Question

在我的项目中，我的Fragment是ListFragment。到目前为止，我所做的是使用来自SQLite数据库的数据填充List;但现在，我正面临着这个问题：

如果我的数据库中没有数据，我的ListFragment将为空;这就是为什么我想用一张图片来代替列表。

现在，我仍然坚持如何在onCreateView中使用ListFragment。

我发现的一个替代方案是：“使用Fragment代替ListFragment”

有没有其他方法可以做到这一点，而没有用ListFragment替换Fragment？

编辑1

这属于doInBackGround：

Conexion = new MarketSQLite(getActivity(), "market", null, 1);
mItems = new ArrayList<ListViewItem>();
db = Conexion.getReadableDatabase();

Cursor c;
c = db.rawQuery("Select NOM_OFER,PREU_OFERTA,DATA_F,FOTO,PERCENTDESCOMPTE from T_OFERTA", null);
c.moveToFirst();
// HERE'S NOT NULL, SO I CAN PUT SOME STUFF
if (c != null) {
    do {
        for (int i = 0; i < c.getColumnCount(); i++) {
            Title = c.getString((c.getColumnIndex("NOM_OFER")));
            Preu = c.getColumnIndex("PREU_OFERTA");
            percent = c.getString((c.getColumnIndex("PERCENTDESCOMPTE")));
            data_f = c.getString((c.getColumnIndex("DATA_F")));
            URLTest = c.getString((c.getColumnIndex("FOTO")));
            Log.e("", "" + c.getString(i));

            // initialize and set the list adapter
            // Toast.makeText(getActivity(), "Title" + Title + "Preu" + Preu + "Percent" + percent + "Cheese is " + data_f, Toast.LENGTH_LONG).show();
        }

        mItems.add(new ListViewItem(URLTest, Title, Preu.toString(), percent, data_f));
    } while (c.moveToNext());
}

if (c== null) {
    getListView().setEmptyView(getActivity().findViewById(R.id.layout_empty));
    // HERE I WANT TO ADD IMAGEVIEW CAUSE C IS NULL THEN THE FRAGMENT WON'T BE EMPTY
}
c.close();

这就是我所面临的错误：

java.lang.RuntimeException: An error occured while executing doInBackground()
    at android.os.AsyncTask$3.done(AsyncTask.java:300)
    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
    at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
    at java.util.concurrent.FutureTask.run(FutureTask.java:242)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:841)
Caused by: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0
    at android.database.AbstractCursor.checkPosition(AbstractCursor.java:426)
    at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:136)
    at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:50)
    at info.androidhive.slidingmenu.MisOfertasFragment$MyAsyncTask.doInBackground(MisOfertasFragment.java:108)
    at info.androidhive.slidingmenu.MisOfertasFragment$MyAsyncTask.doInBackground(MisOfertasFragment.java:86)
    at android.os.AsyncTask$2.call(AsyncTask.java:288)
    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:841)

编辑2

我用光标做了一些更改。我删除了SQLite上的一些数据，以测试它是否有效;但现在，它没有显示任何内容。

Cursor c;
c = db.rawQuery("Select NOM_OFER,PREU_OFERTA,DATA_F,FOTO,PERCENTDESCOMPTE from T_OFERTA", null);

//HERE'S NOT NULL, SO I CAN PUT SOME STUFF
if (c.moveToFirst()) {
    do {
        for (int i = 0; i < c.getColumnCount(); i++) {
            Title = c.getString((c.getColumnIndex("NOM_OFER")));
            Preu = c.getColumnIndex("PREU_OFERTA");
            percent = c.getString((c.getColumnIndex("PERCENTDESCOMPTE")));
            data_f = c.getString((c.getColumnIndex("DATA_F")));
            URLTest = c.getString((c.getColumnIndex("FOTO")));
            Log.e("", "" + c.getString(i));

            // initialize and set the list adapter
            // Toast.makeText(getActivity(), "Title" + Title + "Preu" + Preu + "Percent" + percent + "Cheese is " + data_f, Toast.LENGTH_LONG).show();
        }

        mItems.add(new ListViewItem(URLTest, Title, Preu.toString(), percent, data_f));
    } while (c.isAfterLast());
}

if (!c.moveToFirst()) {
    Log.d("No registres","pewpew");

