我在使用Fragments
和屏幕旋转时遇到了问题。
我的应用有一个MainActivity
,通过选项卡式操作栏来切换Fragments
。以下是选项卡式操作栏的代码以及当选项卡被选择时的处理方式:
private class MyTabListener <T extends android.support.v4.app.Fragment> implements ActionBar.TabListener {
private android.support.v4.app.Fragment mFragment;
private final Activity mActivity;
private final String mTag;
private final Class<T> mClass;
public MyTabListener(SherlockFragmentActivity activity, String tag, Class<T> clz) {
mActivity = activity;
mTag = tag;
mClass = clz;
}
@Override
public void onTabSelected(Tab tab, android.support.v4.app.FragmentTransaction ft) {
if (mFragment == null){ // check to see if the fragment has already been initialised. If not create a new one.
mFragment = android.support.v4.app.Fragment.instantiate(mActivity, mClass.getName());
ft.add(android.R.id.content,mFragment,mTag);
} else {
ft.attach(mFragment); // if the fragment has been initialised attach it to the current activity
}
}
@Override
public void onTabUnselected(Tab tab, android.support.v4.app.FragmentTransaction ft) {
if (mFragment != null){
ft.detach(mFragment); // when a fragment is no longer needed, detach it from the activity but dont destroy it
}
}
@Override
public void onTabReselected(Tab tab, android.support.v4.app.FragmentTransaction ft) {
}
我认为,在应用程序首次以纵向模式加载时,一切都正常运作。但是当我旋转设备时,某种原因会导致另一个
Fragment1
的实例被添加,并且在选择另一个选项卡后不会被分离。当我旋转回纵向模式时,情况也是如此。我尝试在我的
Fragments
中使用setRetainInstance(true);
,但这没有起作用。在旋转之前,我需要重写某个方法或对我的
Fragments
进行某些操作吗?提前感谢您的帮助。
编辑:我现在知道当活动重新创建时,会再次调用 onTabSelected。这可能是我遇到的关于片段被多次连接的问题的原因吗?
这是我的活动onCreate方法。
super.onCreate(savedInstanceState);
if (savedInstanceState == null) {
//setContentView(R.layout.main);
}
// Create the Action Bar with tabs
ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
actionBar.setDisplayShowTitleEnabled(false);
//create the tab for track and add it to the action bar.
Tab tab = actionBar.newTab()
.setText("Track")
.setTabListener(new MyTabListener<TrackingFragment>(this,"track",TrackingFragment.class));
actionBar.addTab(tab);
//create the tab for ski tracks and add it to the action bar.
tab = actionBar.newTab()
.setText("Something Tracks")
.setTabListener(new MyTabListener<TrackListFragment>(this,"somethingtracks",TrackListFragment.class));
actionBar.addTab(tab);
//create the tab for photos and add it to the action bar.
tab = actionBar.newTab()
.setText("Photos")
.setTabListener(new MyTabListener<PhotoFragment>(this,"photos",PhotoFragment.class));
actionBar.addTab(tab);
public MyTabListener(SherlockFragmentActivity activity, String tag, Class<T> clz)
... 一个活动、一个标签和一个类。没有传入任何片段。 - Barak