我正在尝试从预先制作的SQLite数据库中读取位置（纬度，经度）值和标题。我得到的问题是它似乎在地图上显示标记，但与数据库中的值无关 - 这几乎就像它们被错误地读取一样。
My MonumentsDatabase.java类（我处理数据库的地方）：
public class MonumentsDatabase extends SQLiteOpenHelper {
public static String DATABASE_NAME = "antiquityDatabase.db";
public final static String DATABASE_PATH = "/data/data/com.example.antiquity/databases/";
private static final int DATABASE_VERSION = 1;
int _id;
double _lat;
double _lng;
String _title;
String _date;
String _description;
String[] _idColumn = {"_id"};
String[] latColumn = {"latitude"};
String[] lngColumn = {"longitude"};
String[] titleColumn = {"title"};
String[] dateColumn = {"date"};
String[] descColumn = {"description"};
private SQLiteDatabase database;
private final Context myContext;
public MonumentsDatabase(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
this.myContext = context;
}
public void createDatabase() throws IOException {
boolean databaseExist = checkDatabase();
if(databaseExist) {
//Do nothing
} else {
this.getReadableDatabase();
try {
copyDatabase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkDatabase() {
SQLiteDatabase checkDatabase = null;
try {
String myPath = DATABASE_PATH + DATABASE_NAME;
checkDatabase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
//database doesnt exist yet
}
if(checkDatabase != null) {
checkDatabase.close();
}
return checkDatabase != null ? true : false;
}
private void copyDatabase() throws IOException {
InputStream myInput = myContext.getAssets().open(DATABASE_NAME);
String outputFilename = DATABASE_PATH + DATABASE_NAME;
OutputStream myOutput = new FileOutputStream(outputFilename);
byte[] buffer = new byte[1024];
int length;
while((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDatabase() throws SQLException {
String myPath = DATABASE_PATH + DATABASE_NAME;
database = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(database != null) {
database.close();
}
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public int getID() {
Cursor idQuery = database.query("monuments", _idColumn, null, null, null, null, null);
if (idQuery.moveToFirst()) {
do {
StringBuilder sb = new StringBuilder();
int columnsQty = idQuery.getColumnCount();
for (int idx=0; idx<columnsQty; ++idx) {
sb.append(idQuery.getString(idx));
if (idx < columnsQty - 1)
sb.append("; ");
}
Log.v("getID() - ID", String.format("Row: %d, Values: %s", idQuery.getPosition(), sb.toString()));
}
while (idQuery.moveToNext());
}
return _id;
}
public void setID(int id) {
_id = id;
}
public double getLat() {
Cursor latQuery = database.query("monuments", latColumn, null, null, null, null, null);
latQuery.moveToFirst();
if (latQuery.moveToFirst()) {
do {
StringBuilder sb = new StringBuilder();
int columnsQty = latQuery.getColumnCount();
for (int idx=0; idx<columnsQty; ++idx) {
sb.append(latQuery.getString(idx));
if (idx < columnsQty - 1)
sb.append("; ");
}
Log.v("getLat() - LATITUDE", String.format("Row: %d, Values: %s", latQuery.getPosition(), sb.toString()));
}
while (latQuery.moveToNext());
}
return _lat;
}
public void setLat(double lat) {
_lat = lat;
}
public double getLng() {
Cursor lngQuery = database.query("monuments", lngColumn, null, null, null, null, null);
if (lngQuery.moveToFirst()) {
do {
StringBuilder sb = new StringBuilder();
int columnsQty = lngQuery.getColumnCount();
for (int idx=0; idx<columnsQty; ++idx) {
sb.append(lngQuery.getString(idx));
if (idx < columnsQty - 1)
sb.append("; ");
}
Log.v("getLng() - LONGITUDE", String.format("Row: %d, Values: %s", lngQuery.getPosition(), sb.toString()));
}
while (lngQuery.moveToNext());
}
return _lng;
}
public void setLng(double lng) {
