我构建了一个android小部件，并在WidgetService类中扩展了BroadcastReceiver。
一个奇怪的事情发生了，当我尝试从ArrayList获取一个整数时，它会抛出一个异常
public class WidgetService extends BroadcastReceiver {
int currentIndex = -1;
ArrayList<Integer> indexHitTimes = null;
ArrayList<Integer> staredIndex = null;
HashMap<Integer, Integer> staredIndexHitTimes = null;
...
public void onReceive(Context context, Intent intent) {
...
updateCurrentIndex();
...
}
private void updateCurrentIndex(){
...
Random r = new Random();
int size = staredIndex.size();
int randomIndex = r.nextInt(size);
currentIndex = staredIndex.get(randomIndex); ->problem here
currentIndexHitTimes = staredIndexHitTimes.get(currentIndex);
minHitTimes = Collections.min(staredIndexHitTimes.values());
...
}
}
我检查它是否是由NullPointer引起的，但没有任何线索。
是我的jdk（版本1.8.0_74）还是android studio的问题？（版本1.51） Android SDK版本：6.0（但我尝试过4.4，仍然相同）
我尝试启动一个新项目并复制到它，但仍无效。
怎么可能？ 由于“staredIndex”是一个带有Integer参数的ArrayList，randomIndex是一个int，因此currentIndex是和int。
“Double”来自哪里？
如何解决？
错误消息
java.lang.RuntimeException: Unable to start receiver
heart.david.jp50_reviewer.WidgetService: java.lang.ClassCastException:
java.lang.Double cannot be cast to java.lang.Integer
at android.app.ActivityThread.handleReceiver(ActivityThread.java:2602)
at android.app.ActivityThread.access$1700(ActivityThread.java:147)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1358)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5253)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.ClassCastException: java.lang.Double cannot be cast to java.lang.Integer
at heart.david.jp50_reviewer.WidgetService.updateCurrentIndex(WidgetService.java:136)
at heart.david.jp50_reviewer.WidgetService.onReceive(WidgetService.java:51)
at android.app.ActivityThread.handleReceiver(ActivityThread.java:2595)
at android.app.ActivityThread.access$1700(ActivityThread.java:147)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1358)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5253)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
谢谢大家。我发现的问题就在这里。下面的代码初始化了ArrayList。
...
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context.getApplicationContext());
String json = sharedPreferences.getString("staredIndex", null);
if(json == null){
staredIndex = new ArrayList<Integer>();
for(int i=0;i<hashMap_Characters.size();i++){
boolean stared = hashMap_Stared.get(i);
if(stared){
staredIndex.add(i);
}
}
SharedPreferences.Editor editor = sharedPreferences.edit();
Gson gson = new Gson();
String staredIndex_json = gson.toJson(staredIndex);
editor.putString("staredIndex", staredIndex_json);
editor.commit();
}else{
Gson gson = new Gson();
staredIndex = gson.fromJson(json, ArrayList.class); -> here! the staredIndex filled with Doubles!
}
...
然后我改为这个，问题就完全解决了。
...
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context.getApplicationContext());
String json = sharedPreferences.getString("indexHitTimes", null);
if(json == null){
indexHitTimes = new ArrayList<Integer>();
for(int i=0;i<hashMap_Characters.size();i++){
indexHitTimes.add(0);
}
SharedPreferences.Editor editor = sharedPreferences.edit();
Gson gson = new Gson();
Type type = new TypeToken<ArrayList<Integer>>(){}.getType();
String indexHitTimes_json = gson.toJson(indexHitTimes, type);
editor.putString("indexHitTimes", indexHitTimes_json);
editor.commit();
}else{
Gson gson = new Gson();
indexHitTimes = (ArrayList<Integer>)gson.fromJson(json, new TypeToken<ArrayList<Integer>>(){}.getType());
}
...