机器人：getFragmentManager（）返回null [英] android: getFragmentManager() returns null
本文介绍了机器人：getFragmentManager（）返回null的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
编辑：问题是该片段是充分利用活动分离。但是，我不知道如何prevent这一点。
我有一个使用一个标签栏的应用程序。当点击其中一个标签加载主题中的标签栏下方的空间列表。其中一个主题是'路线'。当点击这个空间现在被替换为在顶部（标签栏下方），另一间酒吧，其中包括一个后退按钮和获取路线按钮的布局。下面说酒吧的位置的谷歌地图。如果我点击返回如预期，我回到了名单。然后，如果我点击行车路线列表中的我回到地图预期。然后，如果我再次点击再次回到我到列表中崩溃的应用程序后退来代替。它显示一个指向该行 FragmentTransaction英尺= getFragmentManager（）NullPointerException异常的BeginTransaction（）; 后退按钮的setOnClickListener内。不知道为什么它失去轨道fragmentManager的。
I have an application that uses a tab bar. When one of the tabs is clicked it loads a list of topics in the space below the tab bar. One of the topics is 'Directions'. Upon clicking this the space is now replaced with a layout that has another bar at the top (below the tab bar) that includes a 'Back' button and a 'Get Directions' button. Below that bar is a google map of the location. If I click 'Back' I am returned to the list as expected. Then if I click 'Directions' in the list I go back to the map as expected. Then if I click 'Back' again instead of returning me to the list again it crashes the app. It shows a NullPointerException that points to the line FragmentTransaction ft = getFragmentManager().beginTransaction(); inside the Back Button's setOnClickListener. Not sure why it's losing track of the fragmentManager.
下面是最初加载列表选项卡中的文件：
Here is the file for tab that initially loads the list:
package org.childrensmuseum.visittcmindy;
import java.util.ArrayList;
import android.content.Context;
import android.graphics.drawable.GradientDrawable;
import android.graphics.drawable.GradientDrawable.Orientation;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
public class InfoTab extends Fragment {
private ArrayList<InfoPage> pages;
private TCMSQLiteHelper sqliteHelper;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
sqliteHelper = new TCMSQLiteHelper(this.getActivity());
pages = sqliteHelper.getAllPages();
InfoPage directions = new InfoPage();
directions.setPage_id(101);
directions.setTitle("Directions");
InfoPage calendar = new InfoPage();
calendar.setPage_id(102);
calendar.setTitle("Calendar");
pages.add(1, directions);
pages.add(2, calendar);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.infolist, container, false);
ListView infoList = (ListView)v.findViewById(R.id.infolistview);
int[] colors = {0xFFCFE8FF,0xFFCFE8FF};
infoList.setDivider(new GradientDrawable(Orientation.RIGHT_LEFT, colors));
infoList.setDividerHeight(2);
ArrayList<String> valueList = new ArrayList<String>();
for(InfoPage page : pages){
valueList.add(page.getTitle());
}
String[] values = new String[valueList.size()];
values = valueList.toArray(values);
infoList.setAdapter(new InfoAdapter(getActivity(), values));
infoList.setOnItemClickListener(new OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> parent, View v, int p,
long id) {
long page_id = pages.get(p).getPage_id();
// If Directions
if(page_id==101){
DirectionsView directions = new DirectionsView();
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.realtabcontent, directions);
ft.commit();
} else {
PageDetails details = PageDetails.newInstance(pages.get(p).getPage_id());
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.realtabcontent, details);
ft.commit();
}
}
});
return v;
}
private class InfoAdapter extends ArrayAdapter<String> {
public InfoAdapter(Context context, String[] values) {
super(context, R.layout.explorecell, values);
// TODO Auto-generated constructor stub
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View row = inflater.inflate(R.layout.infocell,parent,false);
InfoPage page = pages.get(position);
if(position % 2 != 0){
row.setBackgroundColor(getResources().getColor(R.color.listblue));
