数据库第一次没有填写

Question

我将通过 JSON 从服务器获取一些数据，并将它们存储在我的 sqlite 数据库中。

当我使用下面的代码时，在第一次时， Toast 消息显示我的表格行零。

但是当我运行 second 时间的应用程序时，它会显示当前的数字（JSON数据计数）。

此外，在第二时间，我删除了他们将数据存储到 sqlite 数据库的行并运行应用程序，以确保在第一个 strong>时间数据存储在数据库中。

请让我知道我哪里错了......

AboutActivity：

public class AboutActivity extends ActionBarActivity implements OnClickListener, OnItemClickListener {

DBHandler dbh;
private static final String TAG_IMAGES = "images";
private static final String TAG_GUID = "GUID";
private static final String TAG_IMG_LINK = "img_link";
private static final String TAG_IMG_DESC = "img_desc";
private static final String TAG_URL = "http://xxx/x.php";
private JSONArray jArray = null;
private JSONParser jParser;
private JSONObject jObject;
private ProgressDialog pDialog;

String[] GUID;
String[] imgLink;
String[] imgDesc;
String[] imgPath;
AboutSlideShowModel model;

@Override
protected void onCreate(Bundle savedInstanceState) 
{
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_about);

    dbh = new DBHandler(AboutActivity.this);

    getAllDataFromServer myClass =  new getAllDataFromServer();
    myClass.execute();
    Toast.makeText(AboutActivity.this, dbh.getCount() + "", 5000).show();
}

private class getAllDataFromServer extends AsyncTask<Void, Void, Void>
{
    @Override
    protected void onPreExecute() 
    {
        pDialog = new ProgressDialog(AboutActivity.this);
        pDialog.setMessage("Be patient ...");
        pDialog.show();
        super.onPreExecute();
    }

    @Override
    protected Void doInBackground(Void... params) 
    {
        jParser = new JSONParser();
        jObject = jParser.getJSONFromUrl(TAG_URL);
        try
        {
            jArray = jObject.getJSONArray(TAG_IMAGES);
            GUID = new String[jArray.length()];
            imgLink = new String[jArray.length()];
            imgPath = new String[jArray.length()];
            imgDesc = new String[jArray.length()];
            for(int i=0; i<jArray.length(); i++)
            {
                JSONObject tempJson = jArray.getJSONObject(i);
                GUID[i] = tempJson.getString(TAG_GUID);
                imgLink[i] = tempJson.getString(TAG_IMG_LINK);
                imgDesc[i] = tempJson.getString(TAG_IMG_DESC);
                new SaveImageIntoStorage(AboutActivity.this, imgLink[i], GUID[i] + ".jpg", "SlideShow").saveImage();
                imgPath[i] = Environment.getExternalStorageDirectory() + "/Slideshow/" + GUID[i] + ".jpg";
                model = new AboutSlideShowModel(GUID[i], imgLink[i], imgPath[i], imgDesc[i]);
                dbh.insertSingleAboutSlideShow(model);
            }
        }
        catch(JSONException e)
        {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void result) 
    {
        pDialog.dismiss();
        super.onPostExecute(result);
    }
    }
}

AboutSlideShowModel：

public class AboutSlideShowModel 
{
public int ID;
public String GUID;
public String IMG_LINK;
public String IMG_PATH;
public String Description;

public AboutSlideShowModel() {}

public AboutSlideShowModel(int ID, String GUID, String IMG_LINK, String    IMG_PATH, String Description)
{
    this.GUID = GUID;
    this.IMG_LINK = IMG_LINK;
    this.IMG_PATH = IMG_PATH;
    this.Description = Description;
    this.ID = ID;
}

public AboutSlideShowModel(String GUID, String IMG_LINK, String IMG_PATH, String Description)
{
    this.GUID = GUID;
    this.IMG_LINK = IMG_LINK;
    this.IMG_PATH = IMG_PATH;
    this.Description = Description;
}

public void setID(int ID)
{
    this.ID = ID;
}

public void setGUID(String GUID)
{
    this.GUID = GUID;
}

public void setIMG_LINK(String IMG_LINK)
{
    this.IMG_LINK = IMG_LINK;
}

public void setIMG_PATH(String IMG_PATH)
{
    this.IMG_PATH = IMG_PATH;
}

public void setDescription(String Description)
{
    this.Description = Description;
}

public int getID()
{
    return this.ID;
}

public String getGUID()
{
    return this.GUID;
}

public String getIMG_LINK()
{
    return this.IMG_LINK;
}

public String getIMG_PATH()
{
    return this.IMG_PATH;
}

public String getDescription()
{
    return this.Description;
}
}

DBHandler：

public class DBHandler extends SQLiteOpenHelper 
{
private static final String DB_NAME = "db";
private static final int DB_VERSION = 1;

private static final String KEY_ID = "id";
private static final String KEY_GUID = "guid";
private static final String KEY_IMAGE_PATH = "image_path";
private static final String KEY_IMAGE_LINK = "image_link";
private static final String KEY_DESCRIPTION = "description";

private static final String TBL_ABOUT_SLIDESHOW = "tbl_about_slideshow";

private static final String CREATE_TBL_ABOUT_SLIDESHOW = "CREATE TABLE IF NOT EXISTS "
        + TBL_ABOUT_SLIDESHOW + "("
        + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
        + KEY_GUID + " TEXT," 
        + KEY_IMAGE_LINK + " TEXT," 
        + KEY_IMAGE_PATH + " TEXT," 
        + KEY_DESCRIPTION + " TEXT" + ")";

public DBHandler(Context context) 
{
    super(context, DB_NAME, null, DB_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) 
{
    db.execSQL(CREATE_TBL_ABOUT_SLIDESHOW);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) 
{
    db.execSQL("DROP TABLE IF EXISTS " + TBL_ABOUT_SLIDESHOW);
    onCreate(db);
}

public void insertSingleAboutSlideShow(AboutSlideShowModel model)
{
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(KEY_GUID, model.getGUID());
    values.put(KEY_IMAGE_LINK, model.getIMG_LINK());
    values.put(KEY_IMAGE_PATH, model.getIMG_PATH());
    values.put(KEY_DESCRIPTION, model.getDescription());
    // Inserting Row
    db.insert(TBL_ABOUT_SLIDESHOW, null, values);
    db.close(); // Closing database connection
}
public int getCount()
{
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor c = db.rawQuery("SELECT * FROM " + TBL_ABOUT_SLIDESHOW, null);
    if(c.getCount() <= 0)
        return 0;
    return c.getCount();
}
}

Answer 1

您的任务正在异步执行，因此当您执行toast时，AsyncTask尚未检索到数据。如果您使用onPostExecute方法检查数据库，则可能会看到您要查找的结果。