问题
Hi everyone I’ve been having some difficulty, hope one of you can help. I’m trying to create a little program to store my timetable for college. I’ve been having some trouble with the SQlite database though, it’s got me stumped.
When I first run the program it force closes
I get this error in logcat
Caused by: android.database CursorIndexOutOfBoundsException: Index 0 requested. With a size of 0
When I go to open the application again the table is created and the app works fine.
I have no idea why the table is not being created the first time round.
Here’s the code.
public class Monday extends ListActivity {
int pos = 0, timeInt, count;
String[] times = {"0900-1030","1040-1220","Lunch 1220-1325","1325-1455", "1500-1630"};
String[][] content;
String dayString = "Monday", timeString;
EditText EditTextLesson, EditTextLocation, EditTextTutor, EditTextNotes;
Button btnSave, btnCancel , btnDelete;
Dialog edit;
Intent zoom , mapweb;
Cursor all, getRow;
MonDBAdapter mon;
DBAdapter db;
ListView lv;
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.timetablelistview);
content= new String [10][10];
edit = new Dialog(Monday.this);
lv = (ListView) findViewById(android.R.id.list);
lv.addFooterView(buildFooter());
zoom =new Intent(this,Zoom.class);
mapweb =new Intent(this,MapWebView.class);
db = new DBAdapter(this);
db.open();
mon = new MonDBAdapter(this);
mon.open();
all = mon.getAllEntries();
count = all.getCount();
if(count < 4){
for(int i = 0; i < 5; i++){
mon.createEntry("", "", "", "");
}
}
addSections();
}
public void onListItemClick(ListView parent, View v, int position, long id){
switch(position){
case 1:
timeInt= 1;
timeString=("0900-1030");
break;
case 3:
timeInt= 2;
timeString=("1040-1220");
break;
case 5:
timeInt= 3;
timeString=("1220-1325");
break;
case 7:
timeInt= 4;
timeString=("1325-1455");
break;
case 9:
timeInt= 5;
timeString=("1500-1630");
break;
}
editDialog();
}
SectionedAdapter adapter=new SectionedAdapter() {
protected View getHeaderView(String caption, int index,
View convertView,
ViewGroup parent) {
TextView result=(TextView)convertView;
if (convertView==null) {
result=(TextView)getLayoutInflater().inflate(R.layout.header,
null);
}
result.setText(caption);
return(result);
}
};
public void addSections(){
all.moveToFirst();
for(int i = 0; i < 5; i++){
getSectionContent(
times[i],
all.getString(1),
all.getString(2),
all.getString(3),
all.getString(4));
all.moveToNext();
}
}
public void getSectionContent(String time,String lesson,String location,String tutor,String notes){
//adapter to add content to each section
String[] from = new String[] {"lesson", "location", "tutor", "notes"};
int[] to = new int[] {R.id.textViewLesson, R.id.textViewLocation, R.id.textViewTutor, R.id.textViewNotes };
// prepare the list of all records
List<HashMap<String, String>> fillMaps = new ArrayList<HashMap<String, String>>();
HashMap<String, String> map = new HashMap<String, String>();
map.put("lesson", lesson );
map.put("location", location );
map.put("tutor", tutor );
map.put("notes", notes );
fillMaps.add(map);
SimpleAdapter adapter1 = new SimpleAdapter(this, fillMaps, R.layout.list_view_item, from, to);
adapter.addSection(time,adapter1);
lv.setAdapter(adapter);
}
public void editDialog(){
getRow = mon.getEntry(timeInt);
edit.setTitle("Edit "+ dayString + " " + timeString);
edit.setContentView(R.layout.edit);
edit.setCancelable(true);
btnSave = (Button)edit.findViewById(R.id.btnSave);
btnCancel = (Button)edit.findViewById(R.id.btnCancel);
btnDelete = (Button)edit.findViewById(R.id.btnDelete);
EditTextLesson=(EditText)edit.findViewById(R.id.editTextLesson);
EditTextLocation=(EditText)edit.findViewById(R.id.editTextLocation);
EditTextTutor=(EditText)edit.findViewById(R.id.editTextTutor);
EditTextNotes=(EditText)edit.findViewById(R.id.editTextNotes);
EditTextLesson.setText(getRow.getString(1));
EditTextLocation.setText(getRow.getString(2));
EditTextTutor.setText(getRow.getString(3));
EditTextNotes.setText(getRow.getString(4));
btnCancel.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
