Question

在我的Android应用程序中，我试图在列表视图中显示我的数据库表的内容，它正在完美地工作..并提供这样的输出，

enter image description here

这是我通过表格调用所有名称的方法，

public void getAllPartiesName()
{
    try
    {
        db=new DBAdapter(PartyNamesActivity.this);
        db.open();
        c=db.getAllPartiesName();
        partiesnamelist=new ArrayList<String>();
        if(c.getCount()>0)
        {                                
            if (c.moveToFirst())
            {
                do
                {
                    partiesnamelist.add(c.getString(0));
                } 
                while (c.moveToNext());
            }

        }
        else
        {
            Toast toast=Toast.makeText(getBaseContext(), "No Names Found!", Toast.LENGTH_LONG);
            toast.setGravity(Gravity.CENTER, 0, 0);
            toast.show();
        }
        c.close();
        db.close();
    }
    catch(Exception e)
    {
        Toast.makeText(getApplicationContext(), "Exception: "+e.getMessage(), Toast.LENGTH_LONG).show();
    }

    ArrayAdapter<String> adapter=new ArrayAdapter<String>(PartyNamesActivity.this,android.R.layout.simple_list_item_1,partiesnamelist);
    lvpartiesname.setAdapter(adapter);
}

但是当我尝试向ListView添加自定义布局时，它给出错误，实际上我想在左侧显示每个列表视图名称的图像... 所以，我使用了自定义布局..

自定义布局就是这个，

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="@drawable/list_selector"
android:orientation="horizontal"
android:padding="5dip" >

<!--  ListRow Left sied Thumbnail image -->
<LinearLayout android:id="@+id/thumbnail"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:padding="3dip"
    android:layout_alignParentLeft="true"
    android:background="@drawable/image_bg"
    android:layout_marginRight="5dip">

    <ImageView
        android:id="@+id/list_image"
        android:layout_width="50dip"
        android:layout_height="50dip"
        android:src="@drawable/ic_launcher"/>

</LinearLayout>

<!-- Text of List-->
<TextView
    android:id="@+id/tv"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@+id/thumbnail"
    android:layout_toRightOf="@+id/thumbnail"
    android:text="List View Name"
    android:textColor="#040404"
    android:typeface="sans"
    android:textSize="15dip"
    android:textStyle="bold"/>

</RelativeLayout>

添加此布局后，我更改了Array Adapter的代码，

ArrayAdapter<String> adapter=new ArrayAdapter<String>(PartyNamesActivity.this,R.layout.list_row,partiesnamelist);
lvpartiesname.setAdapter(adapter);

这里我遇到了问题，（给出了这个错误）

我的LogCat，

11-01 10:01:43.624: E/AndroidRuntime(10968): FATAL EXCEPTION: main
11-01 10:01:43.624: E/AndroidRuntime(10968): java.lang.IllegalStateException: ArrayAdapter requires the resource ID to be a TextView
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:386)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.AbsListView.obtainView(AbsListView.java:2159)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at    android.widget.ListView.measureHeightOfChildren(ListView.java:1246)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.ListView.onMeasure(ListView.java:1158)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.View.measure(View.java:15518)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.View.measure(View.java:15518)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.View.measure(View.java:15518)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.View.measure(View.java:15518)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.View.measure(View.java:15518)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.Choreographer.doCallbacks(Choreographer.java:562)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.Choreographer.doFrame(Choreographer.java:532)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.os.Handler.handleCallback(Handler.java:725)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.os.Handler.dispatchMessage(Handler.java:92)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.os.Looper.loop(Looper.java:137)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.app.ActivityThread.main(ActivityThread.java:5041)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at java.lang.reflect.Method.invokeNative(Native Method)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at java.lang.reflect.Method.invoke(Method.java:511)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
11-01 10:01:43.624: E/AndroidRuntime(10968):    at dalvik.system.NativeStart.main(Native Method)
11-01 10:01:43.624: E/AndroidRuntime(10968): Caused by: java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to android.widget.TextView
11-01 10:01:43.624: E/AndroidRuntime(10968):    at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:379)

请帮助我，

感谢。

Answer 1

创建自定义适配器。 CutomAdapter扩展了ArrayAdapter。在getView中，您会自动展开自定义布局并返回视图。使用ViewHolder模式实现平滑滚动和性能。

http://developer.android.com/training/improving-layouts/smooth-scrolling.html

将活动上下文和arraylist传递给自定义适配器的构造函数，并在那里使用它。

public class CustomAdapter extends ArrayAdapter<String>
{

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return names.size();
    }
    LayoutInflater inflater;
    ArrayList<String> naems;
    public CustomAdapter(Context context, ArrayList<String> partiesnamelist) {
        super(context, 0);
        // TODO Auto-generated constructor stub
        inflater = LayoutInflater.from(context);
        names= partiesnamelist;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        ViewHolder holder;
        if(convertView==null)
        {
        convertView = inflater.inflate(R.layout.list_item, parent,false);
            // inflate layout 
        holder = new ViewHolder();
        holder.tv = (TextView) convertView.findViewById(R.id.textView1);
        // use the view object to initialize views
        holder.iv = (ImageView) convertView.findViewById(R.id.list_image);
        convertView.setTag(holder); 
    } else { 
        holder = (ViewHolder) convertView.getTag(); 
    } 
        holder.tv.setText(names.get(position)); 
            // set text to textview usinf position adn arraylist names
            // set image to imageview using position
        return convertView;
    }
static class ViewHolder
{
    TextView tv;
    ImageView iv;
}
}

然后在Activtiy

CustomAdapter cus = new CustomAdapter(ActivityName.this,partiesnamelist);
lvpartiesname.setAdapter(cus);

list_item.xml //单个相对布局就足够了

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:padding="5dip" >
<ImageView
        android:id="@+id/list_image"
        android:layout_width="50dip"
        android:layout_height="50dip"
        android:src="@drawable/ic_launcher"/>

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:text="List View Name"
    android:textColor="#040404"
    android:textSize="15dip"
    android:textStyle="bold"
    android:typeface="sans" />

</RelativeLayout>

使用文本在列表视图中添加图像时出错

1 个答案: