Question

我将这个监听器用于制表符但是当屏幕旋转时，所有碎片都会移动到初始状态：

public static class TabListener implements ActionBar.TabListener {

        private final Activity mActivity;
        /**
         * HashMap with tab tag and tab frament
         */
        private final HashMap<String, TabInfo> mTabs = new HashMap<String, TabInfo>();

        /**
         * Auxiliary class for storing tab info
         * 
         */
        static final class TabInfo {
            private final String mTag;
            private final Class<? extends Fragment> mClass;
            private Fragment mFragment;

            TabInfo(String tag, Class<? extends Fragment> class_) {
                mTag = tag;
                mClass = class_;
            }
        }

        public TabListener(Activity activity) {
            mActivity = activity;
        }

        public void addTab(String tag, Class<? extends Fragment> class_) {
            mTabs.put(tag, new TabInfo(tag, class_));
        }

        /* The following are each of the ActionBar.TabListener callbacks */

        @Override
        public void onTabSelected(Tab tab, FragmentTransaction ft) {
            // Check if the fragment is already initialized
            TabInfo tabInfo = mTabs.get(tab.getTag());

            Fragment prevFragment = ((SherlockFragmentActivity) mActivity)
                    .getSupportFragmentManager().findFragmentByTag(
                            (String) tab.getTag());
            if (prevFragment != null) {
                tabInfo.mFragment = prevFragment;
            }

            if (tabInfo.mFragment == null) {
                // If not, instantiate and add it to the activity
                tabInfo.mFragment = Fragment.instantiate(mActivity,
                        tabInfo.mClass.getName());
                ft.add(android.R.id.content, tabInfo.mFragment, tabInfo.mTag);
            } else {
                // If it exists, simply attach it in order to show it
                ft.attach(tabInfo.mFragment);
            }
        }

        @Override
        public void onTabUnselected(Tab tab, FragmentTransaction ft) {
            TabInfo tabInfo = mTabs.get(tab.getTag());
            if (tabInfo.mFragment != null) {
                // Detach the fragment, because another one is being attached
                ft.detach(tabInfo.mFragment);
            }
        }

        @Override
        public void onTabReselected(Tab tab, FragmentTransaction ft) {
            // User selected the already selected tab. Usually do nothing.
        }
    }

Answer 1

protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);

...

CustomFragment fragment;
if (savedInstanceState != null) {
    fragment = (CustomFragment) getSupportFragmentManager().findFragmentByTag("customtag");
} else {
    fragment = new CustomFragment();
    getSupportFragmentManager().beginTransaction().add(R.id.container, fragment, "customtag").commit(); 
}

...

}

尝试这一定会对你有所帮助。

Answer 2

在片段中调用setRetainInstance(true)。这将在屏幕旋转后保持状态。但请注意片段生命周期中的更改，请参阅Docs。

屏幕旋转后片段状态未保存（使用带选项卡的ActionBar）

2 个答案: