在 viewpager 中保存和恢复片段状态
Saving and restoring fragment state in viewpager
这可能是一个重复的问题，但似乎 none 提供的答案可以解决我的问题。所以我有一个 class 和 extends ViewPager 并且在水平导航中，我有 3 个页面。在 Fragment 的 onActivityCreated() 方法之一中，我正在调用服务器，获取一些数据并在 TableLayout 中插入 TableRows。现在我想保存这个确切的状态并在导航回相同的 Fragment.
时恢复它
我注意到一件奇怪的事情是，当我从一个 Tab 滑动到下一个然后再回到第一个时，第一个 Tab 的状态没有变化。然而，在从第一导航到第二导航到第三导航然后回到第一导航时，我失去了状态。除了使用 onSaveInstanceState() 之外，是否有任何方法可以保存 Fragment 的状态，然后在以后恢复它？因为这需要我手动将所有数据存储在 Bundle 中。这是我的 Fragment
public static class ProfileFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View fragmentView = inflater.inflate(R.layout.fragment_profile, container, false);
return fragmentView;
}
private final int EMPLOYER_TABLE_ROWS = 3;
private final int STUDENT_TABLE_ROWS = 7;
@Override
public void onActivityCreated(Bundle savedInstanceState){
super.onActivityCreated(savedInstanceState);
HasuraClient client = Hasura.getClient();
// make network calls to fetch data from server
HasuraUser user = client.getUser();
String[] role = user.getRoles();
if(role[1].equals(getString(R.string.student_role).toLowerCase())){
StudentProfileQuery query = new StudentProfileQuery(user.getId());
client.asRole(getString(R.string.student_role).toLowerCase()).useDataService()
.setRequestBody(query)
.expectResponseType(ProfileResponse.class)
.enqueue(new Callback<ProfileResponse, HasuraException>() {
@Override
public void onSuccess(ProfileResponse response) {
// Handle response
// get headingContainer
LinearLayout headingContainer = (LinearLayout) getView().findViewById(R.id.name_and_institute);
// get inflater object
LayoutInflater inflater = LayoutInflater.from(getContext());
// place name
TextView headingName = (TextView) inflater.inflate(R.layout.profile_page_title, headingContainer, false);
headingName.setText(response.getName());
headingContainer.addView(headingName, 0);
// place instituteName
TextView headingInstitution = (TextView) inflater.inflate(R.layout.profile_page_title, headingContainer, false);
headingInstitution.setText("Student" + " at " + response.getInstitution());
headingContainer.addView(headingInstitution, 1);
String[] field = {"Email", "Date Of Birth", "Gender", "Year of Admission", "Year of Passing", "Percentage",
"Resume URL"};
String[] detail = {response.getEmail(), response.getDob(), response.getGender(),
response.getYear_of_admission().toString(), response.getYear_of_passing().toString(),
response.getPercentage().toString(), response.getPath_to_cv()};
// insert TableRows in TableLayout
// get TableLayout container
TableLayout tableContainer = (TableLayout) getView().findViewById(R.id.profile_table);
for(int i = 0; i < STUDENT_TABLE_ROWS; i++){
// inflate TableRow
TableRow row = (TableRow) inflater.inflate(R.layout.profile_page_table, tableContainer, false);
// inflate element of col0 and set field, width
TextView col0Element = (TextView)inflater.inflate(R.layout.profile_table_row_element, row, false);
col0Element.setLayoutParams(new ViewGroup.LayoutParams(R.dimen.profile_col_0, ViewGroup.LayoutParams.WRAP_CONTENT));
col0Element.setText(field[i]);
// inflate element of col1 and set detail, width
TextView col1Element = (TextView)inflater.inflate(R.layout.profile_table_row_element, row, false);
col1Element.setLayoutParams(new ViewGroup.LayoutParams(R.dimen.profile_col_1, ViewGroup.LayoutParams.WRAP_CONTENT));
col1Element.setText(detail[i]);
// add col0 element to TableRow
row.addView(col0Element, 0);
// add col1 element to TableRow
row.addView(col1Element, 1);
// add TableRow to TableLayout
tableContainer.addView(row, i);
}
}
@Override
public void onFailure(HasuraException e) {
//Handle error
Toast.makeText(getContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
else if(role[1].equals(getString(R.string.employer_role).toLowerCase())){
EmployerProfileQuery query = new EmployerProfileQuery(user.getId());
client.asRole(getString(R.string.employer_role).toLowerCase()).useDataService()
.setRequestBody(query)
.expectResponseType(ProfileResponse.class)
.enqueue(new Callback<ProfileResponse, HasuraException>() {
@Override
public void onSuccess(ProfileResponse response) {
// Handle response
// get headingContainer
LinearLayout headingContainer = (LinearLayout) getView().findViewById(R.id.name_and_institute);
// get inflater object
LayoutInflater inflater = LayoutInflater.from(getContext());
// place name
TextView headingName = (TextView) inflater.inflate(R.layout.profile_page_title, headingContainer, false);
headingName.setText(response.getName());
headingContainer.addView(headingName, 0);
// place company name and designation
