Android SQLite数据库返回Null

我正在开发一个应用程序，该应用程序可以通过数据库查询来膨胀和自动完成文本视图。我遇到的问题是，当我调用该方法来膨胀TextView时，我无法访问数据库

TextChanged Listener（取自CustomAutocompleteTextChangedListener.java）：

堆栈跟踪：

02-01 10:50:08.201  14164-14164/com.vindsiden.windwidget E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.vindsiden.windwidget, PID: 14164
java.lang.NullPointerException
        at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:256)
        at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224)
        at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
        at com.vindsiden.windwidget.config.DatabaseHandler.read(DatabaseHandler.java:143)
        at com.vindsiden.windwidget.Vindsiden.getItemsFromDb(Vindsiden.java:483)
        at com.vindsiden.windwidget.config.CustomAutocompleteTextChangedListener.onTextChanged(CustomAutocompleteTextChangedListener.java:38)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.handleTextChanged(TextView.java:7467)
        at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:9183)
        at android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:962)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:496)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:435)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:30)
        at android.view.inputmethod.BaseInputConnection.replaceText(BaseInputConnection.java:675)
        at android.view.inputmethod.BaseInputConnection.setComposingText(BaseInputConnection.java:437)
        at com.android.internal.view.IInputConnectionWrapper.executeMessage(IInputConnectionWrapper.java:333)
        at com.android.internal.view.IInputConnectionWrapper$MyHandler.handleMessage(IInputConnectionWrapper.java:77)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5017)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
        at dalvik.system.NativeStart.main(Native Method)

完整代码可通过以下方式获得：

---

您传递给

SQLiteOpenHelper

父构造函数的

上下文是
null
第38行是什么
CustomAutocompleteTextChangedListener.java
？它来自我使用的示例。它建议创建一个CustomAutocompleteTextChangedListener来调用数据库并正确膨胀自动完成列表。（这是第一段代码）是否有更聪明的方法来实现这一点？从github链接上看，您是在暗示活动类错误。这个
vindsiden
是空的，我想我应该怎么做才能正确呢？读一下拉格哈夫·苏德的答案，你会明白，这听起来可能很傻。但是我该怎么解决这个问题呢？杰普：代码还没有真正清理干净。这就是你看到的stacktrace的原因。问题中的代码没有显示如何创建帮助器。
 public List<Sted> read(String searchTerm) {
    List<Sted> recordList = new ArrayList<Sted>();
    //Select query
    String sql = "";
    sql += "SELECT * FROM" + TABLE_PLACES;
    sql += " WHERE " + COLUMN_NAME + " LIKE '%" + searchTerm + "%'";
    sql += " ORDER BY " + COLUMN_ID + " DESC";
    sql += " LIMIT 0,5";


    //The line under is what is returning null
    SQLiteDatabase database = this.getWritableDatabase();


    //execute the query
    Cursor cursor = database.rawQuery(sql, null);

    //Looping rows and adding to the list

    if (cursor.moveToFirst()) {

        do {
            String objectName = cursor.getString(cursor.getColumnIndex(COLUMN_NAME));
            Sted sted = new Sted();

            recordList.add(sted);
        } while (cursor.moveToNext());
    }
    cursor.close();
    database.close();
    return recordList;

}

   public Sted findPlace(String placeName) {

    String query = "Select * FROM " + TABLE_PLACES + " WHERE " + COLUMN_NAME + " =  \"" + placeName + "\"";
    SQLiteDatabase database = this.getWritableDatabase();
    Cursor cursor = database.rawQuery(query, null);
    Sted sted = new Sted();

    if (cursor.moveToFirst()) {
        cursor.moveToFirst();
        sted.set_id(Integer.parseInt(cursor.getString(0)));
        sted.set_stedsNavn(cursor.getString(1));
        sted.set_url(cursor.getString(2));
        cursor.close();

    } else {
        sted = null;

    }
    database.close();
    return sted;


}

02-01 10:50:08.201  14164-14164/com.vindsiden.windwidget E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.vindsiden.windwidget, PID: 14164
java.lang.NullPointerException
        at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:256)
        at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224)
        at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
        at com.vindsiden.windwidget.config.DatabaseHandler.read(DatabaseHandler.java:143)
        at com.vindsiden.windwidget.Vindsiden.getItemsFromDb(Vindsiden.java:483)
        at com.vindsiden.windwidget.config.CustomAutocompleteTextChangedListener.onTextChanged(CustomAutocompleteTextChangedListener.java:38)
        at android.widget.TextView.sendOnTextChanged(TextView.java:7408)
        at android.widget.TextView.handleTextChanged(TextView.java:7467)
        at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:9183)
        at android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:962)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:496)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:435)
        at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:30)
        at android.view.inputmethod.BaseInputConnection.replaceText(BaseInputConnection.java:675)
        at android.view.inputmethod.BaseInputConnection.setComposingText(BaseInputConnection.java:437)
        at com.android.internal.view.IInputConnectionWrapper.executeMessage(IInputConnectionWrapper.java:333)
        at com.android.internal.view.IInputConnectionWrapper$MyHandler.handleMessage(IInputConnectionWrapper.java:77)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5017)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
        at dalvik.system.NativeStart.main(Native Method)