我的代码出错，我的数据库文件为空。请检查并告诉我可能的原因。
Database.java：
package com.example.nearby_places;
import java.util.ArrayList;
import java.util.List;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class Database extends SQLiteOpenHelper {
//database name & version number
private static final String db_name = "nearby_places";
private static final int db_version = 1;
//tables
private static final String table_placetypes = "placetypes";
private static final String table_places = "table_places";
//column names
private static final String type_id = "type_id";
private static final String type_name = "type_name";
private static final String place_id = "place_id";
private static final String place_name = "place_name";
private static final String place_address = "place_address";
private static final String place_contact = "place_contact";
public Database(Context context) {
super(context, db_name, null, db_version);
// TODO Auto-generated constructor stub
}
// create table queries
String create_table_placetypes = "CREATE TABLE IF NOT EXISTS " + table_placetypes + "("
+ type_id + " INTEGER PRIMARY KEY NOT NULL," + type_name + " TEXT" + ")";
String create_table_places = "CREATE TABLE IF NOT EXISTS table_places (place_id INTEGER PRIMARY KEY NOT NULL, place_name TEXT, place_address TEXT, place_contact TEXT, type_id FOREIGN KEY (type_id) REFERENCES table_placetypes(type_id))";
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(create_table_placetypes);
Log.d("creating", "placetypes created");
db.execSQL(create_table_places);
Log.d("creating", "places created");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS " + table_placetypes);
db.execSQL("DROP TABLE IF EXISTS " + table_places);
onCreate(db);
}
// add placetypes
void addplacetypes (placetypes pt) {
SQLiteDatabase db = getWritableDatabase();
ContentValues values = new ContentValues();
values.put(type_name, pt.getTypename());
db.insert(table_placetypes, null, values);
db.close();
}
// Getting single placetypes
placetypes getPlacetypes(int id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(table_placetypes, new String[] {type_id,
type_name }, type_id + "=?",
new String[] { String.valueOf(id) }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
placetypes pt = new placetypes(Integer.parseInt(cursor.getString(0)),
cursor.getString(1));
// return contact
return pt;
}
// Getting All placetypes
public List<placetypes> getAllPlacetypes() {
List<placetypes> placetypesList = new ArrayList<placetypes>();
// Select All Query
String selectQuery = "SELECT * FROM " + table_placetypes;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
placetypes pt = new placetypes();
pt.setTypeid(Integer.parseInt(cursor.getString(0)));
pt.setTypename(cursor.getString(1));
//String name = cursor.getString(1);
//MainActivity.ArrayofName.add(name);
// Adding contact to list
placetypesList.add(pt);
} while (cursor.moveToNext());
}
// return placetype list
return placetypesList;
}
// Getting placetypes Count
public int getPlacetypesCount() {
String countQuery = "SELECT * FROM " + table_placetypes;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
cursor.close();
// return count
return cursor.getCount();
}
public void addplaces(places p) {
SQLiteDatabase db = getWritableDatabase();
ContentValues values = new ContentValues();
values.put(place_name, p.getPlace_name());
values.put(place_address, p.getPlace_address());
values.put(place_contact, p.getPlace_contact());
values.put(type_id, p.getT_id());
Log.d("Type ID", String.valueOf(p.getT_id()));
db.insert(table_places, null, values);
db.close();
}
places getPlaces(int pid) {
SQLiteDatabase db = getReadableDatabase();
Cursor cursor = db.query(table_places, new String[] {place_id, place_name, place_address, place_contact,type_id}, place_id + "=?", new String[] { String.valueOf(pid) } , null, null, null, null);
if(cursor != null)
cursor.moveToFirst();
places p = new places(Integer.parseInt(cursor.getString(0)),
Integer.parseInt(cursor.getString(1)),
cursor.getString(2),
cursor.getString(3),
cursor.getString(4)
);
cursor.close();
return p;
}
public List<places> getAllPlaces(String typeName) {
List<places> placeList = new ArrayList<places>();
//String selectQuery = "SELECT * FROM table_places INNER JOIN placetypes ON placetypes.type_id=table_places.type_id ";
//String selectQuery = "SELECT * FROM table_places WHERE table_places.type_id="+Integer.toString(typeid);
