爲什麼我得到ClassCastException

我似乎得到一個ClassCastException錯誤。我相信它與我嘗試創建獨特的字符串，即「item」+ getItemId（pos），但我不確定爲什麼。爲什麼我得到ClassCastException

我的代碼是：

@Override 
    public View getView(int position, View itemLayout, ViewGroup parent) { 
      final int pos = position; 
      final String ITEM = "item"; 
      // TODO - Get the current ToDoItem 
      final ToDoItem toDoItem = (ToDoItem) getItem(position); 
      Log.i(TAG,"toDoItem: " + toDoItem + " getItem(position) :" + position + "View convertView: " + itemLayout); 

      // TODO - Inflate the View for this ToDoItem 
      // from todo_item.xml 
      if (itemLayout == null) { 
      LayoutInflater inflater = (LayoutInflater) mContext.getSystemService 
        (Context.LAYOUT_INFLATER_SERVICE); 

      itemLayout = (RelativeLayout) inflater.inflate(R.layout.todo_item, null); 
      //convertView = itemLayout; 
      Log.i(TAG,"itemLayout: " + itemLayout); 
     } 


     // TODO - Fill in specific ToDoItem data 
     // Remember that the data that goes in this View 
     // corresponds to the user interface elements defined 
     // in the layout file 
     final ToDoItem toDo = (ToDoItem) getItem(position); 

     // TODO - Display Title in TextView 
     final TextView titleView = (TextView) itemLayout.findViewById(R.id.titleView); 
     titleView.setText(toDo.getTitle()); 

     // TODO - Set up Status CheckBox 
     final CheckBox statusView = (CheckBox) itemLayout.findViewById(R.id.statusCheckBox); 

     Log.i(TAG," toDo.getStatus() :" + toDo.getStatus()); 

     if (getLongFromPreferences("item"+getItemId(pos)) != -1) { 
      boolean isChecked = getBooleanFromPreferences("item"+getItemId(pos)); 
      statusView.setChecked(isChecked); 
     } else 
      if (toDo.getStatus() == toDo.DONE) { 
      statusView.setChecked(true); 
     } 


     statusView.setOnCheckedChangeListener(new OnCheckedChangeListener() { 
     @Override 
     public void onCheckedChanged(CompoundButton buttonView, 
       boolean isChecked) { 

      Log.i(TAG, "Entered onCheckedChanged()"); 
      putLongInPreferences(getItemId(pos),"item"+getItemId(pos)); 
      putBooleanInPreferences(isChecked,"item"+getItemId(pos)); 


      // TODO - set up an OnCheckedChangeListener, which 
      // is called when the user toggles the status checkbox 
      //int getPos = (Integer) buttonView.getTag(); 
     } 
    }); 

      // TODO - Display Priority in a TextView 

      final TextView priorityView = (TextView) itemLayout.findViewById(R.id.priorityView); 
      priorityView.setText(toDo.getPriority().toString()); 

      // TODO - Display Time and Date. 
      // Hint - use ToDoItem.FORMAT.format(toDoItem.getDate()) to get date and 
      // time String 

      final TextView dateView = (TextView) itemLayout.findViewById(R.id.dateView); 
      dateView.setText(ToDoItem.FORMAT.format(toDoItem.getDate())); 

      // Return the View you just created 
      return itemLayout; 
} 


public void putBooleanInPreferences(boolean isChecked,String key){ 
    SharedPreferences sharedPreferences = mContext.getSharedPreferences(TAG,Context.MODE_PRIVATE); 
    SharedPreferences.Editor editor = sharedPreferences.edit(); 
    editor.putBoolean(key, isChecked); 
    editor.commit();   
} 
public boolean getBooleanFromPreferences(String key){ 
    SharedPreferences sharedPreferences = mContext.getSharedPreferences(TAG,Context.MODE_PRIVATE); 
    Boolean isChecked = sharedPreferences.getBoolean(key, false); 
    return isChecked;  
} 
public void putStringInPreferences(String isString,String key){ 
    SharedPreferences sharedPreferences = mContext.getSharedPreferences(TAG,Context.MODE_PRIVATE); 
    SharedPreferences.Editor editor = sharedPreferences.edit(); 
    editor.putString(key, isString); 
    editor.commit();   
} 
public String getStringFromPreferences(String key){ 
    SharedPreferences sharedPreferences = mContext.getSharedPreferences(TAG,Context.MODE_PRIVATE); 
    String isString = sharedPreferences.getString(key, "aString"); 
    return isString;  
} 
public void putLongInPreferences(long isString,String key){ 
    SharedPreferences sharedPreferences = mContext.getSharedPreferences(TAG,Context.MODE_PRIVATE); 
    SharedPreferences.Editor editor = sharedPreferences.edit(); 
    editor.putLong(key, isString); 
    editor.commit();   
} 
public long getLongFromPreferences(String key){ 
    SharedPreferences sharedPreferences = mContext.getSharedPreferences(TAG,Context.MODE_PRIVATE); 
    long isString = sharedPreferences.getLong(key, -1); 
    return isString;  
}

的的TodoItem是如下：

public class ToDoItem { 

public static final String ITEM_SEP = System.getProperty("line.separator"); 

public enum Priority { 
    LOW, MED, HIGH 
}; 

public enum Status { 
    NOTDONE, DONE 
}; 

public final static String TITLE = "title"; 
public final static String PRIORITY = "priority"; 
public final static String STATUS = "status"; 
public final static String DATE = "date"; 
public final static String FILENAME = "filename"; 

public final static SimpleDateFormat FORMAT = new SimpleDateFormat(
     "yyyy-MM-dd HH:mm:ss", Locale.US); 

private String mTitle = new String(); 
private Priority mPriority = Priority.LOW; 
private Status mStatus = Status.NOTDONE; 
private Date mDate = new Date(); 
public Status DONE = Status.DONE; 

