在StackOverflow（DEMO）的回答中，我成功创建了我的项目，并根据我的需要进行了一些修改。
我可以在主布局中添加N个片段（viewpages）并删除它们，直到页数变为零。
现在，我遇到了一个问题。其中一个，如果我从当前活动中移动这个页面到其他活动，或者如果我关闭我的应用程序然后回来，我只能看到最初的静态添加片段。
我不仅希望看到初始页面，还希望看到之前添加的页面。我应该使用SharedPreferences存储动态添加的片段吗？
这是我的源代码： 我的主要布局：
<?xml version="1.0" encoding="utf-8"?>
<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/pager"
android:layout_width="match_parent"
android:layout_height="900dp"
/>
<Button
android:id="@+id/show_items"
android:layout_width="40dp"
android:layout_height="wrap_content"
android:layout_marginTop="200dp"
android:textColor="#ffffff"
android:background="#49a942"
android:textAppearance="?android:attr/textAppearanceLarge"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:text="+" />
<Button
android:id="@+id/grid_apps_show"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/pager"
android:layout_alignParentBottom="true"
android:text="Apps"
/>
</RelativeLayout>
我的MainActivity类：
public class MainActivity extends FragmentActivity implements TextProvider{
Button home;
private ViewPager mPager;
private MyPagerAdapter mAdapter;
private ArrayList<String> mEntries = new ArrayList<String>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
home = (Button) findViewById(R.id.show_items);
mEntries.add("pos 1");
mPager = (ViewPager) findViewById(R.id.pager);
home.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
MainActivity.this);
alertDialogBuilder.setTitle("Add/Delete Screens");
alertDialogBuilder
.setCancelable(false)
.setNegativeButton("+",new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int id) {
addNewItem();
}
})
.setPositiveButton("-",new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int id) {
removeCurrentItem();
}
});
// create alert dialog
AlertDialog alertDialog = alertDialogBuilder.create();
// show it
alertDialog.show();
}
});
mAdapter = new MyPagerAdapter(this.getSupportFragmentManager(), this);
mPager.setAdapter(mAdapter);
}
private void addNewItem() {
mEntries.add("Pages");
mAdapter.notifyDataSetChanged();
}
private void removeCurrentItem() {
int position = mPager.getCurrentItem();
if(position != 0){
mEntries.remove(position);
mAdapter.notifyDataSetChanged();
}
else{
Toast.makeText(getApplicationContext(), "Minimum Screens are one!", Toast.LENGTH_LONG).show();
}
}
@Override
public String getTextForPosition(int position) {
return mEntries.get(position);
}
@Override
public int getCount() {
return mEntries.size();
}
private class MyPagerAdapter extends FragmentPagerAdapter {
private TextProvider mProvider;
private long baseId = 0;
public MyPagerAdapter(FragmentManager fm, TextProvider provider) {
super(fm);
this.mProvider = provider;
}
@Override
public Fragment getItem(int position) {
if(position == 0){
return ScreenOne.newInstance(mProvider.getTextForPosition(position));
}
if(position == 1){
return ScreenTwo.newInstance(mProvider.getTextForPosition(position));
}
return ScreenTwo.newInstance(mProvider.getTextForPosition(position));
}
@Override
public int getCount() {
return mProvider.getCount();
}
//this is called when notifyDataSetChanged() is called
@Override
public int getItemPosition(Object object) {
// refresh all fragments when data set changed
return PagerAdapter.POSITION_NONE;
}
@Override
public long getItemId(int position) {
// give an ID different from position when position has been changed
return baseId + position;
}
/**
* Notify that the position of a fragment has been changed.
* Create a new ID for each position to force recreation of the fragment
* @param n number of items which have been changed
*/
public void notifyChangeInPosition(int n) {
// shift the ID returned by getItemId outside the range of all previous fragments
baseId += getCount() + n;
}
}
}
my fragment one:
public class ScreenOne extends Fragment {
private String mText;
public static ScreenOne newInstance(String text) {
ScreenOne f = new ScreenOne(text);
return f;
}
public ScreenOne() {
}
public ScreenOne(String text) {
this.mText = text;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.screen_one, container, false);
((TextView) root.findViewById(R.id.position_one)).setText(mText);
return root;
}
}
my fragment two:
public class ScreenTwo extends Fragment {
private String mText;
public static ScreenTwo newInstance(String text) {
ScreenTwo f = new ScreenTwo(text);
return f;
}
public ScreenTwo() {
}
public ScreenTwo(String text) {
this.mText = text;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.screen_two, container, false);
((TextView) root.findViewById(R.id.position_two)).setText(mText);
return root;
}
}
谢谢＆amp;问候， 阿迪亚。 Ĵ
答案 0 :(得分：2)
只需在FragmentpagerAdapter中重写此方法：
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(ViewGroup container, int position, Object object);
}
并删除：
super.destroyItem(ViewGroup container, int position, Object object);