在33行insert()方法中 怎样实例化dbHelper 改半天了 也不对 import android.content.ContentProvider;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.net.Uri;public class DataProvider extends ContentProvider {
public static final String DATABASE_NAME = "crmdb.db";
public static final int DATABASE_VERSION = 5;
public static final String CLIENT_TABLE_NAME = "Client";
public static final String AUTHORITY = "com.rl.crm";
public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY
+ "/" + CLIENT_TABLE_NAME);
@Override
public int delete(Uri arg0, String arg1, String[] arg2) {
// TODO Auto-generated method stub
return 0;
} @Override
public String getType(Uri uri) {
// TODO Auto-generated method stub
return null;
} @Override
public Uri insert(Uri uri, ContentValues values) {
SQLiteOpenHelper dbHelper = new DBHelper(this);
SQLiteDatabase db = dbHelper.getReadableDatabase();
long rowId = db.insert(CLIENT_TABLE_NAME, null, values);
if (rowId > 0) {
// 插入成功
return null;
} else {
// 插入失败
throw new SQLException("插入失败" + uri);
}
}
@Override
public boolean onCreate() {
// TODO Auto-generated method stub
return false;
} @Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// TODO Auto-generated method stub
return null;
} @Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
// TODO Auto-generated method stub
return 0;
}}
import android.content.ContentValues;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.net.Uri;public class DataProvider extends ContentProvider {
public static final String DATABASE_NAME = "crmdb.db";
public static final int DATABASE_VERSION = 5;
public static final String CLIENT_TABLE_NAME = "Client";
public static final String AUTHORITY = "com.rl.crm";
public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY
+ "/" + CLIENT_TABLE_NAME);
@Override
public int delete(Uri arg0, String arg1, String[] arg2) {
// TODO Auto-generated method stub
return 0;
} @Override
public String getType(Uri uri) {
// TODO Auto-generated method stub
return null;
} @Override
public Uri insert(Uri uri, ContentValues values) {
SQLiteOpenHelper dbHelper = new DBHelper(this);
SQLiteDatabase db = dbHelper.getReadableDatabase();
long rowId = db.insert(CLIENT_TABLE_NAME, null, values);
if (rowId > 0) {
// 插入成功
return null;
} else {
// 插入失败
throw new SQLException("插入失败" + uri);
}
}
@Override
public boolean onCreate() {
// TODO Auto-generated method stub
return false;
} @Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// TODO Auto-generated method stub
return null;
} @Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
// TODO Auto-generated method stub
return 0;
}}
SQLiteDatabase db = dbHelper.getReadableDatabase();这两句最好放在onCreate里面吧,dbHelper db 可以设为类的成员变量。
DBHelper dbHelper;
SQLiteDatabase db = dbHelper.getReadableDatabase();
但是那样会报SQLiteDatabase db = dbHelper.getReadableDatabase();这句空指针 怎么弄啊
dbHelper没实例化,当然是空的了。
SQLiteOpenHelper dbHelper = new DBHelper(this);
SQLiteDatabase db = dbHelper.getReadableDatabase();不允许这种实例化 楼上说一般不这么写 但是我不知道怎么写 帮下忙吧~