ToDoItem(String title, Priority priority, Status status, Date date) { 
    this.mTitle = title; 
    this.mPriority = priority; 
    this.mStatus = status; 
    this.mDate = date; 
} 

// Create a new ToDoItem from data packaged in an Intent 

ToDoItem(Intent intent) { 

    mTitle = intent.getStringExtra(ToDoItem.TITLE); 
    mPriority = Priority.valueOf(intent.getStringExtra(ToDoItem.PRIORITY)); 
    mStatus = Status.valueOf(intent.getStringExtra(ToDoItem.STATUS)); 

    try { 
     mDate = ToDoItem.FORMAT.parse(intent.getStringExtra(ToDoItem.DATE)); 
    } catch (ParseException e) { 
     mDate = new Date(); 
    } 
} 

public String getTitle() { 
    return mTitle; 
} 

public void setTitle(String title) { 
    mTitle = title; 
} 

public Priority getPriority() { 
    return mPriority; 
} 

public void setPriority(Priority priority) { 
    mPriority = priority; 
} 

public Status getStatus() { 
    return mStatus; 
} 

public void setStatus(Status status) { 
    mStatus = status; 
} 

public Date getDate() { 
    return mDate; 
} 

public void setDate(Date date) { 
    mDate = date; 
} 

// Take a set of String data values and 
// package them for transport in an Intent 

public static void packageIntent(Intent intent, String title, 
     Priority priority, Status status, String date) { 

    intent.putExtra(ToDoItem.TITLE, title); 
    intent.putExtra(ToDoItem.PRIORITY, priority.toString()); 
    intent.putExtra(ToDoItem.STATUS, status.toString()); 
    intent.putExtra(ToDoItem.DATE, date); 

} 

public String toString() { 
    return mTitle + ITEM_SEP + mPriority + ITEM_SEP + mStatus + ITEM_SEP 
      + FORMAT.format(mDate); 
} 

public String toLog() { 
    return "Title:" + mTitle + ITEM_SEP + "Priority:" + mPriority 
      + ITEM_SEP + "Status:" + mStatus + ITEM_SEP + "Date:" 
      + FORMAT.format(mDate); 
}

}

我logcat的是：

10-27 17:20:46.944: E/AndroidRuntime(2734): FATAL EXCEPTION: main 
10-27 17:20:46.944: E/AndroidRuntime(2734): java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.Long 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.app.SharedPreferencesImpl.getLong(SharedPreferencesImpl.java:247) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at course.labs.todomanager.ToDoListAdapter.getLongFromPreferences(ToDoListAdapter.java:202) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at course.labs.todomanager.ToDoListAdapter.getView(ToDoListAdapter.java:127) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.widget.HeaderViewListAdapter.getView(HeaderViewListAdapter.java:220) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.widget.AbsListView.obtainView(AbsListView.java:2177) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.widget.ListView.makeAndAddView(ListView.java:1840) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.widget.ListView.fillDown(ListView.java:675) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.widget.ListView.fillFromTop(ListView.java:736) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.widget.ListView.layoutChildren(ListView.java:1655) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.widget.AbsListView.onLayout(AbsListView.java:2012) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.View.layout(View.java:14289) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.ViewGroup.layout(ViewGroup.java:4562) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.widget.FrameLayout.onLayout(FrameLayout.java:448) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.View.layout(View.java:14289) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.ViewGroup.layout(ViewGroup.java:4562) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at com.android.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:349) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.View.layout(View.java:14289) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.ViewGroup.layout(ViewGroup.java:4562) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.widget.FrameLayout.onLayout(FrameLayout.java:448) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.View.layout(View.java:14289) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.ViewGroup.layout(ViewGroup.java:4562) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1976) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1730) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5481) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.Choreographer.doCallbacks(Choreographer.java:562) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.Choreographer.doFrame(Choreographer.java:532) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.os.Handler.handleCallback(Handler.java:730) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.os.Handler.dispatchMessage(Handler.java:92) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.os.Looper.loop(Looper.java:137) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at android.app.ActivityThread.main(ActivityThread.java:5103) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at java.lang.reflect.Method.invoke(Method.java:525) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
10-27 17:20:46.944: E/AndroidRuntime(2734):  at dalvik.system.NativeStart.main(Native Method)

來源

2014-10-27 chestchindian

已存儲一個布爾值，所以你應該讀它作爲一個布爾值，不長。 – 2014-10-27 17:24:00

其中是你的getItemId（）？ – 2014-10-27 17:24:27

仔細看看getLongFromPreferences正在做什麼。問題可能在那裏。使用你的調試工具。 – FelixMarcus 2014-10-27 17:26:06

我suggestio n是爲Long和"itemBoolean"+getItemId(pos)在使用"itemLong"+getItemId(pos)爲布爾

問題可能是由於您的'key'字符串。您正在使用

"item"+getItemId(pos)

兩個布爾和長（不知何故getItemId(pos)變得同爲Boolean和Long）

來源

2014-10-27 17:37:47 fatboy

感謝fatboy，這似乎已經做到了。這還包括FelixMarcus和Chris Stratton，他給了我一個想法，就是看，歡呼，配對:) – chestchindian 2014-10-28 00:33:42

爲什麼我得到ClassCastException

回答

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