我是android的新手，我正在尝试使用数组适配器，运行方法和multi threading创建列表视图，但我收到以下错误：
07-14 19：00：15.605 29316-29316 / com.protogeo.moves.demos.apps W / dalvikvm：threadid = 1：线程退出未捕获的异常 （组= 0xa4b8f648）07-14 19：00：15.633 29316-29316 / com.protogeo.moves.demos.apps E / AndroidRuntime：FATAL 例外：主要 显示java.lang.NullPointerException 在android.widget.ArrayAdapter.getCount（ArrayAdapter.java:330） 在android.widget.ListView.onMeasure（ListView.java:1128） 在android.view.View.measure（View.java:15848） 在android.widget.RelativeLayout.measureChildHorizontal（RelativeLayout.java:728） 在android.widget.RelativeLayout.onMeasure（RelativeLayout.java:477） 在android.view.View.measure（View.java:15848） 在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5012） 在android.widget.FrameLayout.onMeasure（FrameLayout.java:310） 在android.view.View.measure（View.java:15848） 在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5012） 在com.android.internal.widget.ActionBarOverlayLayout.onMeasure（ActionBarOverlayLayout.java:302） 在android.view.View.measure（View.java:15848） 在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:5012） 在android.widget.FrameLayout.onMeasure（FrameLayout.java:310） 在com.android.internal.policy.impl.PhoneWindow $ DecorView.onMeasure（PhoneWindow.java:2189） 在android.view.View.measure（View.java:15848） 在android.view.ViewRootImpl.performMeasure（ViewRootImpl.java:1905） 在android.view.ViewRootImpl.measureHierarchy（ViewRootImpl.java:1104） 在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1284） 在android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:1004） 在android.view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:5481） 在android.view.Choreographer $ CallbackRecord.run（Choreographer.java:749） 在android.view.Choreographer.doCallbacks（Choreographer.java:562） 在android.view.Choreographer.doFrame（Choreographer.java:532） 在android.view.Choreographer $ FrameDisplayEventReceiver.run（Choreographer.java:735） 在android.os.Handler.handleCallback（Handler.java:730） 在android.os.Handler.dispatchMessage（Handler.java:92） 在android.os.Looper.loop（Looper.java:137） 在android.app.ActivityThread.main（ActivityThread.java:5103） at java.lang.reflect.Method.invokeNative（Native Method） 在java.lang.reflect.Method.invoke（Method.java:525） 在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:737） 在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:553） 在dalvik.system.NativeStart.main（本地方法）
我的MainActivity看起来像这样：
public class MainActivity extends FragmentActivity implements OnClickListener{
...
public void updateResponse() {
runOnUiThread(new Runnable() {
@Override
public void run() {
StorylineAdapter adapter = null;
try {
adapter = new StorylineAdapter(MainActivity.this, R.layout.item_storyline, summary);
// mEditTextResponse.setAdapter(adapter);
mEditTextResponse.setAdapter(adapter);
} catch (Exception e) {
e.printStackTrace();
}
我的ArrayAdapter课程如下：
public class StorylineAdapter extends ArrayAdapter<SummaryData>{
private Context context;
private Runnable runnable;
private ArrayList<StorylineData> storylineData;
public StorylineAdapter(Context context, int resource, ArrayList<SummaryData> objects) {
super(context, resource, objects);
this.context = context;
this.runnable = runnable;
this.summary = objects;
}
@Override
public View getView(int position, View convertView, ViewGroup parent){
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.item_storyline, parent, false);
/*LayoutInflater inflater =
(LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.item_storyline, parent, false);
*/
//Display in the TextView widget
SummaryData summary1 = summary.get(position);
TextView tv = (TextView) view.findViewById(R.id.textView1);
tv.setText(summary1.getActivity());
return view;
}
}
这是我的解析器类：
public class StorylineData extends ArrayList<StorylineData> {
...Getters/Setters...
/** ******************* Parser methods
/**
* Parse a {@link org.json.JSONObject} from storyline {@link org.json.JSONArray}, then return the corresponding {@link StorylineData} object.