TextView headingCompany = (TextView) inflater.inflate(R.layout.profile_page_title, headingContainer, false);
headingCompany.setText(response.getDesignation() + " at " + response.getCompany());
headingContainer.addView(headingCompany, 1);
String[] field = {"Name", "Email", "Date Of Birth", "Gender"};
String[] detail = {response.getName(), response.getEmail(), response.getDob(), response.getGender()};
// insert TableRows in TableLayout
// get TableLayout container
TableLayout tableContainer = (TableLayout) getView().findViewById(R.id.profile_table);
for(int i = 0; i < EMPLOYER_TABLE_ROWS; i++){
// inflate TableRow
TableRow row = (TableRow) inflater.inflate(R.layout.profile_page_table, tableContainer, false);
// inflate element of col0 and set field, width
TextView col0Element = (TextView)inflater.inflate(R.layout.profile_table_row_element, row, false);
col0Element.setLayoutParams(new ViewGroup.LayoutParams(R.dimen.profile_col_0, ViewGroup.LayoutParams.WRAP_CONTENT));
col0Element.setText(field[i]);
// inflate element of col1 and set detail, width
TextView col1Element = (TextView)inflater.inflate(R.layout.profile_table_row_element, row, false);
col1Element.setLayoutParams(new ViewGroup.LayoutParams(R.dimen.profile_col_1, ViewGroup.LayoutParams.WRAP_CONTENT));
col1Element.setText(detail[i]);
// add col0 element to TableRow
row.addView(col0Element, 0);
// add col1 element to TableRow
row.addView(col1Element, 1);
// add TableRow to TableLayout
tableContainer.addView(row, i);
}
}
@Override
public void onFailure(HasuraException e) {
//Handle error
Toast.makeText(getContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
}
}
这里是 FragmentPagerAdapter
public class SectionsPagerAdapter extends FragmentPagerAdapter {
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 UI (defined as a static inner class below).
switch(position){
case 0:
return new ProfileFragment();
case 1:
return new MessagesFragment();
case 2:
return new HomeFragment();
}
return null;
}
@Override
public int getCount() {
// Show 3 total pages.
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return getString(R.string.profile_tab);
case 1:
return getString(R.string.messages_tab);
case 2:
return getString(R.string.home_tab);
}
return null;
}
}
除此之外还有另外 2 个 Fragment，我认为 post 不需要它们的代码。
提前致谢！
使用mViewPager.setOffscreenPageLimit(noOfPageYouWantToKeepInMemory);
这可能是一个重复的问题，但似乎 none 提供的答案可以解决我的问题。所以我有一个 class 和 extends ViewPager 并且在水平导航中，我有 3 个页面。在 Fragment 的 onActivityCreated() 方法之一中，我正在调用服务器，获取一些数据并在 TableLayout 中插入 TableRows。现在我想保存这个确切的状态并在导航回相同的 Fragment.
我注意到一件奇怪的事情是，当我从一个 Tab 滑动到下一个然后再回到第一个时，第一个 Tab 的状态没有变化。然而，在从第一导航到第二导航到第三导航然后回到第一导航时，我失去了状态。除了使用 onSaveInstanceState() 之外，是否有任何方法可以保存 Fragment 的状态，然后在以后恢复它？因为这需要我手动将所有数据存储在 Bundle 中。这是我的 Fragment
public static class ProfileFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
View fragmentView = inflater.inflate(R.layout.fragment_profile, container, false);
return fragmentView;
}
private final int EMPLOYER_TABLE_ROWS = 3;
private final int STUDENT_TABLE_ROWS = 7;
@Override
public void onActivityCreated(Bundle savedInstanceState){
super.onActivityCreated(savedInstanceState);
HasuraClient client = Hasura.getClient();
// make network calls to fetch data from server
HasuraUser user = client.getUser();
String[] role = user.getRoles();
if(role[1].equals(getString(R.string.student_role).toLowerCase())){
StudentProfileQuery query = new StudentProfileQuery(user.getId());
client.asRole(getString(R.string.student_role).toLowerCase()).useDataService()
.setRequestBody(query)
.expectResponseType(ProfileResponse.class)
.enqueue(new Callback<ProfileResponse, HasuraException>() {
@Override
public void onSuccess(ProfileResponse response) {
// Handle response
// get headingContainer
LinearLayout headingContainer = (LinearLayout) getView().findViewById(R.id.name_and_institute);
// get inflater object
LayoutInflater inflater = LayoutInflater.from(getContext());
// place name
TextView headingName = (TextView) inflater.inflate(R.layout.profile_page_title, headingContainer, false);
headingName.setText(response.getName());
headingContainer.addView(headingName, 0);
// place instituteName
TextView headingInstitution = (TextView) inflater.inflate(R.layout.profile_page_title, headingContainer, false);
headingInstitution.setText("Student" + " at " + response.getInstitution());
headingContainer.addView(headingInstitution, 1);
String[] field = {"Email", "Date Of Birth", "Gender", "Year of Admission", "Year of Passing", "Percentage",
"Resume URL"};
String[] detail = {response.getEmail(), response.getDob(), response.getGender(),
