我的listview有问题，它适用于模拟器但不适用于真实设备。我测试了2个真实的设备，但没有填充。我使用json从数据库获取listview数据。 Json结果没问题，因为它打印到logcat并在模拟器上填充listview。
ListView Java：
public class ActivityRequestsFrom extends MainActivity implements AdapterView.OnItemClickListener {
______________________________________________________________________________
Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_requests_from);
lv = (ListView) findViewById(R.id.listRequests);
RequestsAdapter adapter = new RequestsAdapter(this, arrRequest_Name, arrRequest_Number,
arrRequest_Username, arrRequest_Result, imageId);
lv.setAdapter(adapter);
lv.setOnItemClickListener(this);
}
______________________________________________________________________________
class RequestsAdapter extends ArrayAdapter<String>
{
Context context;
List<String> Request_Name;
List<String> Request_Number;
List<String> Request_Username;
List<String> Request_Result;
Integer[] imgid;
RequestsAdapter(Context c, List<String> Request_Name,
List<String> Request_Number, List<String> Request_Username,
List<String> Request_Result, Integer[] imgid)
{
super(c, R.layout.activity_requests_single, R.id.textName, Request_Name);
this.context=c;
this.Request_Name=Request_Name;
this.Request_Number=Request_Number;
this.Request_Username=Request_Username;
this.Request_Result=Request_Result;
this.imgid=imgid;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View row=convertView;
if(row==null)
{
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(R.layout.activity_requests_single, parent, false); }
TextView txtName = (TextView) row.findViewById(R.id.textName);
TextView txtNumber = (TextView) row.findViewById(R.id.textNumber);
TextView txtUsername = (TextView) row.findViewById(R.id.textUsername);
TextView txtResult = (TextView) row.findViewById(R.id.textResult);
ImageView imageView = (ImageView) row.findViewById(R.id.imageView);
Map<String, Integer> drawableMap = new HashMap<String, Integer>();
drawableMap.put("ok",R.drawable.request_pending_from);
drawableMap.put("pending",R.drawable.request_pending_from);
drawableMap.put("rejected",R.drawable.request_rejected_from);
drawableMap.put("blocked",R.drawable.request_blocked_from);
txtName.setText(Request_Name.get(position));
txtNumber.setText(Request_Number.get(position));
txtUsername.setText(Request_Username.get(position));
txtResult.setText(Request_Result.get(position));
//imageView.setImageResource(imgid[position]);
imageView.setImageResource(drawableMap.get(Request_Result.get(position).toLowerCase()));
return row;
}
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// TODO Auto-generated method stub
TextView tvUsername = (TextView) view.findViewById(R.id.textUsername);
usernameSelected = tvUsername.getText().toString();
TextView tvResult = (TextView) view.findViewById(R.id.textResult);
resultSelected = tvResult.getText().toString();
if (resultSelected.equals("Pending"))
{
pendingOptions();
}
else if (resultSelected.equals("Rejected"))
{
rejectedOptions();
}
else if (resultSelected.equals("Blocked"))
{
blockedOptions();
}
else
{
}
}
ListView布局：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<ListView
android:id="@+id/listRequest"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
</ListView>
ListView单一布局
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<TextView
android:id="@+id/textName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/LLdummy"
android:text="Name"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textStyle="italic"
android:layout_marginLeft="10dp"
/>
<TextView
android:id="@+id/textUsername"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textNumber"
android:layout_alignParentRight="true"
android:layout_below="@+id/textNumber"
android:text="Username"
android:textAppearance="?android:attr/textAppearanceSmall" />
<TextView
android:id="@+id/textNumber"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textName"
android:layout_below="@+id/textName"
android:text="Number"
android:textAppearance="?android:attr/textAppearanceSmall"
android:textStyle="bold" />
<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/LLdummy"
android:layout_centerVertical="true"
android:src="@drawable/request_pending_to" />
的Json
private class JsonReadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
HttpResponse response = httpclient.execute(httppost);
jsonResult = inputStreamToString(response.getEntity().getContent()).toString();
}
catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
private StringBuilder inputStreamToString(InputStream is) {
String rLine = "";
StringBuilder answer = new StringBuilder();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((rLine = rd.readLine()) != null) {
answer.append(rLine);
}
}
catch (IOException e) {
// e.printStackTrace();
Toast.makeText(getApplicationContext(),"Error..." + e.toString(), Toast.LENGTH_LONG).show();
}
return answer;
}
@Override
protected void onPostExecute(String result) {
try{
ListDrwaer(); //has ConnectionException (when it cannot reach server)
}catch (Exception e){
Toast.makeText(getApplicationContext(), "Please check your connection..", Toast.LENGTH_LONG).show();
}
}
}// end async task
public void accessWebService() {
JsonReadTask task = new JsonReadTask();
// passes values for the urls string array
task.execute(new String[] { "http://server/file.php?pIMEI="+IMEI });
}
// build hash set for list view
public void ListDrwaer() {
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("request_info");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
String request_name = jsonChildNode.optString("Request_Name");
String request_number = jsonChildNode.optString("Request_Number");
String request_username = jsonChildNode.optString("Request_Username");
String request_result = jsonChildNode.optString("Request_Result");
arrRequest_Name.add(request_name);
arrRequest_Number.add(request_number);
arrRequest_Username.add(request_username);
arrRequest_Result.add(request_result);
System.out.println("Request_Name: "+request_name);
System.out.println("Request_Number: "+request_number);
System.out.println("Request_Username: "+request_username);
System.out.println("Request_Result: "+request_result);
}
} catch (JSONException e) {
System.out.println("Json Error Requests" +e.toString());
Toast.makeText(getApplicationContext(), "No Requests Pending", Toast.LENGTH_SHORT).show();
}
}
调用异步
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_requests_from);
...
accessWebService();
//ListView
lv = (ListView) findViewById(R.id.listRequests);
RequestsAdapter adapter = new RequestsAdapter(this, arrRequest_Name, arrRequest_Number, arrRequest_Username, arrRequest_Result, imageId);
lv.setAdapter(adapter);
lv.setOnItemClickListener(this);
答案 0 :(得分：2)
此处的问题是，Adapter上设置ListView时未收到数据。这是因为数据填充在AysncTask中，其本质上是 async hronous。这意味着它将在后台运行而另一个代码运行（即ListView填充。
因此，在onPostExecute()中，您需要使用notifyDataSetChanged()让ListView知道要填充新项目。
@Override
protected void onPostExecute(String result) {
// your code
adapter.notifyDataSetChanged(); // this line here
}// end async task
在您的示例中，这显然会要求您将Adapter作为成员变量或将其传递给AsyncTask。