安卓：从数据库中获取的Widget数据数据库中、数据、Widget

2023-09-06 07:20:15 作者：傲气稳了全场

我想打一个主屏幕，控件，它显示一个随机收到一个数据库。其实我得到了它打开数据库命令错误。

所以，我能做些什么，使工作？在一个正常的活动通常这code的工作....但小窗口？

 包com.droidfish.apps.acli;

导入了java.util.Random;

进口android.appwidget.AppWidgetManager;
进口android.appwidget.AppWidgetProvider;
进口android.content.Context;
进口android.database.Cursor;
进口android.util.Log;
进口android.widget.RemoteViews;
进口android.widget.Toast;

公共类RecieptOfTheDayWidget扩展AppWidgetProvider {
静态DataBaseHelper胸径;

公共无效onDeleted（上下文的背景下，INT [] appWidgetIds）{
    // TODO自动生成方法存根
    super.onDeleted（背景下，appWidgetIds）;
    Toast.makeText（背景下，小工具已删除，Toast.LENGTH_SHORT）.show（）;
}

@覆盖
公共无效的OnUpdate（上下文的背景下，AppWidgetManager appWidgetManager，
        INT [] appWidgetIds）{
    // TODO自动生成方法存根
    super.onUpdate（背景下，appWidgetManager，appWidgetIds）;

    最终诠释IN = appWidgetIds.length;

    updateWidgetContent（背景下，appWidgetManager，appWidgetIds）;
}

公共静态无效updateWidgetContent（上下文的背景下，
        AppWidgetManager appWidgetManager，INT [] appWidgetIds）{
    dbh.openDataBase（）;
    字符串sNameVariant =basestring的;
    游标c1 = dbh.rawQuery（选择从收据_id）;
    随机R =新的随机（）;
    INT iRandomID = 1;
    INT iVName = c1.getColumnIndex（姓名）;
    INT iCountDataSet;
    为（c1.moveToFirst（）;！c1.isAfterLast（）; c1.moveToNext（））{
        iCountDataSet = c1.getCount（）;
        iRandomID = r.nextInt（iCountDataSet）;
        Log.d（随机，（Integer.toString（iRandomID）））;

    }
    游标c2 =胸径
            .rawQuery（FROM收据SELECT name其中_id =
                    + iRandomID）;
    为（c2.moveToFirst（）;！c2.isAfterLast（）; c2.moveToNext（））{
        sNameVariant = c2.getString（iVName）;
    }
    RemoteViews vView1 =新RemoteViews（context.getPackageName（）
            R.layout.recieptofthedaywidget）;

    vView1.setTextViewText（R.id.tvWidgetReciept，sNameVariant）;
    dbh.close（）;

    appWidgetManager.updateAppWidget（appWidgetIds，vView1）;
}
}

感谢彼得

更新＃1：感谢柯蒂斯，

我添加了这样的方法

 私有静态DataBaseHelper getDatabaseHelper（上下文的背景下）{
    DataBaseHelper胸径= NULL;
    如果（胸径== NULL）{
        胸径=新DataBaseHelper（上下文）;
        dbh.openDataBase（）;
    }
    返回胸径;
}

但现在收到这个错误

  8月10号至三十零日：32：53.882：E / AndroidRuntime（296）：java.lang.RuntimeException的：无法启动接收器com.droidfish.apps.acli.RecieptOfTheDayWidget：JAVA。 lang.IllegalStateException：获得现场插槽从第0山坳-1失败

看起来其无法从列计数的范围内的随机数。这是正确的吗？实际上，它产生了同样的错误，当我写

  iRandomID = r.nextInt（3）;

MHH那真的很有趣。有什么建议么？

更新＃2：我改变了我的code这样的，它的工作。有索姆重要的线缺失：））））

再次感谢

 游标c1 = getDatabaseHelper（上下文）.getReadableDatabase（）rawQuery（选择从reciept_variant _id，NULL）;
    随机R =新的随机（）;
    INT iRandomID = 1;
    INT iVName = c1.getColumnIndex（_ ID）;
    INT iCountDataSet;
    为（c1.moveToFirst（）;！c1.isAfterLast（）; c1.moveToNext（））{
        iCountDataSet = c1.getCount（）;
        // iRandomID = r.nextInt（3）;
        iRandomID = r.nextInt（iCountDataSet）;
        Log.d（随机，（Integer.toString（iRandomID）））;

    }
    游标c2 = getDatabaseHelper（上下文）.getReadableDatabase（）。rawQuery（选择_id从reciept_variant名在_id = 3
                ， 空值）;

    INT iName2 = c2.getColumnIndex（姓名）;
    为（c2.moveToFirst（）;！c2.isAfterLast（）; c2.moveToNext（））{
        sNameVariant = c2.getString（iName2）;
    }

解决方案

彼得，它看起来像你从来没有初始化数据库辅助类。因此，它被设置为空，你可能会得到一个空指针异常。尝试添加以下code：

 私有静态DataBaseHelper getDatabaseHelper（）{
  如果（胸径== NULL）{
     胸径=新DatabaseHelper（/ *把你的数据库的辅助参数在这里* /）;
     dbh.openDatabase（）;
  }
  返回胸径;
}

然后，每当你需要使用的胸径，你叫getDatabaseHelper。例如，在你updateWidgetContent（）方法做到这一点：

 游标c1 = getDatabaseHelper（）getReadableDatabase（）rawQuery（选择从收据_id）。

I want to make a homescreen-widget which displays a random Receipt from a database. Actually I got an error on the command which opens the database.

