编辑: 以下问题出现在我的 Samsung Galaxy S3 上，但是，当我在我的 Sony Xperia Z3+ 上运行相同的应用程序时，它根本不显示 WIFI 列表。 :-/
我的应用出现了奇怪的情况。我目前有五个不同的 fragment 。所有这些都按预期工作 FragmentTransaction除了一个。
最初，当我启动我的应用程序时，我使用了一个 Android Studio 模板，但这似乎太过分了，因为它使用了 Fragments。而不是 ListView用于列出我的 WIFI 项目。我已经有一段时间没有使用 Android 开发任何东西了，所以我正在努力追赶。
我将代码留在原地并继续开发界面。当我最终决定删除用 Fragment 填充主容器的代码时，问题就来了。 “项目”并将其替换为 Fragment包含 ListView .
我所有的Fragments当我从菜单中选择新项目时按预期工作并按预期替换，但这个新的 ListView Fragment 除外。 ，一旦我选择它，它就会保留在后台。
我选择之后，如果我选择其他Fragments它们按应有的方式更改，但第一个保留在原位。
我发现最接近我的情况的问题是 this one ，但这对我没有帮助。
这是选择问题后我的屏幕的样子 Fragment和另一个 Fragment :
我的 MainActivity onCreate()方法:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
setupWifiScan();
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Scanning for devices...", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
scanForNetworks(view);
}
});
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
if(findViewById(R.id.fragment_container) != null){
if(savedInstanceState != null){
return;
}
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
WifiFragment wifiFragment = new WifiFragment();
wifiFragment.setArguments(getIntent().getExtras());
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.fragment_container, wifiFragment);
transaction.commit();
}else{
Log.i("MAIN_ACTIVITY", "fragment_container is NULL");
}
}
我的 MainActivity onNavigationItemSelected()方法:
@覆盖 公共(public) bool onNavigationItemSelected(菜单项){ //处理导航 View 项点击这里。 int id = item.getItemId();
if (id == R.id.nav_settings) {
GeneralSettings generalSettings = new GeneralSettings();
Bundle args = new Bundle();
args.putInt(GeneralSettings.ARG_POSITON, 0);
generalSettings.setArguments(args);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.fragment_container, generalSettings);
transaction.addToBackStack(null);
int stackId = transaction.commit();
Log.i(this.getClass().getSimpleName(), "Stack ID: " + stackId);
}else if(id == R.id.nav_wlan_setting){
WifiSettings wifiSettings = new WifiSettings();
Bundle args = new Bundle();
args.putInt(GeneralSettings.ARG_POSITON, 0);
wifiSettings.setArguments(args);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.fragment_container, wifiSettings);
transaction.addToBackStack(null);
int stackId = transaction.commit();
Log.i(this.getClass().getSimpleName(), "Stack ID: " + stackId);
}else if(id == R.id.nav_led_settings){
UvLedSettings uvLedSettings = new UvLedSettings();
Bundle args = new Bundle();
args.putInt(GeneralSettings.ARG_POSITON,0);
uvLedSettings.setArguments(args);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.fragment_container, uvLedSettings);
transaction.addToBackStack(null);
int stackId = transaction.commit();
Log.i(this.getClass().getSimpleName(), "Stack ID: " + stackId);
}else if(id == R.id.nav_server_settings){
ServerSettings serverSettings = new ServerSettings();
Bundle args = new Bundle();
// TODO: Fix Args Settings for all Fragments
args.putInt(GeneralSettings.ARG_POSITON, 0);
serverSettings.setArguments(args);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.fragment_container, serverSettings);
transaction.addToBackStack(null);
int stackId = transaction.commit();
Log.i(this.getClass().getSimpleName(), "Stack ID: " + stackId);
} else if (id == R.id.nav_current_device) {
} else if (id == R.id.nav_available_devices){
WifiFragment wifi = new WifiFragment();
Bundle args = new Bundle();
args.putInt(GeneralSettings.ARG_POSITON, 0);
wifi.setArguments(args);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.fragment_container, wifi);
transaction.addToBackStack(null);
int stackId = transaction.commit();
Log.i(this.getClass().getSimpleName(), "Stack ID: " + stackId);
}
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
问题Fragment :
package com.myapp.serviceapplication.fragments;
import android.content.Context;
import android.net.wifi.ScanResult;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import android.widget.RelativeLayout;
import com.myapp.serviceapplication.R;
import com.myapp.serviceapplication.adapters.WifiItemListAdapter;
import java.util.ArrayList;
/**
* A fragment representing a list of Items.
* <p>
* Activities containing this fragment MUST implement the {@link OnListFragmentInteractionListener}
* interface.
*/
public class WifiFragment extends Fragment {
// TODO: Customize parameter argument names
private static final String ARG_COLUMN_COUNT = "column-count";
// TODO: Customize parameters
private int mColumnCount = 1;
private OnListFragmentInteractionListener mListener;
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public WifiFragment() {
// Required empty public constructor
}
// TODO: Customize parameter initialization
@SuppressWarnings("unused")
public static WifiFragment newInstance(int columnCount) {
WifiFragment fragment = new WifiFragment();
Bundle args = new Bundle();
args.putInt(ARG_COLUMN_COUNT, columnCount);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mColumnCount = getArguments().getInt(ARG_COLUMN_COUNT);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_wifi_list, container, false);
if(view instanceof RelativeLayout){
Context context = view.getContext();
RelativeLayout relativeLayout = (RelativeLayout) view;
ListView listView = (ListView) relativeLayout.findViewById(R.id.lst_wifi_items);
listView.setAdapter(new WifiItemListAdapter(this.getContext(), new ArrayList<ScanResult>()));
}
return view;
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
// TODO: This needs to be modified to the correct listener type
if (context instanceof OnListFragmentInteractionListener) {
mListener = (OnListFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnListFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnListFragmentInteractionListener {
// TODO: Update argument type and name
void onListFragmentInteraction(View item);
}
}
问题Fragment布局文件:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".fragments.WifiFragment"
>
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/lst_wifi_items"
android:background="#ffffff"/>
</RelativeLayout>
content_main.xml :
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context=".activities.MainActivity"
tools:showIn="@layout/app_bar_main">
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
activity_main.xml :
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="@layout/app_bar_main"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_main"
app:menu="@menu/activity_main_drawer" />
</android.support.v4.widget.DrawerLayout>
我花了太多时间试图解决这个问题，但我就是看不到问题所在。
最佳答案
发生这种情况是因为您的 fragment 容器位于 ListView 之上，默认情况下，如果您不在 ViewGroup(LinearLayout, RelativeLayout,...) 中使用背景，那么它将是透明的，因此，您需要做的就是将背景放入你的 fragment 容器:
fragment_wifi_list.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".fragments.WifiFragment"
android:background="#ffffff"
>
...
提示:
android:clickable="true"
这样就避免了并发点击问题
关于android - Fragment.replace 不会删除一个 fragment ，而是与多个其他 fragment 一起使用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38457844/