_lng = lng;
}
// Handle the monuments titles
public String getTitle() {
Cursor titleQuery = database.query("monuments", titleColumn, null, null, null, null, null);
if (titleQuery.moveToFirst()) {
do {
StringBuilder sb = new StringBuilder();
int columnsQty = titleQuery.getColumnCount();
for (int idx=0; idx<columnsQty; ++idx) {
sb.append(titleQuery.getString(idx));
if (idx < columnsQty - 1)
sb.append("; ");
}
Log.v("getTitle() - TITLE", String.format("Row: %d, Values: %s", titleQuery.getPosition(), sb.toString()));
}
while (titleQuery.moveToNext());
}
return _title;
}
public void setTitle(String title) {
_title = title;
}
public String getDate() {
Cursor dateQuery = database.query("monuments", dateColumn, null, null, null, null, null, null);
if (dateQuery.moveToFirst()) {
do {
StringBuilder sb = new StringBuilder();
int columnsQty = dateQuery.getColumnCount();
for (int idx=0; idx<columnsQty; ++idx) {
sb.append(dateQuery.getString(idx));
if (idx < columnsQty - 1)
sb.append("; ");
}
Log.v("getDate() - DATE", String.format("Row: %d, Values: %s", dateQuery.getPosition(), sb.toString()));
}
while (dateQuery.moveToNext());
}
return _date;
}
public void setDate(String date) {
_date = date;
}
public String getDescription() {
Cursor descriptionQuery = database.query("monuments", descColumn, null, null, null, null, null, null);
if (descriptionQuery.moveToFirst()) {
do {
StringBuilder sb = new StringBuilder();
int columnsQty = descriptionQuery.getColumnCount();
for (int idx=0; idx<columnsQty; ++idx) {
sb.append(descriptionQuery.getString(idx));
if (idx < columnsQty - 1)
sb.append("; ");
}
Log.v("getDescription() - DESCRIPTION", String.format("Row: %d, Values: %s", descriptionQuery.getPosition(), sb.toString()));
}
while (descriptionQuery.moveToNext());
}
return _description;
}
public void setDescription(String description) {
_description = description;
}
public void addMarker(MarkerObject m) {
m.getTitle();
}
public ArrayList<MonumentsDatabase> arrayDB() {
ArrayList<MonumentsDatabase> aD = new ArrayList<MonumentsDatabase>();
//aD.add(getTitle());
return aD;
}
}
我的MainActivity.java类：
public class MainActivity extends FragmentActivity {
private GoogleMap map;
Intent data;
MonumentsDatabase monDatabase;
ArrayList<MonumentsDatabase> mDatabase;
int _id;
double _lat;
double _lng;
double sLat;
double sLng;
String _title;
String titles;
double lats;
double lngs;
LatLng markerPosition;
int i;
private Marker bigBen;
private Marker mainMarker;
private Marker parliamentSQ;
private Marker parliament;
private Marker random;
static final LatLng PARLIAMENT = new LatLng(51.499776600000000000, -0.125173099999983600);
//static final LatLng MARKERS = new LatLng(getLatitude(), getLongitude());
static final LatLng PARLIAMENTSQ = new LatLng(51.5006, -0.1267);
static final LatLng RANDOM = new LatLng(51.5019, -0.1257);
LocationManager locationManager;
Context context = this;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
map=((SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map)).getMap();
map.setOnInfoWindowClickListener(new OnInfoWindowClickListener() {
@Override
public void onInfoWindowClick(Marker marker) {
Intent data = new Intent(MainActivity.this, DisplayData.class);
startActivity(data);
}
});
ArrayList<MonumentsDatabase> mDB = createDatabase();
for(i = 0; i < mDB.size(); i++) {
//Get position of what the DB is and get the latitude and longitude
sLat = mDB.get(i).getLat();
sLng = mDB.get(i).getLng();
markerPosition = new LatLng(sLat, sLng);
map.addMarker(new MarkerOptions()
.position(markerPosition)
.title(mDB.get(i).getTitle())
.snippet("Click for more info.")
.icon(BitmapDescriptorFactory.fromResource(R.drawable.custom_marker)));
}
locationManager = (LocationManager) getSystemService( Context.LOCATION_SERVICE );
if ( !locationManager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
disabledGPS();
}
map.setMyLocationEnabled(true);
}
private void disabledGPS() {
final AlertDialog.Builder gpsDisabled = new AlertDialog.Builder(this);
gpsDisabled.setMessage("This app requires GPS to be enabled. Do you wish to continue?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
AlertDialog mainAlert = gpsDisabled.create();
mainAlert.show();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public ArrayList<MonumentsDatabase> createDatabase() {
monDatabase = new MonumentsDatabase(this);
try {
monDatabase.createDatabase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
try {
monDatabase.openDatabase();
}catch(SQLException sqle){
throw sqle;
}
mDatabase = new ArrayList<MonumentsDatabase>();
monDatabase.setTitle(titles);
monDatabase.setLat(lats);
monDatabase.setLng(lngs);
titles = monDatabase.getTitle();
lats = monDatabase.getLat();
lngs = monDatabase.getLng();
mDatabase.add(monDatabase);
return mDatabase;
}
}
我想要发生的是在Google地图上阅读和显示为标记的标题，纬度和经度值，目前SQLite数据库中有20条记录。
非常感谢任何帮助！
修改
Log cat打印出数据：
02-24 12:55:11.691: V/getTitle() - TITLE(18411): Row: 0, Values: Big Ben
02-24 12:55:11.692: V/getTitle() - TITLE(18411): Row: 1, Values: Swansea Castle
02-24 12:55:11.693: V/getTitle() - TITLE(18411): Row: 2, Values: Cardiff Castle
02-24 12:55:11.694: V/getTitle() - TITLE(18411): Row: 3, Values: Mumbles Lighthouse
02-24 12:55:11.695: V/getTitle() - TITLE(18411): Row: 4, Values: Sketty Hall
02-24 12:55:11.695: V/getTitle() - TITLE(18411): Row: 5, Values: St Mary's Church, Swansea
02-24 12:55:11.696: V/getTitle() - TITLE(18411): Row: 6, Values: Loughor
02-24 12:55:11.696: V/getTitle() - TITLE(18411): Row: 7, Values: Oystermouth Castle
02-24 12:55:11.696: V/getTitle() - TITLE(18411): Row: 8, Values: Oxwich Castle
02-24 12:55:11.696: V/getTitle() - TITLE(18411): Row: 9, Values: Penlle'r Castell
02-24 12:55:11.696: V/getTitle() - TITLE(18411): Row: 10, Values: Pennard Castle
02-24 12:55:11.698: V/getTitle() - TITLE(18411): Row: 11, Values: The Palace Theatre
02-24 12:55:11.699: V/getTitle() - TITLE(18411): Row: 12, Values: Morris Castle
02-24 12:55:11.699: V/getTitle() - TITLE(18411): Row: 13, Values: Castle Cinema
02-24 12:55:11.699: V/getTitle() - TITLE(18411): Row: 14, Values: Port Eynon
02-24 12:55:11.700: V/getTitle() - TITLE(18411): Row: 15, Values: Penrice Castle
02-24 12:55:11.700: V/getTitle() - TITLE(18411): Row: 16, Values: Weobley Castle
02-24 12:55:11.700: V/getTitle() - TITLE(18411): Row: 17, Values: St Fagans Castle
02-24 12:55:11.700: V/getTitle() - TITLE(18411): Row: 18, Values: Gregynog Hall
02-24 12:55:11.700: V/getTitle() - TITLE(18411): Row: 19, Values: Margam Castle
02-24 12:55:11.702: V/getLat() - LATITUDE(18411): Row: 0, Values: 51.5008
02-24 12:55:11.703: V/getLat() - LATITUDE(18411): Row: 1, Values: 51.6203
02-24 12:55:11.703: V/getLat() - LATITUDE(18411): Row: 2, Values: 51.4824
02-24 12:55:11.703: V/getLat() - LATITUDE(18411): Row: 3, Values: 51.5671
02-24 12:55:11.703: V/getLat() - LATITUDE(18411): Row: 4, Values: 51.6131