response.getYear_of_admission().toString(), response.getYear_of_passing().toString(),
response.getPercentage().toString(), response.getPath_to_cv()};
// insert TableRows in TableLayout
// get TableLayout container
TableLayout tableContainer = (TableLayout) getView().findViewById(R.id.profile_table);
for(int i = 0; i < STUDENT_TABLE_ROWS; i++){
// inflate TableRow
TableRow row = (TableRow) inflater.inflate(R.layout.profile_page_table, tableContainer, false);
// inflate element of col0 and set field, width
TextView col0Element = (TextView)inflater.inflate(R.layout.profile_table_row_element, row, false);
col0Element.setLayoutParams(new ViewGroup.LayoutParams(R.dimen.profile_col_0, ViewGroup.LayoutParams.WRAP_CONTENT));
col0Element.setText(field[i]);
// inflate element of col1 and set detail, width
TextView col1Element = (TextView)inflater.inflate(R.layout.profile_table_row_element, row, false);
col1Element.setLayoutParams(new ViewGroup.LayoutParams(R.dimen.profile_col_1, ViewGroup.LayoutParams.WRAP_CONTENT));
col1Element.setText(detail[i]);
// add col0 element to TableRow
row.addView(col0Element, 0);
// add col1 element to TableRow
row.addView(col1Element, 1);
// add TableRow to TableLayout
tableContainer.addView(row, i);
}
}
@Override
public void onFailure(HasuraException e) {
//Handle error
Toast.makeText(getContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
else if(role[1].equals(getString(R.string.employer_role).toLowerCase())){
EmployerProfileQuery query = new EmployerProfileQuery(user.getId());
client.asRole(getString(R.string.employer_role).toLowerCase()).useDataService()
.setRequestBody(query)
.expectResponseType(ProfileResponse.class)
.enqueue(new Callback<ProfileResponse, HasuraException>() {
@Override
public void onSuccess(ProfileResponse response) {
// Handle response
// get headingContainer
LinearLayout headingContainer = (LinearLayout) getView().findViewById(R.id.name_and_institute);
// get inflater object
LayoutInflater inflater = LayoutInflater.from(getContext());
// place name
TextView headingName = (TextView) inflater.inflate(R.layout.profile_page_title, headingContainer, false);
headingName.setText(response.getName());
headingContainer.addView(headingName, 0);
// place company name and designation
TextView headingCompany = (TextView) inflater.inflate(R.layout.profile_page_title, headingContainer, false);
headingCompany.setText(response.getDesignation() + " at " + response.getCompany());
headingContainer.addView(headingCompany, 1);
String[] field = {"Name", "Email", "Date Of Birth", "Gender"};
String[] detail = {response.getName(), response.getEmail(), response.getDob(), response.getGender()};
// insert TableRows in TableLayout
// get TableLayout container
TableLayout tableContainer = (TableLayout) getView().findViewById(R.id.profile_table);
for(int i = 0; i < EMPLOYER_TABLE_ROWS; i++){
// inflate TableRow
TableRow row = (TableRow) inflater.inflate(R.layout.profile_page_table, tableContainer, false);
// inflate element of col0 and set field, width
TextView col0Element = (TextView)inflater.inflate(R.layout.profile_table_row_element, row, false);
col0Element.setLayoutParams(new ViewGroup.LayoutParams(R.dimen.profile_col_0, ViewGroup.LayoutParams.WRAP_CONTENT));
col0Element.setText(field[i]);
// inflate element of col1 and set detail, width
TextView col1Element = (TextView)inflater.inflate(R.layout.profile_table_row_element, row, false);
col1Element.setLayoutParams(new ViewGroup.LayoutParams(R.dimen.profile_col_1, ViewGroup.LayoutParams.WRAP_CONTENT));
col1Element.setText(detail[i]);
// add col0 element to TableRow
row.addView(col0Element, 0);
// add col1 element to TableRow
row.addView(col1Element, 1);
// add TableRow to TableLayout
tableContainer.addView(row, i);
}
}
@Override
public void onFailure(HasuraException e) {
//Handle error
Toast.makeText(getContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
}
}
这里是 FragmentPagerAdapter
public class SectionsPagerAdapter extends FragmentPagerAdapter {
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 UI (defined as a static inner class below).
switch(position){
case 0:
return new ProfileFragment();
case 1:
return new MessagesFragment();
case 2:
return new HomeFragment();
}
return null;
}
@Override
public int getCount() {
// Show 3 total pages.
return 3;
}
@Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return getString(R.string.profile_tab);
case 1:
return getString(R.string.messages_tab);
case 2:
return getString(R.string.home_tab);
}
return null;
}
}
除此之外还有另外 2 个 Fragment，我认为 post 不需要它们的代码。
提前致谢！
使用mViewPager.setOffscreenPageLimit(noOfPageYouWantToKeepInMemory);