String selectQuery ="SELECT * FROM table_places WHERE placetypes.place_name="+typeName+" INNER JOIN placetypes ON placetypes.type_id=table_places.type_id";
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if(cursor.moveToFirst() )
{
do{
places p = new places();
/*p.setT_id(cursor.getColumnIndex(type_id));
p.setPlace_id(cursor.getColumnIndex(place_id));
p.setPlace_name(cursor.getColumnIndex(place_name));
*/
p.setT_id(cursor.getInt(0));
p.setPlace_id(cursor.getInt(1));
p.setPlace_name(cursor.getString(2));
p.setPlace_address(cursor.getString(3));
p.setPlace_contact(cursor.getString(4));
/*String t_id = cursor.getString(4);
String p_name = cursor.getString(2);
String p_address = cursor.getString(3);
String p_contact = cursor.getString(1);*/
placeList.add(p);
}while(cursor.moveToNext());
}
cursor.close();
return placeList;
}
public int getPlaceCount () {
String selectQuery = "SELECT * FROM " +table_places;
SQLiteDatabase db = getReadableDatabase();
Cursor cursor = db.rawQuery(create_table_places, null);
cursor.close();
return cursor.getCount();
}
}
logcat的
10-11 05:11:27.479: D/dalvikvm(3671): GC_FOR_ALLOC freed 45K, 10% free 2728K/3004K, paused 270ms, total 274ms
10-11 05:11:27.689: I/dalvikvm-heap(3671): Grow heap (frag case) to 3.959MB for 1127532-byte allocation
10-11 05:11:27.959: D/dalvikvm(3671): GC_FOR_ALLOC freed 2K, 7% free 3826K/4108K, paused 268ms, total 268ms
10-11 05:11:30.049: D/creating(3671): placetypes created
10-11 05:11:30.099: E/SQLiteLog(3671): (1) near "FOREIGN": syntax error
10-11 05:11:30.309: D/AndroidRuntime(3671): Shutting down VM
10-11 05:11:30.309: W/dalvikvm(3671): threadid=1: thread exiting with uncaught exception (group=0xb0f3c648)
10-11 05:11:30.469: E/AndroidRuntime(3671): FATAL EXCEPTION: main
10-11 05:11:30.469: E/AndroidRuntime(3671): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nearby_places/com.example.nearby_places.MainActivity}: android.database.sqlite.SQLiteException: near "FOREIGN": syntax error (code 1): , while compiling: CREATE TABLE IF NOT EXISTS table_places (place_id INTEGER PRIMARY KEY NOT NULL, place_name TEXT, place_address TEXT, place_contact TEXT, type_id FOREIGN KEY (type_id) REFERENCES table_placetypes(type_id))
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.os.Handler.dispatchMessage(Handler.java:99)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.os.Looper.loop(Looper.java:137)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.app.ActivityThread.main(ActivityThread.java:5103)
10-11 05:11:30.469: E/AndroidRuntime(3671): at java.lang.reflect.Method.invokeNative(Native Method)
10-11 05:11:30.469: E/AndroidRuntime(3671): at java.lang.reflect.Method.invoke(Method.java:525)
10-11 05:11:30.469: E/AndroidRuntime(3671): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
10-11 05:11:30.469: E/AndroidRuntime(3671): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-11 05:11:30.469: E/AndroidRuntime(3671): at dalvik.system.NativeStart.main(Native Method)
10-11 05:11:30.469: E/AndroidRuntime(3671): Caused by: android.database.sqlite.SQLiteException: near "FOREIGN": syntax error (code 1): , while compiling: CREATE TABLE IF NOT EXISTS table_places (place_id INTEGER PRIMARY KEY NOT NULL, place_name TEXT, place_address TEXT, place_contact TEXT, type_id FOREIGN KEY (type_id) REFERENCES table_placetypes(type_id))
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1672)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1603)
10-11 05:11:30.469: E/AndroidRuntime(3671): at com.example.nearby_places.Database.onCreate(Database.java:55)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:252)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
10-11 05:11:30.469: E/AndroidRuntime(3671): at com.example.nearby_places.Database.getAllPlacetypes(Database.java:105)
10-11 05:11:30.469: E/AndroidRuntime(3671): at com.example.nearby_places.MainActivity.onCreate(MainActivity.java:29)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.app.Activity.performCreate(Activity.java:5133)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-11 05:11:30.469: E/AndroidRuntime(3671): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
10-11 05:11:30.469: E/AndroidRuntime(3671): ... 11 more
答案 0 :(得分：0)
create_table_places应该是
String create_table_places = "CREATE TABLE IF NOT EXISTS table_places (place_id INTEGER PRIMARY KEY NOT NULL, place_name TEXT, place_address TEXT, place_contact TEXT, type_id INTEGER, FOREIGN KEY (type_id) REFERENCES table_placetypes(type_id))";