这是我通过 php 从 mysql 数据库选择图像和文本的代码。它在 ScrollView 中以线性布局显示。我想做的就是将布局更改为 listview，如 this example. 我尝试了listview和其他很多方法，但它不能正常工作。我是android新手，所以我尝试了很长时间。请帮助我根据我的要求编辑我的代码。拜托。
JAVA
@SuppressLint("NewApi")
public class News_and_events extends Fragment {
private String jsonResult;
private String url = "http://192.168.2.7/crescentnews/select.php";
HttpPost httppost;
StringBuffer buffer;
HttpResponse response;
HttpClient httpclient;
List<NameValuePair> nameValuePairs;
ProgressDialog dialog = null;
ImageView img;
Bitmap bitmap;
ProgressDialog pDialog;
// alert dialog manager
AlertDialogManager alert = new AlertDialogManager();
// Internet detector
ConnectionDetector cd;
InputStream is=null;
String result=null;
String line=null;
int code;
public News_and_events(){}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
pDialog = new ProgressDialog(getActivity());
View rootView = inflater.inflate(R.layout.activity_news_and_events, container, false);
cd = new ConnectionDetector(rootView.getContext());
// Check if Internet present
if (!cd.isConnectingToInternet()) {
// Internet Connection is not present
alert.showAlertDialog(getActivity(),
"Internet Connection Error",
"Please connect to working Internet connection", false);
// stop executing code by return
//return.rootView;
return rootView;
}
accessWebService();
return rootView;
}
// Async Task to access the web
private class JsonReadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
List<NameValuePair> nameValuePair = new ArrayList<NameValuePair>(1);
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
httppost.setEntity(new UrlEncodedFormEntity(nameValuePair));
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(getActivity().getApplicationContext(),
"Error..." + e.toString(), Toast.LENGTH_LONG).show();
}
return answer;
}
@Override
protected void onPostExecute(String result) {
display();
}
}// end async task
public void accessWebService() {
JsonReadTask task = new JsonReadTask();
// passes values for the urls string array
task.execute(new String[] { url });
}
// build hash set for list view
public void display() {
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("news_details");
LinearLayout MainLL= (LinearLayout)getActivity().findViewById(R.id.newslayout);
//LinearLayout headLN=(LinearLayout)findViewById(R.id.headsection);
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
final String head = jsonChildNode.optString("title");
final String details = jsonChildNode.optString("text");
final String date = jsonChildNode.optString("date");
final String image = jsonChildNode.optString("img");
//final String time = jsonChildNode.optString("time");
//img = new ImageView(this.getActivity());
//new LoadImage().execute("http://192.168.2.7/crescentnews/images/"+image);
img = new ImageView(this.getActivity());
// Toast.makeText(getActivity(),image, Toast.LENGTH_LONG).show();
LoadImage ldimg=new LoadImage();
ldimg.setImage(img);
ldimg.execute("http://192.168.2.7/crescentnews/images/"+image);
TextView headln = new TextView(this.getActivity());
headln.setText(head); // News Headlines
headln.setTextSize(16);
headln.setTextColor(Color.BLACK);
headln.setGravity(Gravity.CENTER);
headln.setBackgroundColor(Color.parseColor("#ffcd14"));
// headln.setBackgroundResource(R.drawable.menubg);
headln.setPadding(0, 20, 0, 0);
// headln.setHeight(50);
headln.setClickable(true);
TextView dateln = new TextView(this.getActivity());
dateln.setText(date); // News Headlines
dateln.setTextSize(12);
dateln.setTextColor(Color.BLACK);
dateln.setGravity(Gravity.RIGHT);
//dateln.setBackgroundColor(Color.parseColor("#f20056"));
dateln.setBackgroundColor(0x00000000);
dateln.setPadding(0, 0, 10, 10);
dateln.setWidth(100);
dateln.setClickable(true);
View sep=new View(this.getActivity());
sep.setBackgroundColor(Color.parseColor("#252525"));
sep.setMinimumHeight(10);
TextView detailsln = new TextView(this.getActivity());
detailsln.setText(details); // News Details