*
* @param jsonObject : the storyline JSON object received from server
* @return corresponding {@link StorylineData}
*/
public static StorylineData parse(JSONObject jsonObject) throws JSONException {
if (jsonObject != null) {
StorylineData storylineData = new StorylineData();
storylineData.date = jsonObject.optString("date");
storylineData.caloriesIdle = jsonObject.optInt("caloriesIdle");
storylineData.lastUpdate = jsonObject.optString("lastUpdate");
storylineData.summary = new ArrayList<SummaryData>();
storylineData.segments = new ArrayList<SegmentData>();
/**Get the data associated with the array named summary **To get a specific JSONArray: Summary*/
JSONArray summariesJsonArray = jsonObject.optJSONArray("summary");
if (summariesJsonArray != null)
for (int i = 0; i < summariesJsonArray.length(); i++) {
/**each time through array will need to get a reference of current object*/
JSONObject summaryJsonObject = summariesJsonArray.optJSONObject(i);//declare instance of class object ob //array object called getJSONObject //passin indexvalu of (i)
if (summaryJsonObject != null) {
/**===============Translate data from json to Java=================*/
/**Create a new OBJECT OF ARRAY STORYLINE/SUMMARY*/
ArrayList<SummaryData> summary = new ArrayList<SummaryData>(); // initialisation must be outside the loop
storylineData.setSummary(summary);
/**Get summary from json into java*/
summariesJsonArray.getJSONObject(i).getString("distance");
/**Get date from json into java*/
String date = summaryJsonObject.optString("date");
storylineData.setDate(date);
/**Get group from json into java*/
String group = summaryJsonObject.optString("group");//Get name using key e.g. date
storylineData.setGroup(group);
/**Get distance from json into java*/
Integer distance = summaryJsonObject.optInt("distance");//Get name using key e.g. date
storylineData.setDistance(distance);
/**Get duration from json into java*/
Integer duration = summaryJsonObject.optInt("duration");
storylineData.setDuration(duration);
/**Get activity from json into java*/
String activity = summaryJsonObject.optString("activity");//Get name using key e.g. date
storylineData.setActivity(activity);
storylineData.summary.add(SummaryData.parse(summaryJsonObject));
Log.d("StorylineDataCls \t sJo", summaryJsonObject.toString() + "Log\n");
System.out.println("print distance" + summariesJsonArray.getJSONObject(i).getString("distance"));
System.out.println("print summary" + summaryJsonObject);
}
}
JSONArray segmentsJsonArray = jsonObject.optJSONArray("segments");
if (segmentsJsonArray != null) {
for (int i = 0; i < segmentsJsonArray.length(); i++) {
JSONObject segment = segmentsJsonArray.optJSONObject(i);
if (segment != null) {
ArrayList<SegmentData> segments = new ArrayList<SegmentData>(); // initialisation must be outside the loop
storylineData.setSegments(segments);
String type = segment.optString("type");
storylineData.setType(type);
String startTime = segment.optString("startTime");
storylineData.setStartTime(startTime);
String endTime = segment.optString("endTime");
storylineData.setEndTime(endTime);
/**Get steps from json into java*/
Integer activities = segment.optInt("place");
storylineData.setSteps(activities);
Integer calories = segment.optInt("calories");
storylineData.setCalories(calories);
String lastUpdate = segment.optString("lastUpdate");
storylineData.setLastUpdate(lastUpdate);
/**Get group from json into java*/
Integer caloriesIdle = segment.optInt("caloriesIdle");
storylineData.setCaloriesIdle(caloriesIdle);
storylineData.segments.add(SegmentData.parse(segment));
Log.d("StorylineDataCls \t sSo", segment.toString());
}
}
}
return storylineData;
}
return null;
}
}
答案 0 :(得分：1)
看起来像＆＃34;摘要＆＃34;一片空白。在创建和设置适配器之前检查null。
if (summary == null) {
// handle the error
Toast.makeText(this, "Error: no result", Toast.LENGTH_LONG).show();
} else {
StorylineAdapter adapter = new StorylineAdapter(MainActivity.this, R.layout.item_storyline, summary);
mEditTextResponse.setAdapter(adapter);
}
答案 1 :(得分：0)
您应该在适配器中添加getCount方法。这可能看起来像这样：
public class StorylineAdapter extends ArrayAdapter<SummaryData>{
//Keep your other methods as they stand
...
@Override
public int getCount()
{
if (summary!=null)
{
return summary.size();
}
else
{
Log.e("Adapter","Summary array is null");
return 0;
}
}