} else {
row.setBackgroundColor(getResources().getColor(R.color.white));
}
String page_icon = "page_" + page.getPage_id();
ImageView iv = (ImageView)row.findViewById(R.id.infoImage);
TextView tv = (TextView)row.findViewById(R.id.infoText);
String title = page.getTitle();
String[] titleParts = title.split("[ ]");
String newTitle = "";
for(int i=0;i<titleParts.length;i++){
titleParts[i] = titleParts[i].substring(0,1).toUpperCase() + titleParts[i].substring(1);
newTitle += titleParts[i];
if(i<titleParts.length-1){
newTitle += " ";
}
}
iv.setImageResource(getActivity().getResources().getIdentifier(page_icon, "drawable","org.childrensmuseum.visittcmindy"));
tv.setText(newTitle);
return row;
}
}
@Override
public void onDestroy() {
super.onDestroy();
if(sqliteHelper != null) {
sqliteHelper.close();
}
}
}
下面是当您单击列表中的该项目被称为DirectionsView文件：
Here is the file for the DirectionsView that is called when you click that item in the list:
package org.childrensmuseum.visittcmindy;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.List;
import android.app.Dialog;
import android.content.Intent;
import android.location.Address;
import android.location.Geocoder;
import android.location.Location;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.util.Log;
import android.view.InflateException;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesClient;
import com.google.android.gms.location.LocationClient;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
public class DirectionsView extends Fragment implements
GooglePlayServicesClient.ConnectionCallbacks,
GooglePlayServicesClient.OnConnectionFailedListener {
private static View v;
private MainApplication main;
private LocationClient mLocationClient;
@Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
main = MainApplication.getInstance();
mLocationClient = new LocationClient(getActivity(), this, this);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if(v != null){
ViewGroup parent = (ViewGroup) v.getParent();
if(parent != null){
parent.removeView(v);
}
}
try {
mLocationClient.connect();
v = inflater.inflate(R.layout.directions, container, false);
GoogleMap mMap;
mMap = ((SupportMapFragment) getFragmentManager().findFragmentById(R.id.directionsmap)).getMap();
Geocoder coder = new Geocoder(getActivity());
List<Address> address;
try {
Log.d("DEBUG","2");
String museumAddress = "The Children's Museum of Indianapolis, 3000 North Meridian St, Indianapolis, IN 46208";
address = coder.getFromLocationName(museumAddress, 1);
Address museumLocation = address.get(0);
mMap.addMarker(new MarkerOptions()
.position(new LatLng(museumLocation.getLatitude(), museumLocation.getLongitude()))
.title(getResources().getString(R.string.museumTitle)));
} catch(Exception e) {
Log.d("DEBUG","Error Adding Marker: "+e.getLocalizedMessage());
}
Button backButton = (Button)v.findViewById(R.id.backtoexhibits);
backButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
FragmentTransaction ft = getFragmentManager().beginTransaction();
InfoTab infoTab = new InfoTab();
ft.replace(R.id.realtabcontent, infoTab);
ft.commit();
}
});
Button directionsButton = (Button)v.findViewById(R.id.getdirections);
directionsButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
try {
openDirectionsDialog();
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
} catch (InflateException e){
/* map is already there, just return view as it is */
e.printStackTrace();
}
return v;
}
@Override
public void onConnectionFailed(ConnectionResult result) {
// TODO Auto-generated method stub
}
@Override
public void onConnected(Bundle connectionHint) {
// TODO Auto-generated method stub
}
@Override
public void onDisconnected() {
// TODO Auto-generated method stub
}