02-24 12:55:11.704: V/getLat() - LATITUDE(18411): Row: 5, Values: 51.619
02-24 12:55:11.704: V/getLat() - LATITUDE(18411): Row: 6, Values: 51.6626
02-24 12:55:11.704: V/getLat() - LATITUDE(18411): Row: 7, Values: 51.5765
02-24 12:55:11.704: V/getLat() - LATITUDE(18411): Row: 8, Values: 51.5546
02-24 12:55:11.705: V/getLat() - LATITUDE(18411): Row: 9, Values: 51.7691
02-24 12:55:11.705: V/getLat() - LATITUDE(18411): Row: 10, Values: 51.5766
02-24 12:55:11.705: V/getLat() - LATITUDE(18411): Row: 11, Values: 51.3739
02-24 12:55:11.705: V/getLat() - LATITUDE(18411): Row: 12, Values: 51.391
02-24 12:55:11.705: V/getLat() - LATITUDE(18411): Row: 13, Values: 51.3715
02-24 12:55:11.706: V/getLat() - LATITUDE(18411): Row: 14, Values: 51.5453
02-24 12:55:11.706: V/getLat() - LATITUDE(18411): Row: 15, Values: 51.5752
02-24 12:55:11.706: V/getLat() - LATITUDE(18411): Row: 16, Values: 51.6128
02-24 12:55:11.706: V/getLat() - LATITUDE(18411): Row: 17, Values: 51.4859
02-24 12:55:11.707: V/getLat() - LATITUDE(18411): Row: 18, Values: 52.3403
02-24 12:55:11.707: V/getLat() - LATITUDE(18411): Row: 19, Values: 51.5628
02-24 12:58:56.017: V/getLng() - LONGITUDE(18567): Row: 0, Values: -0.1247
02-24 12:58:56.018: V/getLng() - LONGITUDE(18567): Row: 1, Values: 3.9412
02-24 12:58:56.018: V/getLng() - LONGITUDE(18567): Row: 2, Values: 3.1811
02-24 12:58:56.018: V/getLng() - LONGITUDE(18567): Row: 3, Values: 3.9723
02-24 12:58:56.018: V/getLng() - LONGITUDE(18567): Row: 4, Values: 3.9883
02-24 12:58:56.020: V/getLng() - LONGITUDE(18567): Row: 5, Values: 3.943
02-24 12:58:56.020: V/getLng() - LONGITUDE(18567): Row: 6, Values: 4.06461
02-24 12:58:56.020: V/getLng() - LONGITUDE(18567): Row: 7, Values: 4.00297
02-24 12:58:56.020: V/getLng() - LONGITUDE(18567): Row: 8, Values: 4.16791
02-24 12:58:56.021: V/getLng() - LONGITUDE(18567): Row: 9, Values: 3.9356
02-24 12:58:56.024: V/getLng() - LONGITUDE(18567): Row: 10, Values: 4.1023
02-24 12:58:56.025: V/getLng() - LONGITUDE(18567): Row: 11, Values: 3.5628
02-24 12:58:56.026: V/getLng() - LONGITUDE(18567): Row: 12, Values: 3.562
02-24 12:58:56.027: V/getLng() - LONGITUDE(18567): Row: 13, Values: 3.5629
02-24 12:58:56.027: V/getLng() - LONGITUDE(18567): Row: 14, Values: 4.215
02-24 12:58:56.027: V/getLng() - LONGITUDE(18567): Row: 15, Values: 4.1703
02-24 12:58:56.027: V/getLng() - LONGITUDE(18567): Row: 16, Values: 4.1994
02-24 12:58:56.028: V/getLng() - LONGITUDE(18567): Row: 17, Values: 3.2677
02-24 12:58:56.028: V/getLng() - LONGITUDE(18567): Row: 18, Values: 3.2108
02-24 12:58:56.029: V/getLng() - LONGITUDE(18567): Row: 19, Values: 3.7254
答案 0 :(得分：1)
也许我错过了一些东西，但看起来你的getLat（）方法实际上并没有在任何地方设置_lat（它返回的值）的值？同样适用于getLong（）等。
如果这不是问题，您是否尝试过调试并单步执行代码？这应该可以让你更好地了解duff值的来源。
抱歉，我会将此作为评论添加，但没有足够的代表。
答案 1 :(得分：1)
未检索纬度和经度，因为方法getLat()和getLng()从光标检索错误。
由于您只从数据库中选择一列，因此您必须获得列索引0，而不是像在getLat()和getLng()方法中那样获得1或2。
在这些方法中，请执行以下操作：
// getLat() method
_lat = latQuery.getDouble(0);
// getLng() method
_lng = lngQuery.getDouble(0);
答案 2 :(得分：0)
保持数据元组的原因是什么 - lat，lng，description等 - 除了？我把它放在一个有3列的表中（为了简洁起见，其余部分）：
Latitude | Longitude | Description
11.11 | 11.11 | Place A
22.22 | 22.22 | place B
在这种情况下，你永远不会得到像11,11; 22.22; place B这样的记录，你的情况显然会发生什么