我尝试了从API 样品code,并没有真正的工作让我实现我自己的:
I tried out the sample code from the API and it didn't really work so I implemented my own:
FragmentPagerSupport
public class FragmentPagerSupport extends FragmentActivity {
static final int NUM_ITEMS = 10;
MyAdapter mAdapter;
ViewPager mPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mAdapter = new MyAdapter(getSupportFragmentManager());
Log.i("Pager", "mAdapter = " + mAdapter.toString());
mPager = (ViewPager)findViewById(R.id.pager);
if (mPager == null)
Log.i("Pager", "mPager = null");
else
Log.i("Pager", "mPager = " + mPager.toString());
Log.i("Pager", "Setting Pager Adapter");
mPager.setAdapter(mAdapter);
}
public static class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
Log.i("Pager", "MyAdapter constructor");
}
@Override
public int getCount() {
Log.i("Pager", "MyAdapter.getCount()");
return NUM_ITEMS;
}
@Override
public Fragment getItem(int position) {
Log.i("Pager", "MyAdapter.getItem()");
return TestFragment.newInstance(position);
}
}
public static class TestFragment extends Fragment {
public static TestFragment newInstance(int position) {
Log.i("Pager", "TestFragment.newInstance()");
TestFragment fragment = new TestFragment();
Bundle args = new Bundle();
args.putInt("position", position);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
Log.i("Pager", "TestFragment.onCreateView()");
LinearLayout layout = (LinearLayout)inflater.inflate(R.layout.fragment_item, null);
int position = getArguments().getInt("position");
TextView tv = (TextView)layout.findViewById(R.id.text);
tv.setText("Fragment # " + position);
tv.setTextColor(Color.WHITE);
tv.setTextSize(30);
return layout;
}
}
}
的main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</LinearLayout>
fragment_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:id="@+id/text"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:text="@string/hello"
/>
</LinearLayout>
我的问题是,而不是创建一个新的片段
实例的每个左,右用户刷卡时,我该如何拯救一个片段的状态(一些数据结构)和然后恢复呢?
My question is, instead of creating a new Fragment
instance each time the user swipes left and right, how do I save a fragment's state (to some data structure) and then restore it?
的 API演示似乎并未有任何状态信息保存code在所有。
The API demo doesn't seem to have any state information saving code at all.
使用 ViewPager.setOffscreenPageLimit()
在 FragmentActivity
ViewPager pager = (ViewPager) findViewById(R.id.viewPager);
pager.setOffscreenPageLimit(2);
多见于How我告诉我的自定义FragmentPagerAdapter停止破坏我的片段?