麻烦ViewPager显示片段 [英] Trouble with ViewPager displaying Fragments
问题描述
我想获得一个片段包含三个选项卡使用ViewPager显示。起初我用来实例使用FragmentMgr活动的片段，这工作得很好。当我转换使用ViewPager这个导航，这个片段将不再显示。
I am trying to get a fragment with three tabs displayed using ViewPager. Initially I used to instantiate the fragment from the Activity using FragmentMgr, this worked fine. When I converted this navigation using ViewPager, this Fragment is no longer displayed.
MainActivity.java
MainActivity.java
当我启动片段这样，它就会显示出来。例如：
When I initiate Fragment like this, it gets displayed. eg:
LaunchListFragment fragment = new LaunchListFragment();
fragment.newInstance(LIST_TYPE);
getSupportFragmentManager().beginTransaction()
.add(R.id.item_detail_container,
fragment).commit();
我尝试了上述code这一变化充分利用ViewPager如下：
I tried this change above code to make use of ViewPager as follows:
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(new LaunchPageAdapter(getSupportFragmentManager(),LIST_TYPE));
mViewPager.setCurrentItem(0);
在这里呼吁LaunchPageAdapter LaunchListFragment。
where LaunchPageAdapter calls LaunchListFragment.
LaunchPageAdapter.java
LaunchPageAdapter.java
public class LaunchPageAdapter extends FragmentPagerAdapter {
private static String select="";
public LaunchPageAdapter(FragmentManager fm, String type) {
super(fm);
select=type;
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return LaunchListFragment.newInstance(select);
case 1:
return AddTeamFragment.newInstance();
}
return null;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return 2;
}
下面是LaunchListFragment.java
Here is LaunchListFragment.java
public class LaunchListFragment extends ListFragment implements ActionBar.TabListener {
public static String LIST_TYPE = "invalid";
GenericListData g_data[] = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View result = inflater.inflate(R.layout.fragment_launch_list,
container, false);
setActionTabs();
setList();
return (result);
}
public static Fragment newInstance(String type) {
Fragment frag = new LaunchListFragment();
Bundle args = new Bundle();
LIST_TYPE=type;
args.putString(LIST_TYPE, type);
frag.setArguments(args);
return (frag);
}
这是MainActivity使用main.xml中的布局
This is main.xml layout used by MainActivity
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools= "match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="16dp"
android:layout_marginRight="16dp"
android:baselineAligned="false"
android:divider="?android:attr/dividerHorizontal"
android:orientation="horizontal"
android:showDividers="middle"
tools:context=".MainActivity" >
<fragment
android:id="@+id/item_list"
android:name="com.teammanager.ItemListFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
tools:layout="@android:layout/list_content" />
<FrameLayout
android:id="@+id/item_detail_container"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="3" >
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
</FrameLayout>
由LaunchListFragment使用fragment_launch_list.xml
fragment_launch_list.xml used by LaunchListFragment
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical" >
<ListView
android:id="@android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:drawSelectorOnTop="false" >
</ListView>
<TextView
android:id="@+id/itemName"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_alignParentTop="true"
android:layout_marginBottom="5dp"
android:layout_marginTop="5dp"
android:gravity="center_vertical"
android:textColor="#000000"
android:textSize="22dp"
android:textStyle="bold" />
当我调试这个，我可以看到LaunchListFragment是越来越实例化，以及的onCreate观的onCreate被调用，它只是将不会被显示出来。 （
When I debug this, I can see LaunchListFragment is getting instantiated, onCreate and onCreate View is called, it just won't get displayed. :(
能否有人在这里让我知道如果我在我的ViewPager这里执行缺少什么？
Can anyone here let me know if I am missing anything here in my ViewPager implementation?
