可以在 ListFragment 上以编程方式添加 ImageView 吗？

Question

在我的项目中，我有一个Fragment，即ListFragment。到目前为止我所做的是用来自SQLite 数据库的数据填充列表；但现在，我面临这个问题：

如果数据库中没有数据，我的ListFragment 将为空；这就是为什么我想用图片代替列表。

现在，我被困在如何在我的ListFragment 中使用onCreateView。

我发现的一种替代方法是：“使用Fragment 而不是ListFragment”

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

编辑 1

这在doInBackGround内部：

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

我对光标进行了一些更改。我删除了我的SQLite 上的一些数据以测试它是否有效；但现在，它什么也没显示。

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();

到

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();

然后放这个 -

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

在调用 setListAdapter 之前。

让我们看看，是否可行。

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，则具有此类 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

您好，如果您扩展列表片段并希望在列表视图为空时设置图像视图。 android提供设置空视图方法，用于在列表视图没有可用数据时显示视图。见下文如何设置空视图。

下面是我的列表片段的布局布局内容当列表视图没有内容显示时将显示的图像视图的空布局。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>

在你的java代码中打开你的列表片段，在你的片段中添加下面的行。

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