edit.cancel();
}
});
btnSave.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
//starts at 1 as 0 contain the section time
mon.updateEntry(timeInt,EditTextLesson.getText().toString(),EditTextLocation.getText().toString(), EditTextTutor.getText().toString(),EditTextNotes.getText().toString());
all.requery();
adapter.sections.clear();
addSections();
edit.cancel();
}
});
btnDelete.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
EditTextLesson.setText("");
EditTextLocation.setText("");
EditTextTutor.setText("");
EditTextNotes.setText("");
}
});
edit.show();
}
private View buildFooter() {
Button btn=new Button(this);
btn.setText("Campus map");
btn.setTextSize(18);
btn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if(VERSION.SDK.equals("4")||VERSION.SDK.equals("3")||VERSION.SDK.equals("2")||VERSION.SDK.equals("1")){
startActivity(zoom);
}else{
startActivity(mapweb);
}
}
});
return(btn);
}
}
public class DBAdapter {
public static final String DATABASE_NAME = "timetable";
public static final int DATABASE_VERSION = 1;
private static final String MONDAY =
"create table monday (_id integer primary key autoincrement, "
+ MonDBAdapter.LESSON+ " TEXT,"
+ MonDBAdapter.LOCATION+ " TEXT,"
+ MonDBAdapter.TUTOR+ " TEXT,"
+ MonDBAdapter.NOTES+ " TEXT" + ");";
private static final String TUESDAY =
"create table tuesday (_id integer primary key autoincrement, "
+ MonDBAdapter.LESSON+ " TEXT,"
+ MonDBAdapter.LOCATION+ " TEXT,"
+ MonDBAdapter.TUTOR+ " TEXT,"
+ MonDBAdapter.NOTES+ " TEXT" + ");";
private static final String WEDNESDAY =
"create table wednesday (_id integer primary key autoincrement, "
+ MonDBAdapter.LESSON+ " TEXT,"
+ MonDBAdapter.LOCATION+ " TEXT,"
+ MonDBAdapter.TUTOR+ " TEXT,"
+ MonDBAdapter.NOTES+ " TEXT" + ");";
private static final String THURSDAY =
"create table thursday (_id integer primary key autoincrement, "
+ MonDBAdapter.LESSON+ " TEXT,"
+ MonDBAdapter.LOCATION+ " TEXT,"
+ MonDBAdapter.TUTOR+ " TEXT,"
+ MonDBAdapter.NOTES+ " TEXT" + ");";
private static final String FRIDAY =
"create table friday (_id integer primary key autoincrement, "
+ MonDBAdapter.LESSON+ " TEXT,"
+ MonDBAdapter.LOCATION+ " TEXT,"
+ MonDBAdapter.TUTOR+ " TEXT,"
+ MonDBAdapter.NOTES+ " TEXT" + ");";
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
this.DBHelper = new DatabaseHelper(this.context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(MONDAY);
db.execSQL(TUESDAY);
db.execSQL(WEDNESDAY);
db.execSQL(THURSDAY);
db.execSQL(FRIDAY);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion)
{
}
}
public DBAdapter open() throws SQLException
{
this.db = this.DBHelper.getWritableDatabase();
return this;
}
public void close()
{
this.DBHelper.close();
}
}
public class MonDBAdapter {
public static final String ROW_ID = "_id";
public static final String LESSON = "name";
public static final String LOCATION = "model";
public static final String TUTOR = "year";
public static final String NOTES = "notes";
private static final String MONDAY= "monday";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
private final Context mCtx;
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DBAdapter.DATABASE_NAME, null, DBAdapter.DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
public MonDBAdapter(Context ctx) {
this.mCtx = ctx;
}
public MonDBAdapter open() throws SQLException {
this.mDbHelper = new DatabaseHelper(this.mCtx);
this.mDb = this.mDbHelper.getWritableDatabase();
return this;
}
public void close() {
this.mDbHelper.close();
}
public long createEntry(String lesson, String location, String tutor , String notes){
ContentValues initialValues = new ContentValues();
initialValues.put(LESSON, lesson);
initialValues.put(LOCATION, location);
initialValues.put(TUTOR, tutor);
initialValues.put(NOTES, notes);
return this.mDb.insert(MONDAY, null, initialValues);
}
public boolean deleteEntry(long rowId) {
return this.mDb.delete(MONDAY, ROW_ID + "=" + rowId, null) > 0; //$NON-NLS-1$
}
public Cursor getAllEntries() {
return this.mDb.query(MONDAY, new String[] { ROW_ID,
LESSON, LOCATION, TUTOR, NOTES }, null, null, null, null, null);
