我在主活动中有一个自定义的BaseAdapter和一个add按钮。该按钮打开一个带有文本框的对话框,您可以通过这种方式向列表添加新元素。问题是这个列表不能刷新。在onActivityResult()函数中,我打印列表中的元素数量,每次在对话框中单击OK时,数量都会增加,因此我知道这只是刷新不起作用。我的BaseAdapter和我的activity:
class ListaOrase extends BaseAdapter{
private Activity context;
ArrayList<String> orase;
public ListaOrase(Activity context){
this.context=context;
orase=new ArrayList<String>();
}
public void add(String string){
orase.add(string);
this.notifyDataSetChanged();
}
public View getView (int position, View convertView, ViewGroup list) {
View element;
if (convertView == null)
{
LayoutInflater inflater = context.getLayoutInflater();
element = inflater.inflate(R.layout.lista, null);
}
else element = convertView;
TextView elementLista=(TextView)element.findViewById(R.id.elementLista);
elementLista.setText(orase.get(position));
return element;
}
}
public class WeatherAppActivity extends ListActivity {
Button buton;
ListaOrase lista;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
lista=new ListaOrase(this);
buton=(Button)findViewById(R.id.buton);
lista.add("Bucuresti");
lista.add("Sibiu");
setListAdapter(lista);
}
public void add(View view){
Intent intent=new Intent();
intent.setClass(this, Adauga.class);
startActivityForResult(intent, 0);
}
public void onActivityResult (int requestCode, int responseCode, Intent data){
System.out.println("Apelata");
if(responseCode==1){
lista.add(data.getStringExtra("oras")); // e chiar getText()
System.out.println(lista.getCount());
lista.notifyDataSetChanged();
}
}
}
正如你所看到的,我试图刷新(notifyDataSetChanged();)当添加一个新元素(在BaseAdapter扩展类)和方法onActivityResult,在对话框传递新元素到主活动后。我重复一遍,元素被添加到列表中是因为计数增加了,它只是没有刷新。
谢谢你的回答!
它不刷新是正常的,你将一个项目添加到"lista"但是适配器保留了它自己的列表副本,所以或者你在适配器中再次设置列表然后调用notifydatachchanged或者你将新项目添加到适配器
无论如何,我看到了一些奇怪的事情,我认为你可以使用数组适配器简化一切,你不需要实现添加,等等。我写了一些代码来简化你的代码:
public class WeatherAppActivity extends ListActivity {
Button buton;
ItemsAdapter lista;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
List<String> initialList = new ArrayList<String>();
initialList.add("Bucuresti");
initialList.add("Sibiu");
lista=new ItemsAdapter(this, initialList);
buton=(Button)findViewById(R.id.button1);
buton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
lista.add(""+System.currentTimeMillis()); // e chiar getText()
lista.notifyDataSetChanged();
}
});
setListAdapter(lista);
}
class ItemsAdapter extends ArrayAdapter<String> {
public ItemsAdapter(Context context, List<String> list) {
super(context, R.layout.lista, list);
}
@Override
public View getView(final int position, View row, final ViewGroup parent) {
final String item = getItem(position);
ItemWrapper wrapper = null;
if (row == null) {
row = getLayoutInflater().inflate(R.layout.lista, parent, false);
wrapper = new ItemWrapper(row);
row.setTag(wrapper);
} else {
wrapper = (ItemWrapper) row.getTag();
}
wrapper.refreshData(item);
return row;
}
class ItemWrapper {
TextView text;
public ItemWrapper(View row) {
text = (TextView) row.findViewById(R.id.elementLista);
}
public void refreshData(String item) {
text.setText(item);
}
}
}
}
这些是我使用的xml:
main。xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="63dp"
android:text="Button" />
<ListView
android:id="@id/android:list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" >
</ListView>
</RelativeLayout>
lista.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/elementLista"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium" />
</LinearLayout>
这是使用baseadapter的适配器版本:
class ItemsBaseAdapter extends BaseAdapter {
private List<String> items;
private Context mContext;
public ItemsBaseAdapter(Context context, List<String> list) {
items = list;
mContext = context;
}
public void addItem(String str) {
items.add(str);
}
@Override
public View getView(final int position, View row, final ViewGroup parent) {
final String item = (String) getItem(position);
ItemWrapper wrapper = null;
if (row == null) {
row = getLayoutInflater().inflate(R.layout.lista, parent, false);
wrapper = new ItemWrapper(row);
row.setTag(wrapper);
} else {
wrapper = (ItemWrapper) row.getTag();
}
wrapper.refreshData(item);
return row;
}
class ItemWrapper {
TextView text;
public ItemWrapper(View row) {
text = (TextView) row.findViewById(R.id.elementLista);
}
public void refreshData(String item) {
text.setText(item);
}
}
@Override
public int getCount() {
return items.size();
}
@Override
public Object getItem(int position) {
return items.get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
}
这是列表项的版本,左边也包括一个imageview:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<ImageView
android:layout_height="wrap_content"
android:src="@android:drawable/btn_star_big_on"
android:scaleType="fitCenter"
android:layout_width="wrap_content"
/>
<TextView
android:id="@+id/elementLista"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium"
/>
</LinearLayout>