我的应用在模拟器中运行正常，但在我的手机中没有运行（lg nexus 4） - “我的应用停止工作”。 我的一般目的是显示url xml的问题 - 答案（数据） 在LogCat中显示以下内容：
12-17 12:30:13.401: E/AndroidRuntime(10251): FATAL EXCEPTION: main
12-17 12:30:13.401: E/AndroidRuntime(10251): Process: com.michalakis.schoolgame, PID: 10251
12-17 12:30:13.401: E/AndroidRuntime(10251): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.michalakis.schoolgame/com.michalakis.schoolgame.StartGame}: java.lang.NullPointerException
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.app.ActivityThread.access$800(ActivityThread.java:135)
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.os.Handler.dispatchMessage(Handler.java:102)
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.os.Looper.loop(Looper.java:136)
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.app.ActivityThread.main(ActivityThread.java:5017)
12-17 12:30:13.401: E/AndroidRuntime(10251): at java.lang.reflect.Method.invokeNative(Native Method)
12-17 12:30:13.401: E/AndroidRuntime(10251): at java.lang.reflect.Method.invoke(Method.java:515)
12-17 12:30:13.401: E/AndroidRuntime(10251): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
12-17 12:30:13.401: E/AndroidRuntime(10251): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
12-17 12:30:13.401: E/AndroidRuntime(10251): at dalvik.system.NativeStart.main(Native Method)
12-17 12:30:13.401: E/AndroidRuntime(10251): Caused by: java.lang.NullPointerException
12-17 12:30:13.401: E/AndroidRuntime(10251): at com.michalakis.schoolgame.StartGame.init(StartGame.java:75)
12-17 12:30:13.401: E/AndroidRuntime(10251): at com.michalakis.schoolgame.StartGame.onCreate(StartGame.java:39)
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.app.Activity.performCreate(Activity.java:5231)
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
12-17 12:30:13.401: E/AndroidRuntime(10251): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
我的java avtivity如下：
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.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class StartGame extends Activity {
private int CurrentQuestion;
private Button answerButton;
private Button questionButton;
private TextView questionView;
private TextView answerView;
private EditText answerText;
TextView[] Question;
TextView[] id;
TextView[] Answer;
/** Create Object For SiteList Class */
SitesList sitesList = null;
/** Called when the activity is first created. */
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
init();
}
public void init(){
CurrentQuestion = -1;
answerButton = (Button)findViewById(R.id.AnswerButton);
questionButton = (Button)findViewById(R.id.QuestionButton);
questionView = (TextView)findViewById(R.id.QuestionTextView);
answerView = (TextView)findViewById(R.id.AnswerTextView);
answerText = (EditText)findViewById(R.id.AnswerText);
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://eclass.sch.gr/modules/document/file.php/T489110/quiz.xml");
/** 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 Excpetion = " + e);
}
/** Get result from MyXMLHandler SitlesList Object */
sitesList = MyXMLHandler.sitesList;
/** Assign textview array lenght by arraylist size */
Question = new TextView[sitesList.getQuestion().size()];
id = new TextView[sitesList.getQuestion().size()];
Answer = new TextView[sitesList.getQuestion().size()];
answerButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
checkAnswer();
}});
questionButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
showQuestion();
}});
}
public void showQuestion(){
CurrentQuestion++;
if (CurrentQuestion == sitesList.getQuestion().size())
CurrentQuestion = 0;
questionView.setText(sitesList.getQuestion().get(CurrentQuestion));
answerView.setText("");
answerText.setText("");
}
public boolean isCorrect(String answer){
return (answer.equalsIgnoreCase(sitesList.getAnswer().get(CurrentQuestion)));
}
public void checkAnswer(){
String answer = answerText.getText().toString();
if (isCorrect(answer))
answerView.setText("Σωστή Απάντηση");
else
answerView.setText("Λανθασμένη Απάντηση. Προσπαθείστε πάλι!!!");
}
}
main.xml如下：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#000000"
android:orientation="vertical"
android:padding="20dp" >
<TextView
android:id="@+id/QuestionTextView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
android:text=""
android:textColor="#FFFFFF"
android:textSize="15dp"
android:textStyle="bold" >
</TextView>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:weightSum="100"
android:padding="10dp" >
<EditText
android:id="@+id/AnswerText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:textSize="15dp"
android:textStyle="bold"
android:layout_weight="70"
android:hint="Γράψτε εδώ την απάντηση σας..." >
</EditText>
<Button
android:id="@+id/AnswerButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
android:layout_weight="30"
android:textColor="#800000"
android:textStyle="bold"
android:text="Έλεγχος Απάντησης" />
</LinearLayout>
<TextView
android:id="@+id/AnswerTextView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
android:textSize="20dp"
android:textColor="#00FF00"
android:textStyle="bold"
android:text="" />
<Button
android:id="@+id/QuestionButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textStyle="bold"
android:textSize="18dp"
android:text="Δείξτε μου την ερώτηση" />
</LinearLayout>
我期待着回答 谢谢
答案 0 :(得分：0)
第75行：
Question = new TextView[sitesList.getQuestion().size()];
因此sitesList为空，或者更可能是getQuestion()返回null。