    // HERE I WANT TO ADD IMAGEVIEW CAUSE C IS NULL THEN THE FRAGMENT WON'T BE EMPTY
}
c.close();

Answer 1

尝试替换

Cursor c;
c = db.rawQuery("Select NOM_OFER,PREU_OFERTA,DATA_F,FOTO,PERCENTDESCOMPTE from T_OFERTA", null);

//HERE'S NOT NULL, SO I CAN PUT SOME STUFF
if (c.moveToFirst()) {
    do {
        for (int i = 0; i < c.getColumnCount(); i++) {
            Title = c.getString((c.getColumnIndex("NOM_OFER")));
            Preu = c.getColumnIndex("PREU_OFERTA");
            percent = c.getString((c.getColumnIndex("PERCENTDESCOMPTE")));
            data_f = c.getString((c.getColumnIndex("DATA_F")));
            URLTest = c.getString((c.getColumnIndex("FOTO")));
            Log.e("", "" + c.getString(i));

            // initialize and set the list adapter
            // Toast.makeText(getActivity(), "Title" + Title + "Preu" + Preu + "Percent" + percent + "Cheese is " + data_f, Toast.LENGTH_LONG).show();
        }

        mItems.add(new ListViewItem(URLTest, Title, Preu.toString(), percent, data_f));
    } while (c.isAfterLast());
}

if (!c.moveToFirst()) {
    Log.d("No registres","pewpew");

    // HERE I WANT TO ADD IMAGEVIEW CAUSE C IS NULL THEN THE FRAGMENT WON'T BE EMPTY
}
c.close();

要

Cursor c;
c = db.rawQuery("Select NOM_OFER,PREU_OFERTA,DATA_F,FOTO,PERCENTDESCOMPTE from T_OFERTA", null);

//HERE'S NOT NULL, SO I CAN PUT SOME STUFF
if (c.moveToFirst()) {
    do {

            Title = c.getString((c.getColumnIndex("NOM_OFER")));
            Preu = c.getColumnIndex("PREU_OFERTA");
            percent = c.getString((c.getColumnIndex("PERCENTDESCOMPTE")));
            data_f = c.getString((c.getColumnIndex("DATA_F")));
            URLTest = c.getString((c.getColumnIndex("FOTO")));


        mItems.add(new ListViewItem(URLTest, Title, Preu.toString(), percent, data_f));
    } while (c.moveToNext());
}

if (!c.moveToFirst()) {
    Log.d("No registres","pewpew");

    // HERE I WANT TO ADD IMAGEVIEW CAUSE C IS NULL THEN THE FRAGMENT WON'T BE EMPTY
}
c.close();

并把它 -

getListView().setEmptyView(findViewById(R.id.layout_empty));

在调用setListAdapter之前。

让我们看看，如果可行的话。

Answer 2

如果我理解正确 - 你可以让你的布局看起来像这样。如果listview为空，则具有此ID的ImageView将显示在页面的中心

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ListView
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:dividerHeight="1px"
        android:paddingLeft="3dp"
        android:paddingRight="3dp">
    </ListView>

    <ImageView
        android:id="@android:id/empty"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>
<!-- Maybe some your stuff here --> 
</LinearLayout>

Answer 3

嗨如果扩展列表片段并希望在列表视图为空时设置图像视图。 android提供set empty view方法，用于在列表视图没有数据时显示视图。请参阅下面的如何设置空视图。

下面是我的列表片段的布局布局内容图像视图的空布局，当列表视图没有要显示的内容时将显示。实际上它总是隐藏在列表视图后面。

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:orientation="vertical"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:paddingLeft="8dp"
         android:paddingRight="8dp">

     <ListView 
           android:id="@id/android:list"
           android:layout_width="match_parent"
           android:layout_height="match_parent"
           android:background="#00FF00"/>

      <include layout="@android:layout/empty_content" />
 </LinearLayout>

empty_content.xml

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:id="@+id/layout_empty"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_gravity="center" >

  <ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/ic_app_logo" />

</LinearLayout>

在java代码中打开列表片段，在片段中添加以下行。

getListView().setEmptyView(findViewById(R.id.layout_empty));

可以在ListFragment中以编程方式添加ImageView吗？

编辑1

编辑2

3 个答案: