Java “为什么我会这样?”;不兼容类型:Bla无法转换为上下文;在我的SQLiteOpenHelper构造函数中?
我正在我的Android项目中实现SQLite功能,使用 我有以下SQLiteOpenHelper代码:Java “为什么我会这样?”;不兼容类型:Bla无法转换为上下文;在我的SQLiteOpenHelper构造函数中?,java,android,sqlite,android-sqlite,sqliteopenhelper,Java,Android,Sqlite,Android Sqlite,Sqliteopenhelper,我正在我的Android项目中实现SQLite功能,使用 我有以下SQLiteOpenHelper代码: public class HHSSQLiteHandler extends SQLiteOpenHelper { private static final int DATABASE_VERSION = 1; private static final String DATABASE_NAME = "HHS.db"; private static final Strin
public class HHSSQLiteHandler extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "HHS.db";
private static final String TABLE_VENDORS = "vendors";
public static final String COLUMN_ID = "_id";
public static final String COLUMN_VENDORID = "vendorId";
public static final String COLUMN_COMPANYNAME = "companyName";
public HHSSQLiteHandler(Context context, String vendor,
SQLiteDatabase.CursorFactory factory, int company) {
super(context, DATABASE_NAME, factory, DATABASE_VERSION);
}
. . .
…但尝试以这种方式实例化该类:
protected void onPostExecute(String result) {
try {
JSONArray jsonArr = new JSONArray(result);
for (int i = 0; i < jsonArr.length(); i++) {
JSONObject jsonObj = jsonArr.getJSONObject(i);
String vendorId = jsonObj.getString("vendorId");
String companyName = jsonObj.getString("companyName");
// Prepare for writing to db
Vendor vend = new Vendor();
vend.setVendorId(vendorId);
vend.setCompanyName(companyName);
HHSSQLiteHandler sqliteHandler = new HHSSQLiteHandler(this, null, null, 1);
sqliteHandler.addVendor(vend);
}
} catch (JSONException j) {
System.out.println(j.getMessage());
Log.i("jsonEx", j.getMessage());
}
}
受保护的void onPostExecute(字符串结果){
试一试{
JSONArray jsonArr=新JSONArray(结果);
for(int i=0;i
…在“HHSSQLiteHandler sqliteHandler=new HHSSQLiteHandler(this,null,null,1);”行上给出“错误:不兼容的类型:MainActivity.GetVendorTask无法转换为上下文”
它到底在期待什么?我应该通过什么来安抚它
嵌套类中的此
引用嵌套类实例(GetVendorTask
),而不是外部类实例(MainActivity
)。使用例如main活动对其进行限定。此
引用外部类实例,如果它是上下文
(例如活动
),则它将起作用