我是Android开发的新手,当我在ListFragment中单击listview中的项目时,我遇到设置进入下一个活动的问题。
当我编译并运行应用程序时,它崩溃并出现错误:尚未创建内容视图。这是相关的代码。任何帮助将非常感激!
MainActivity:
package com.example.szen95.meddict;
import android.app.SearchManager;
import android.content.Context;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.SearchView;
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new SearchFragment())
.commit();
}
getSupportActionBar().setElevation(0f);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
SearchManager searchManager = (SearchManager) getSystemService( Context.SEARCH_SERVICE );
SearchView searchView = (SearchView) menu.findItem( R.id.search_bar ).getActionView();
searchView.setSearchableInfo( searchManager.getSearchableInfo( getComponentName() ) );
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
return super.onOptionsItemSelected(item);
}
}
SearchFragment:
package com.example.szen95.meddict;
/**
* Created by szen95 on 6/15/15.
*/
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
/**
* A placeholder fragment containing a simple view.
*/
public class SearchFragment extends ListFragment {
private ProgressDialog pDialog;
// URL to get contacts JSON
private static String url = "http://dailymed.nlm.nih.gov/dailymed/services/v2/drugclasses.json";
// JSON Node names
private static final String TAG_DATA = "data";
private static final String TAG_CODE = "code";
private static final String TAG_CODING_SYSTEM = "codingSystem";
private static final String TAG_TYPE = "type";
private static final String TAG_NAME = "name";
// contacts JSONArray
JSONArray data = null;
// ArrayAdapter<String> mConditionsAdapter;
public SearchFragment() {
}
ArrayList<HashMap<String, String>> dataList;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
dataList = new ArrayList<HashMap<String, String>>();
// Creating view correspoding to the fragment
View v = inflater.inflate(R.layout.fragment_main, container, false);
ListView lv = getListView();
// Listview on item click listener
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String code = ((TextView) view.findViewById(R.id.code))
.getText().toString();
// Starting single contact activity
Intent in = new Intent(getActivity().getApplicationContext(),
Details.class);
in.putExtra(TAG_NAME, name);
in.putExtra(TAG_CODE, code);
startActivity(in);
}
});
new GetData().execute();
return v;
}
/**
* Async task class to get json by making HTTP call
* */
private class GetData extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(getActivity());
//
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
data = jsonObj.getJSONArray(TAG_DATA);
// looping through All Contacts
for (int i = 0; i < data.length(); i++) {
JSONObject c = data.getJSONObject(i);
String code = c.getString(TAG_CODE);
String codingSystem = c.getString(TAG_CODING_SYSTEM);
String type = c.getString(TAG_TYPE);
String name = c.getString(TAG_NAME);
// tmp hashmap for single contact
HashMap<String, String> data = new HashMap<String, String>();
// adding each child node to HashMap key => value
data.put(TAG_CODE, code);
data.put(TAG_CODING_SYSTEM, codingSystem);
data.put(TAG_TYPE, type);
data.put(TAG_NAME, name);
// adding contact to contact list
dataList.add(data);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
SimpleAdapter adapter = new SimpleAdapter(getActivity(), dataList,
R.layout.list_item_search, new String[] { TAG_NAME, TAG_CODE}, new int[] { R.id.name,
R.id.code});
setListAdapter(adapter);
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
//
// @Override
// public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
// inflater.inflate(R.menu.menu_main, menu);
//
//
// }
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_about) {
// FetchDataTask defTask = new FetchDataTask();
// defTask.execute();
return true;
}
return super.onOptionsItemSelected(item);
}
}
详细信息:
package com.example.szen95.meddict;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.widget.TextView;
public class Details extends ActionBarActivity {
// JSON node keys
private static final String TAG_NAME = "name";
private static final String TAG_CODE = "code";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details);
// getting intent data
Intent in = getIntent();
// Get JSON values from previous intent
String name = in.getStringExtra(TAG_NAME);
String code = in.getStringExtra(TAG_CODE);
// Displaying all values on the screen
TextView lblName = (TextView) findViewById(R.id.name_label);
TextView lblCode = (TextView) findViewById(R.id.code_label);
lblName.setText(name);
lblCode.setText(code);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
return onCreateOptionsMenu(menu);
}
}
答案 0 :(得分:1)
SearchFragment扩展了ListFragment。在ListFragment中,无法在onCreateView()
中调用onCreateView()
,因为getListView()
正在创建片段的内容视图,但尚未完成。 SearchFragment中对getListView()
的调用是异常的原因。
将对onCreateView()
的调用与代码相关的调用移至onViewCreated()
之后调用的片段生命周期方法之一,例如onActivityCreate()
或@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
ListView lv = getListView();
// Listview on item click listener
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String code = ((TextView) view.findViewById(R.id.code))
.getText().toString();
// Starting single contact activity
Intent in = new Intent(getActivity().getApplicationContext(),
Details.class);
in.putExtra(TAG_NAME, name);
in.putExtra(TAG_CODE, code);
startActivity(in);
}
});
}
。例如:
{{1}}