怎么实现SQLiteOpenHelper？

代码是这样：
import SQLiteOpenHelper from 'android.database.sqlite.SQLiteOpenHelper';
import SQLiteDatabase from 'android.database.sqlite.SQLiteDatabase';
import Context from 'android.content.Context';
export class XyDBHelper extends SQLiteOpenHelper {

private static TABLE_NAME : String = "xy_search_list"  
private static TABLE_VERSION : Number = 1  

private static COLUMN_ID = 'id'  
private static COLUMN_DESC = 'desc'  
private static COLUMN_URL = 'url'  
private static COLUMN_CREATE_TIME = 'create_time'  

constructor(context : Context) {  
    super(context, XyDBHelper.TABLE_NAME, null, XyDBHelper.TABLE_VERSION)  
}  

override onCreate(db : SQLiteDatabase) {  
}  

public override onUpgrade(param0 : SQLiteDatabase, param1 : number, param2 : number) {  
    // console.log('onUpgrade',param1,param2)  
    // param0.execSQL("DROP TABLE IF EXISTS "+XyDBHelper.TABLE_NAME)  
    // this.onCreate(param0)  
}  

}
但是编译出错，我在java是可以用的

'XyDBHelper' is not abstract and does not implement abstract base class member public abstract fun onUpgrade(p0: SQLiteDatabase!, p1: Int, p2: Int): Unit defined in android.database.sqlite.SQLiteOpenHelper‌

rror: None of the following functions can be called with the arguments supplied: ‌
17:14:13.098 ‌public constructor SQLiteOpenHelper(p0: Context?, p1: String?, p2: SQLiteDatabase.CursorFactory?, p3: Int) defined in android.database.sqlite.SQLiteOpenHelper‌
17:14:13.110 ‌public constructor SQLiteOpenHelper(p0: Context?, p1: String?, p2: Int, p3: SQLiteDatabase.OpenParams) defined in android.database.sqlite.SQLiteOpenHelper‌

‌error: 'onUpgrade' overrides nothing‌
真是炸裂