So what I can do to make it work? Usually this code work in a normal activity....but as widget??

package com.droidfish.apps.acli;

import java.util.Random;

import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.database.Cursor;
import android.util.Log;
import android.widget.RemoteViews;
import android.widget.Toast;

public class RecieptOfTheDayWidget extends AppWidgetProvider {
static DataBaseHelper dbh;

public void onDeleted(Context context, int[] appWidgetIds) {
    // TODO Auto-generated method stub
    super.onDeleted(context, appWidgetIds);
    Toast.makeText(context, "widget deleted", Toast.LENGTH_SHORT).show();
}

@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager,
        int[] appWidgetIds) {
    // TODO Auto-generated method stub
    super.onUpdate(context, appWidgetManager, appWidgetIds);

    final int iN = appWidgetIds.length;

    updateWidgetContent(context, appWidgetManager, appWidgetIds);
}

public static void updateWidgetContent(Context context,
        AppWidgetManager appWidgetManager, int[] appWidgetIds) {
    dbh.openDataBase();
    String sNameVariant = "basestring";
    Cursor c1 = dbh.rawQuery("SELECT _id from reciept");
    Random r = new Random();
    int iRandomID = 1;
    int iVName = c1.getColumnIndex("name");
    int iCountDataSet;
    for (c1.moveToFirst(); !c1.isAfterLast(); c1.moveToNext()) {
        iCountDataSet = c1.getCount();
        iRandomID = r.nextInt(iCountDataSet);
        Log.d("Random: ", (Integer.toString(iRandomID)));

    }
    Cursor c2 = dbh
            .rawQuery("SELECT name FROM reciept WHERE _id = "
                    + iRandomID);
    for (c2.moveToFirst(); !c2.isAfterLast(); c2.moveToNext()) {
        sNameVariant = c2.getString(iVName);
    }
    RemoteViews vView1 = new RemoteViews(context.getPackageName(),
            R.layout.recieptofthedaywidget);

    vView1.setTextViewText(R.id.tvWidgetReciept, sNameVariant);
    dbh.close();

    appWidgetManager.updateAppWidget(appWidgetIds, vView1);
}
}

Thanks Peter

UPDATE #1: Thanks Curtis,

i added your method like this

    private static DataBaseHelper getDatabaseHelper(Context context) {
    DataBaseHelper dbh = null;
    if (dbh == null) {
        dbh = new DataBaseHelper(context);
        dbh.openDataBase();
    }
    return dbh;
}

but now getting this error

10-30 08:32:53.882: E/AndroidRuntime(296): java.lang.RuntimeException: Unable to start receiver com.droidfish.apps.acli.RecieptOfTheDayWidget: java.lang.IllegalStateException: get field slot from row 0 col -1 failed

It looks like its unable to get a Random number from the range of the column count. Is this right? Actually it produce the same error when i write

iRandomID = r.nextInt(3);

Mhh thats really interesting. Any suggestions?

UPDATE #2: I changed my code like this and it work. There were som important lines missing :))))

Thanks again

        Cursor c1 =getDatabaseHelper(context).getReadableDatabase().rawQuery("SELECT _id from reciept_variant", null);
    Random r = new Random();
    int iRandomID = 1;
    int iVName = c1.getColumnIndex("_id");
    int iCountDataSet;
    for (c1.moveToFirst(); !c1.isAfterLast(); c1.moveToNext()) {
        iCountDataSet = c1.getCount();
        //iRandomID = r.nextInt(3);
        iRandomID = r.nextInt(iCountDataSet);
        Log.d("Random: ", (Integer.toString(iRandomID)));

    }
    Cursor c2 = getDatabaseHelper(context).getReadableDatabase().rawQuery("SELECT _id, name FROM reciept_variant WHERE _id = 3"
                , null);

    int iName2 = c2.getColumnIndex("name");
    for (c2.moveToFirst(); !c2.isAfterLast(); c2.moveToNext()) {
        sNameVariant = c2.getString(iName2);
    }

解决方案

Peter, it looks like you never initialize your Database helper class. It is therefore set to null and you're probably getting a null pointer exception. Try adding the following code:

private static DataBaseHelper getDatabaseHelper(){
  if(dbh==null){
     dbh = new DatabaseHelper(/* put your database helper arguments here */);
     dbh.openDatabase();
  }
  return dbh;
}

Then whenever you need to use the dbh, you call getDatabaseHelper. For instance, in you updateWidgetContent() method do this:

 Cursor c1 = getDatabaseHelper().getReadableDatabase().rawQuery("SELECT _id from reciept");

上一篇：问题解决机器人工作室gradle这个依赖？机器人、工作室、问题、gradle

下一篇：如何实现从一个保留片段主办的异步任务坚持更改UI？如何实现、片段、任务、UI

相关推荐

精彩图集

精彩推荐

图片推荐

家里搁一物千万于没甲由科学灭除甲由的