detailsln.setTextSize(12);
detailsln.setTextColor(Color.BLACK);
detailsln.setGravity(Gravity.CENTER);
detailsln.setPadding(10, 10, 10, 10);
int width = LayoutParams.WRAP_CONTENT;
int height = 200;
LinearLayout.LayoutParams parms = new LinearLayout.LayoutParams(width,height);
img.setLayoutParams(parms);
parms.gravity = Gravity.CENTER;
img.setPaddingRelative (15, 15, 15, 15);
MainLL.addView(headln);
MainLL.addView(dateln);
// MainLL.addView(photo);
MainLL.addView(img);
MainLL.addView(detailsln);
MainLL.addView(sep);
img.setClickable(true);
// img.buildDrawingCache();
// final Bitmap bmap = img.getDrawingCache();
headln.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent(getActivity().getApplicationContext(),InnerNewsAndEvents.class);
intent.putExtra("head",head.toString());
intent.putExtra("details",details.toString());
intent.putExtra("date",date.toString());
intent.putExtra("image", image);
startActivity(intent);
}
});
dateln.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent(getActivity().getApplicationContext(),InnerNewsAndEvents.class);
intent.putExtra("head",head.toString());
intent.putExtra("details",details.toString());
intent.putExtra("date",date.toString());
intent.putExtra("image", image);
startActivity(intent);
}
});
img.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent(getActivity().getApplicationContext(),InnerNewsAndEvents.class);
intent.putExtra("head",head.toString());
intent.putExtra("details",details.toString());
intent.putExtra("date",date.toString());
intent.putExtra("image", image);
startActivity(intent);
}
});
detailsln.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent(getActivity().getApplicationContext(),InnerNewsAndEvents.class);
intent.putExtra("head",head.toString());
intent.putExtra("details",details.toString());
intent.putExtra("date",date.toString());
intent.putExtra("image", image);
startActivity(intent);
}
});
}
} catch (JSONException e) {
Toast.makeText(getActivity().getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
}
private class LoadImage extends AsyncTask<String, String, Bitmap> {
ImageView img;
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog.setMessage("Loading Image ....");
pDialog.show();
}
public void setImage(ImageView img ){
this.img=img;
}
protected Bitmap doInBackground(String... args) {
try {
bitmap = BitmapFactory.decodeStream((InputStream)new URL(args[0]).openStream());
}
catch (Exception e) { e.printStackTrace(); }
return bitmap;
}
protected void onPostExecute(Bitmap image) {
if(image != null){
img.setImageBitmap(image);
pDialog.dismiss();
}
pDialog.dismiss();
}
}
public static boolean isInternetReachable()
{
try {
//make a URL to a known source
URL url = new URL("http://www.google.com");
//open a connection to that source
HttpURLConnection urlConnect = (HttpURLConnection)url.openConnection();
//trying to retrieve data from the source. If there
//is no connection, this line will fail
Object objData = urlConnect.getContent();
} catch (UnknownHostException e) {
e.printStackTrace();
return false;
}
catch (IOException e) {
e.printStackTrace();
return false;
}
return true;
}
}
XML
<ScrollView
android:id="@+id/scrollView1"
android:layout_width="match_parent"[![enter image description here][1]][1]
(来源:codelearn.org)
android:layout_height="wrap_content" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:baselineAligned="false"
>
<LinearLayout
android:id="@+id/newslayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:background="#ffffff"
>
</LinearLayout>
</LinearLayout>
</ScrollView>
</LinearLayout>
最佳答案
您无法从 AsyncTask 中调用 display() 来在 ListView 中显示结果。
您应该按照以下步骤操作
在创建时，调用 AsyncTask 从服务器获取数据并将其填充到数组列表中。当异步任务运行时，请确保显示进度对话框，以便用户无法在 UI 线程中执行任何操作。
在创建时，初始化 ListView 。
在 AsyncTask 执行后，填充数组列表中的所有元素后，调用适配器填充 ListView 。
定义一个扩展 BaseAdapter 的适配器，您可以使用它从数组列表填充 ListView 。
您可能想查看this link类似的工作示例。
关于android - 无法正确地将我的 LinearLayout 更改为 ListView，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27833783/