我有一个包含三个 fragment 的 fragment Activity 。
public class MainActivity extends SherlockFragmentActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActionBar bar = getSupportActionBar();
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
ActionBar.Tab tab1 = bar.newTab();
ActionBar.Tab tab2 = bar.newTab();
ActionBar.Tab tab3 = bar.newTab();
tab1.setText("");
tab1.setIcon(R.drawable.abs__ic_menu_share_holo_dark);
tab2.setText("");
tab2.setIcon(R.drawable.abs__ic_voice_search);
tab3.setText("");
tab3.setIcon(R.drawable.abs__ic_cab_done_holo_dark);
if (savedInstanceState == null) {
tab1.setTabListener(new MyTabListener());
tab2.setTabListener(new MyTabListener());
tab3.setTabListener(new MyTabListener());
bar.addTab(tab1);
bar.addTab(tab2);
bar.addTab(tab3);
}
}
private class MyTabListener implements ActionBar.TabListener {
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
switch (tab.getPosition()) {
case 0:
FeedsActivity frag = new FeedsActivity();
ft.replace(android.R.id.content, frag);
return;
case 1:
ProfileActivity frag2 = new ProfileActivity();
ft.replace(android.R.id.content, frag2);
return;
case 2:
MyMemoirsActivity frag3 = new MyMemoirsActivity();
ft.replace(android.R.id.content, frag3);
return;
}
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
}
}
这是第一个 fragment ，
public class FeedsActivity extends SherlockFragment {
public static String[] MainCategory;
public static String[] MainCategoryId;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup group,
Bundle saved) {
setRetainInstance(true);
return inflater.inflate(R.layout.activity_feeds, group, false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
new GetMainCategory(getActivity()).execute();
}
}
当我选择第二个选项卡然后选择第一个选项卡时，会再次调用第一个 fragment 中的异步任务。如何保留第一个 fragment 的状态以便创建一次 View ？我使用了 setRetainInstance(true) 但没有用。
最佳答案
我通过使用显示和隐藏而不是附加和分离解决了这个问题。
private class MyTabListener implements ActionBar.TabListener {
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
switch (tab.getPosition()) {
case 0:
if (frag1 == null) {
// If not, instantiate and add it to the activity
frag1 = Fragment.instantiate(getApplicationContext(),
FeedsActivity.class.getName());
ft.add(android.R.id.content, frag1, "Feeds");
} else {
// If it exists, simply attach it in order to show it
ft.show(frag1);
}
return;
case 1:
if (frag2 == null) {
// If not, instantiate and add it to the activity
frag2 = Fragment.instantiate(getApplicationContext(),
ProfileActivity.class.getName());
ft.add(android.R.id.content, frag2, "Profile");
} else {
// If it exists, simply attach it in order to show it
ft.show(frag2);
}
return;
case 2:
if (frag3 == null) {
// If not, instantiate and add it to the activity
frag3 = Fragment.instantiate(getApplicationContext(),
History.class.getName());
ft.add(android.R.id.content, frag3, "History");
} else {
// If it exists, simply attach it in order to show it
ft.show(frag3);
}
return;
}
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
if (frag1 != null) {
// Detach the fragment, because another one is being attached
switch (tab.getPosition()) {
case 0:
ft.hide(frag1);
return;
case 1:
ft.hide(frag2);
return;
case 2:
ft.hide(frag3);
return;
}
}
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
}
}
关于android - 选择 ActionbarSherlock 选项卡时重新创建 fragment ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16075790/