordingly.
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