}
public Cursor getEntry(long rowId) throws SQLException {
Cursor mCursor =
this.mDb.query(true, MONDAY, new String[] { ROW_ID, LESSON,
LOCATION, TUTOR, NOTES}, ROW_ID + "=" + rowId, null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
public boolean updateEntry(long rowId, String lesson, String location,
String tutor, String notes){
ContentValues args = new ContentValues();
args.put(LESSON, lesson);
args.put(LOCATION, location);
args.put(TUTOR, tutor);
args.put(NOTES, notes);
return this.mDb.update(MONDAY, args, ROW_ID + "=" + rowId, null) >0;
}
Here's what I getting in logcat:
ERROR/AndroidRuntime(2464): FATAL EXCEPTION: main
ERROR/AndroidRuntime(2464): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.scotty65/com.scotty65.TabBarExample}: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.scotty65/com.scotty65.Monday}: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0
ERROR/AndroidRuntime(2464): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1768)
ERROR/AndroidRuntime(2464): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784)
ERROR/AndroidRuntime(2464): at android.app.ActivityThread.access$1500(ActivityThread.java:123)
ERROR/AndroidRuntime(2464): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939)
ERROR/AndroidRuntime(2464): at android.os.Handler.dispatchMessage(Handler.java:99)
ERROR/AndroidRuntime(2464): at android.os.Looper.loop(Looper.java:123)
ERROR/AndroidRuntime(2464): at android.app.ActivityThread.main(ActivityThread.java:3835)
ERROR/AndroidRuntime(2464): at java.lang.reflect.Method.invokeNative(Native Method)
ERROR/AndroidRuntime(2464): at java.lang.reflect.Method.invoke(Method.java:507)
ERROR/AndroidRuntime(2464): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
ERROR/AndroidRuntime(2464): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
/AndroidRuntime(2464): at dalvik.system.NativeStart.main(Native Method)
ERROR/AndroidRuntime(2464): Caused by: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.scotty65/com.scotty65.Monday}: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0
ERROR/AndroidRuntime(2464): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1768)
ERROR/AndroidRuntime(2464): at android.app.ActivityThread.startActivityNow(ActivityThread.java:1598)
ERROR/AndroidRuntime(2464): at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127)
ERROR/AndroidRuntime(2464): at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339)
回答1:
If you got through the documentation of getReadableDatabase, it says
Like getWritableDatabase(), this method may take a long time to return, so you should not call it from the application main thread, including from ContentProvider.onCreate()
And what I see in your program, first you are calling this in constructor of DBAdapter
this.DBHelper = new DatabaseHelper(this.context);
this.DBHelper.getWritableDatabase();
this.DBHelper.getReadableDatabase();
and then in onCreate you are calling db.open(); where you are again calling this.DBHelper.getWritableDatabase();
So, it might be possible yours database is not properly loaded. And try to do all this operation in background thread ex AsyncTask.
Hope this help!!!
回答2:
I don't see where you ever actually call the "close()" function to close the database when you are finished with it. Maybe try to close it after you are done adding your sections. I see you have provided methods for closing it but it doesn't look like you ever actually used them.
From the docs:
Once opened successfully, the database is cached, so you can call this method every time you need to write to the database. (Make sure to call close() when you no longer need the database.) Errors such as bad permissions or a full disk may cause this method to fail, but future attempts may succeed if the problem is fixed. Database upgrade may take a long time, you should not call this method from the application main thread, including from ContentProvider.onCreate().
来源：https://stackoverflow.com/questions/7122337/cursorindexoutofboundsexception-when-accessing-sqlite-database