在RecyclerView中显示SQLite DB数组列表时总是崩溃
在RecyclerView中显示SQLite DB数组列表时总是崩溃
提问于 2019-05-21 01:39:54
我正在设置一个RecyclerView来查看数据库中数据的ArrayList (最初为空)。然而，它一直在Android虚拟设备上崩溃。我是Android Studio的新手，我正在做一个个人项目。我使用了不同的书籍和视频来创造我所拥有的东西。
我正在尝试按字母顺序列出具有共同类别的所有数据。但如果数据不存在，则显示id/emptyView textView。
我想我的错误可能是在我的适配器中，在ViewHolder中选择了错误的textViews，或者在onCreateViewHolder中选择了错误的膨胀布局，因为我有点困惑，他们应该指出这一点。或者我的db.query游标中的错误。
Logcat：
FATAL EXCEPTION: main
Process: com.HSC.calendarfit, PID: 10164
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.HSC.calendarfit/com.HSC.calendarfit.ExerciseList}: android.database.sqlite.SQLiteException: unrecognized token: ""Arms ORDER BY exerciseName ASC" (code 1 SQLITE_ERROR): , while compiling: SELECT exerciseName FROM exerciseList WHERE muscleGroup = "Arms ORDER BY exerciseName ASC
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: android.database.sqlite.SQLiteException: unrecognized token: ""Arms ORDER BY exerciseName ASC" (code 1 SQLITE_ERROR): , while compiling: SELECT exerciseName FROM exerciseList WHERE muscleGroup = "Arms ORDER BY exerciseName ASC
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:903)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:514)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:46)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1408)
at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1255)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1126)
at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1294)
at com.HSC.calendarfit.dbExerciseListHandler$override.getExercises(dbExerciseListHandler.java:65)
at com.HSC.calendarfit.dbExerciseListHandler$override.access$dispatch(Unknown Source:64)
at com.HSC.calendarfit.dbExerciseListHandler.getExercises(Unknown Source:15)
at com.HSC.calendarfit.ExerciseList.onCreate(ExerciseList.java:43)
at android.app.Activity.performCreate(Activity.java:7136)
at android.app.Activity.performCreate(Activity.java:7127)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)在activity中调用适配器和方法：
dbHandler = new dbExerciseListHandler(this, null, null, 1);
muscleCategory = "Arms";
List<dbExerciseList> list = dbHandler.getExercises(muscleCategory);
recyclerView = (RecyclerView) findViewById(R.id.rvExerciseList);
emptyView = (TextView) findViewById(R.id.emptyView);
if (list.isEmpty()){
recyclerView.setVisibility(View.GONE);
emptyView.setVisibility(View.VISIBLE);
}else{
recyclerView.setVisibility(View.VISIBLE);
emptyView.setVisibility(View.GONE);
}
recyclerView.setHasFixedSize(true);
mAdapter = new ExerciseListAdapter(list);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(mAdapter); 方法来获取数据并创建数组列表：
public List<dbExerciseList> getExercises(String muscleGroup){
List<dbExerciseList> list = new ArrayList<>();
SQLiteDatabase db = this.getWritableDatabase();
String[] columnsToUse = {COLUMN_EXERCISENAME};
Cursor cursor = db.query(TABLE_EXERCISE, columnsToUse, COLUMN_MUSCLEGROUP + " = \"" +
muscleGroup, null, null, null, COLUMN_EXERCISENAME + "ASC");
while (cursor.moveToNext()){
String exerciseName = cursor.getString(0);
dbExerciseList name = new dbExerciseList(exerciseName);
list.add(name);
}
return list;
}dbExerciseList有我的getter和setter方法。
RecyclerView适配器：
public class ExerciseListAdapter extends RecyclerView.Adapter<ExerciseListAdapter.ExerciseListViewHolder>{
private List<dbExerciseList> mDataset;
public class ExerciseListViewHolder extends RecyclerView.ViewHolder {
public TextView tvExerciseName;
public ExerciseListViewHolder(@NonNull View itemView) {
super(itemView);
tvExerciseName = itemView.findViewById(R.id.tvExerciseName);
}
}
public ExerciseListAdapter(List<dbExerciseList> mDataset) {
this.mDataset = mDataset;
}
@Override
public ExerciseListViewHolder onCreateViewHolder( ViewGroup viewGroup, int i) {
TextView v = (TextView) LayoutInflater.from(viewGroup.getContext()).
inflate(R.layout.activity_exercise_list, viewGroup, false);
return new ExerciseListViewHolder(v);
}
@Override
public void onBindViewHolder(ExerciseListViewHolder exerciseListViewHolder, int position) {
dbExerciseList item = mDataset.get(position);
exerciseListViewHolder.tvExerciseName.setText(item.get_exerciseName());
}
@Override
public int getItemCount() {
return mDataset.size();
}
}谢谢。
回答 1
Stack Overflow用户
回答已采纳
发布于 2019-05-21 03:03:36
在getExercises()内部，下面这行代码：
Cursor cursor = db.query(TABLE_EXERCISE, columnsToUse, COLUMN_MUSCLEGROUP + " = \"" +
muscleGroup, null, null, null, COLUMN_EXERCISENAME + "ASC");这是什么：\"？
这就是这个字符串：
SELECT exerciseName FROM exerciseList WHERE muscleGroup = "Arms ORDER BY exerciseName ASC这在语法上是错误的，因为有双引号。
更改为：
Cursor cursor = db.query(TABLE_EXERCISE, columnsToUse, COLUMN_MUSCLEGROUP
+ " = '" + muscleGroup + "'", null, null, null, COLUMN_EXERCISENAME + "ASC");(这是您想要做的吗？)
但是，由于这种方式容易发生sql注入，因此最好使用这种方式将参数传递给sql语句：
String strQuery = "SELECT " + COLUMN_EXERCISENAME + " FROM " + TABLE_EXERCISE +
" WHERE " + COLUMN_MUSCLEGROUP + " = ? ORDER BY " + COLUMN_EXERCISENAME + " ASC";
Cursor cursor = db.rawQuery(strQuery, new String[] {muscleGroup});这样你就不必担心你传递的参数的类型了。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/56225759
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