我正在处理的应用在TabLayout中有3个标签。每个都包含一个列表视图。另外我使用FragmentStatePageAdapter和自定义适配器。当您单击ListView中的项目时，它会启动一个活动。在活动中完成任务后，它会更新一些全局数组数据。接下来，用户可以点击手机上的后退按钮返回。这就是问题所在。
现在Tab1永远不会改变，我后来希望实现返回将它设置为Tab1。这是后来的担心。问题是中间选项卡不会重新加载。我理解原因是因为中间选项卡已经创建，所以在视觉上滑动效果看起来很准确。 Tab3将来自Tab1，因为它尚未加载。
我尝试了各种监听器，在tablayout Fragment中使用onResume。我的代码中的任何地方都没有notifydatasetchange，并且无法实现这一点。我认为我已经以某种方式实现了一些错误并超越了正确的解决方案，因为我已经尝试了很多这样的事情。
以下是一些有助于了解我如何设置所有内容的代码。
MainActivity
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create the adapter that will return a fragment for each of the three primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(container);
mViewPager.setAdapter(mSectionsPagerAdapter);
mViewPager.setOffscreenPageLimit(0);
//more
final TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
tabLayout.setScrollPosition(0, 0f, true);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
SectionsPagerAdapter
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
protected Context mContext;
public SectionsPagerAdapter( FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
int number = position;
switch (number) {
case 0: // Fragment # 0 - This will show FirstFragment
return TabFragment1.newInstance();
case 1: // Fragment # 0 - This will show FirstFragment different title
return TabFragment2.newInstance();
case 2: // Fragment # 1 - This will show SecondFragment
return TabFragment3.newInstance();
default:
return null;
}
// return PlaceholderFragment.newInstance(position + 1);
}
@Override
public int getCount() {
// Show 3 total pages.
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "All";
case 1:
return "Unfinished";
case 2:
return "Completed";
}
return null;
}}
MyAdapter
public class SectionsPagerAdapter extends FragmentStatePagerAdapter {
protected Context mContext;
public SectionsPagerAdapter( FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
int number = position;
switch (number) {
case 0: // Fragment # 0 - This will show FirstFragment
return TabFragment1.newInstance();
case 1: // Fragment # 0 - This will show FirstFragment different title
return TabFragment2.newInstance();
case 2: // Fragment # 1 - This will show SecondFragment
return TabFragment3.newInstance();
default:
return null;
}
// return PlaceholderFragment.newInstance(position + 1);
}
@Override
public int getCount() {
// Show 3 total pages.
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "All";
case 1:
return "Unfinished";
case 2:
return "Completed";
}
return null;
}}
Fragment1 （所有三个片段完全相同）
public class TabFragment1 extends android.support.v4.app.Fragment {
public ArrayList<String> mylist1 = new ArrayList<>();
// newInstance constructor for creating fragment with arguments
public static TabFragment1 newInstance() {
TabFragment1 fragmentFirst = new TabFragment1();
Bundle args = new Bundle();
//pass a list or something?
fragmentFirst.setArguments(args);
return fragmentFirst;
}
// Store instance variables based on arguments passed
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
// Inflate the view for the fragment based on layout XML
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View rootView = inflater.inflate(R.layout.fragment_main, container, false);
mylist1.clear();
for (int i = 0; i < arrayInt.length; i++) {
mylist1.add(array[i]);
}
final ListView listView = (ListView) rootView.findViewById(R.id.text_label);
MyAdapter adapter = new MyAdapter(getContext(), mylist1);
listView.setAdapter(adapter);
//Click on Item
//selecting items
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//goes to new activity passing the item name
Intent intent = new Intent(view.getContext(), MapsActivity.class);
Bundle b = new Bundle();
//get text for current item
//String textGet = listView.getItemAtPosition(position).toString();
String textGet = mylist1.get(position);
//put text into a bundle and add to intent
intent.putExtra("text", textGet);
//get position to carry integer
intent.putExtra("position", position);
intent.putExtras(b);
//begin other activity
startActivity(intent);
}
});
return rootView;
}
这是一个较旧的尝试通知数据集已更改但没有运气。我把它放在碎片本身。
public void onResume(){
super.onResume();
Log.e("Frag2", "Refresh Test");
// a check so it doesnt run first time starting app and crashing
if (g != 0) {
updateData();
}
g = 1;
}
private void updateData(){
Log.e("Frag2", "Refresh Test");
this.mylist2.clear();
for (int i = 0; i < arrayInt.length; i++) {
if (arrayInt[i] == 1) {
this.mylist2.add(array[i]);
}
}
adapter = new MyAdapter(getContext(), this.mylist2);
adapter.notifyDataSetChanged();
}