更新
当我打电话LaunchListFragment不使用Viewpager，我首先设置内容视图，并通过R.id.item_detail_container这是我想要显示的片段的FrameLayout的ID。请参考前面的main.xml
When I called LaunchListFragment without using Viewpager, I set the content view first and passed R.id.item_detail_container which is the id of the FrameLayout where I want the fragment to be displayed. Please refer to main.xml earlier
setContentView(R.layout.main.xml);
LaunchListFragment fragment = new LaunchListFragment();
fragment.newInstance(LIST_TYPE);
getSupportFragmentManager().beginTransaction()
.add(R.id.item_detail_container,
fragment).commit();
当我改变了这种使用ViewPager，我不知道在那里我指挥片段显示。在我的片段OnView由我膨胀fragment_launch_list并返回查看。但鉴于寻呼机怎么会知道在哪里设置的片段视图。难道是ID寻呼机里面呢？
When I changed this to use ViewPager, I am not sure where I'm directing the Fragment to be displayed. In my fragment onView I'm inflating fragment_launch_list and returning the View. But how will the view pager know where to set the fragment view. Is it inside the id pager?
我是一个绝对的初学者，我道歉，如果这一切都是幼稚的问题。
I'm an absolute beginner, I apologize if all these are naive questions.
干杯。
推荐答案
这是对您有用，
public class ViewPagerAdapter extends FragmentStatePagerAdapter {
private List<Fragment> fragments=null;
private FragmentManager fragmentManager=null;
public ViewPagerAdapter(FragmentManager fragmentManager,List<Fragment> fragments) {
super(fragmentManager);
this.fragments=fragments;
this.fragmentManager=fragmentManager;
}
@Override
public Fragment getItem(int position) {
fragmentManager.beginTransaction().commitAllowingStateLoss();
return fragments.get(position);
}
@Override
public int getCount() {
return fragments.size();
}
@Override
public void setPrimaryItem(ViewGroup container, int position, Object object)
{
super.setPrimaryItem(container,0,fragments.get(0));
}
@Override
public void notifyDataSetChanged()
{
super.notifyDataSetChanged();
}
@Override
public void destroyItem(ViewGroup collection, int position, Object view) {
fragmentManager.executePendingTransactions();
fragmentManager.saveFragmentInstanceState(fragments.get(position));
}
public void replaceItem(int position,Fragment fragment)
{
fragments.set(position, fragment);
this.notifyDataSetChanged();
}
}
MainActivity.java
MainActivity.java
public class MainActivity extends FragmentActivity implements OnPageChangeListener,TabListener
{
private android.support.v4.view.ViewPager mViewPager=null;
private ViewPagerAdapter mPagerAdapter=null;
private ActionBar action=null;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main_layout);
initilizeViewPager();
action=getActionBar();
action.setDisplayShowHomeEnabled(false);
action.setDisplayShowTitleEnabled(false);
action.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
}
public void initilizeViewPager()
{
mViewPager=(android.support.v4.view.ViewPager)findViewById(R.id.viewPager);
List<Fragment> fragments = new Vector<Fragment>();
fragments.add(LaunchListFragment.newInstance(select));
fragments.add(AddTeamFragment.newInstance());
fragments.add(thirdFragment.newInstance());
viewPagerAdapter=new ViewPagerAdapter();
mViewPager.setAdapter(viewPagerAdapter(getSupportFragmentManager(),fragments));
new setAdapterTask().execute();
mViewPager.setOnPageChangeListener(this);
}
private class setAdapterTask extends AsyncTask<Void,Void,Void>
{
protected Void doInBackground(Void... params)
{
return null;
}
@Override
protected void onPostExecute(Void result)
{
mViewPager.setAdapter(mPagerAdapter);
Tab first=action.newTab().setTag("first").setText("First").setTabListener(MainActivity.this);
Tab second=action.newTab().setTag("second").setText("Second").setTabListener(MainActivity.this);
Tab third=action.newTab().setTag("third").setText("Third").setTabListener(MainActivity.this);
action.addTab(first);
action.addTab(second);
action.addTab(third);
}
}
}
public void onPageScrollStateChanged(int arg0)
{}
public void onPageScrolled(int arg0, float arg1, int arg2)
{}
public void onPageSelected(int position)
{
getActionBar().setSelectedNavigationItem(position);
}
public void onTabReselected(Tab tab, FragmentTransaction ft) {}
public void onTabSelected(Tab tab, FragmentTransaction ft) {
mViewPager.setCurrentItem(tab.getPosition());
}
public void onTabUnselected(Tab tab, FragmentTransaction ft) {}
}
main_layout.xml
main_layout.xml
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="fill_parent"
android:layout_below="@android:id/tabs"
android:layout_height="fill_parent"/>
</RelativeLayout>
这篇关于麻烦ViewPager显示片段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！