private void openDirectionsDialog() throws UnsupportedEncodingException{
final Dialog dialog = new Dialog(getActivity());
dialog.setContentView(R.layout.getdirections);
dialog.setTitle("Get Directions");
Button useAddressBtn = (Button)dialog.findViewById(R.id.useAddress);
Button useLocationBtn = (Button)dialog.findViewById(R.id.useLocationBtn);
final EditText addressText = (EditText)dialog.findViewById(R.id.addressText);
final String museumAddress = URLEncoder.encode("The Children's Museum of Indianapolis, 3000 North Meridian St, Indianapolis, IN 46208","UTF-8");
useAddressBtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String address;
try {
address = URLEncoder.encode(addressText.getText().toString(),"UTF-8");
String url = "http://maps.google.com/maps?saddr="+address+"&daddr="+museumAddress;
Intent intent = new Intent(android.content.Intent.ACTION_VIEW, Uri.parse(url));
intent.setClassName("com.google.android.apps.maps", "com.google.android.maps.MapsActivity");
startActivity(intent);
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
useLocationBtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Location mCurrentLocation = mLocationClient.getLastLocation();
double lat = mCurrentLocation.getLatitude();
double lng = mCurrentLocation.getLongitude();
String url = "http://maps.google.com/maps?saddr="+lat+","+lng+"&daddr="+museumAddress;
Intent intent = new Intent(android.content.Intent.ACTION_VIEW, Uri.parse(url));
intent.setClassName("com.google.android.apps.maps", "com.google.android.maps.MapsActivity");
startActivity(intent);
}
});
dialog.show();
}
}
修改
下面是堆栈跟踪
12-11 14:07:03.547: E/AndroidRuntime(1846): FATAL EXCEPTION: main
12-11 14:07:03.547: E/AndroidRuntime(1846): Process: org.childrensmuseum.visittcmindy, PID: 1846
12-11 14:07:03.547: E/AndroidRuntime(1846): java.lang.NullPointerException
12-11 14:07:03.547: E/AndroidRuntime(1846): at org.childrensmuseum.visittcmindy.DirectionsView$1.onClick(DirectionsView.java:80)
12-11 14:07:03.547: E/AndroidRuntime(1846): at android.view.View.performClick(View.java:4424)
12-11 14:07:03.547: E/AndroidRuntime(1846): at android.view.View$PerformClick.run(View.java:18383)
12-11 14:07:03.547: E/AndroidRuntime(1846): at android.os.Handler.handleCallback(Handler.java:733)
12-11 14:07:03.547: E/AndroidRuntime(1846): at android.os.Handler.dispatchMessage(Handler.java:95)
12-11 14:07:03.547: E/AndroidRuntime(1846): at android.os.Looper.loop(Looper.java:137)
12-11 14:07:03.547: E/AndroidRuntime(1846): at android.app.ActivityThread.main(ActivityThread.java:4998)
12-11 14:07:03.547: E/AndroidRuntime(1846): at java.lang.reflect.Method.invokeNative(Native Method)
12-11 14:07:03.547: E/AndroidRuntime(1846): at java.lang.reflect.Method.invoke(Method.java:515)
12-11 14:07:03.547: E/AndroidRuntime(1846): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
12-11 14:07:03.547: E/AndroidRuntime(1846): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
12-11 14:07:03.547: E/AndroidRuntime(1846): at dalvik.system.NativeStart.main(Native Method)
修改2：
每建议，我试图取代
Edit 2:
Per suggestions, I tried replacing
FragmentTransaction ft = getFragmentManager().beginTransaction();
与
FragmentTransaction ft = getActivity().getSupportFragmentManager().beginTransaction();
有错误没有发生变化。
There was no change in the error.
推荐答案
我建议这样的：的 http://developer.android.com/training/implementing-navigation/lateral.html
这是对使用viewPager和fragmentPagerAdapter导航选项卡，让您不必手动设置一个onClickListener更改片段，做一个教程。这应该被分开prevent片段。
It's a tutorial on using a viewPager and fragmentPagerAdapter with navigation tabs, so that you don't have to manually set up an onClickListener to change fragments. This should prevent fragments from being detached.
这篇关于机器人：getFragmentManager（）返回null的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
