Android 碎片选项卡每次创建新的碎片对象
我想使用以下代码: ,但我看到它在每个交换机之间创建和删除片段。您能告诉我如何更改它吗?这样每个片段在开始时或第一次进入后只创建一次?谢谢 另外,我正在使用带有TabHost的Fragment,用于显示放置在其中的其他片段之一 更新: 每次从一个选项卡切换到另一个选项卡后,我都会在子片段中获得onCreateView和onActivityCreated方法。这不是因为这句台词吗Android 碎片选项卡每次创建新的碎片对象,android,android-tabhost,fragment,Android,Android Tabhost,Fragment,我想使用以下代码: ,但我看到它在每个交换机之间创建和删除片段。您能告诉我如何更改它吗?这样每个片段在开始时或第一次进入后只创建一次?谢谢 另外,我正在使用带有TabHost的Fragment,用于显示放置在其中的其他片段之一 更新: 每次从一个选项卡切换到另一个选项卡后,我都会在子片段中获得onCreateView和onActivityCreated方法。这不是因为这句台词吗 if (mLastTab != null) { if (mLastTab.fragment != null) {
if (mLastTab != null)
{
if (mLastTab.fragment != null)
{
ft.detach(mLastTab.fragment);
}
}
TabManager的完整源代码放在片段子类中:
public class TabManager implements TabHost.OnTabChangeListener
{
private final TabHost mTabHost;
private final int mContainerId;
private final HashMap<String, TabInfo> mTabs = new HashMap<String, TabInfo>();
TabInfo mLastTab;
final class TabInfo
{
private final String tag;
private final Class<?> clss;
private final Bundle args;
private Fragment fragment;
TabInfo(String _tag, Class<?> _class, Bundle _args)
{
tag = _tag;
clss = _class;
args = _args;
}
}
class DummyTabFactory implements TabHost.TabContentFactory
{
private final Context mContext;
public DummyTabFactory(Context context)
{
mContext = context;
}
@Override
public View createTabContent(String tag)
{
View v = new View(mContext);
v.setMinimumWidth(0);
v.setMinimumHeight(0);
return v;
}
}
public TabManager(TabHost tabHost, int containerId)
{
mTabHost = tabHost;
mContainerId = containerId;
mTabHost.setOnTabChangedListener(this);
}
public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args)
{
tabSpec.setContent(new DummyTabFactory(getActivity()));
String tag = tabSpec.getTag();
TabInfo info = new TabInfo(tag, clss, args);
// Check to see if we already have a fragment for this tab, probably
// from a previously saved state. If so, deactivate it, because our
// initial state is that a tab isn't shown.
info.fragment = getFragmentManager().findFragmentByTag(tag);
if (info.fragment != null && !info.fragment.isDetached())
{
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.detach(info.fragment);
ft.commit();
}
mTabs.put(tag, info);
mTabHost.addTab(tabSpec);
}
@Override
public void onTabChanged(String tabId)
{
TabInfo newTab = mTabs.get(tabId);
if (mLastTab != newTab)
{
FragmentTransaction ft = getFragmentManager().beginTransaction();
if (mLastTab != null)
{
if (mLastTab.fragment != null)
{
ft.detach(mLastTab.fragment);
}
}
if (newTab != null)
{
if (newTab.fragment == null)
{
newTab.fragment = Fragment.instantiate(getActivity(), newTab.clss.getName(), newTab.args);
ft.add(mContainerId, newTab.fragment, newTab.tag);
} else
{
ft.attach(newTab.fragment);
}
}
mLastTab = newTab;
ft.commit();
getFragmentManager().executePendingTransactions();
}
}
}
编辑:
我在单击选项卡后显示/隐藏片段,而不是附加/分离。但我不知道这是否正确。
解决方案:
public class TabManager implements TabHost.OnTabChangeListener
{
private final TabHost mTabHost;
private final int mContainerId;
private final HashMap<String, TabInfo> mTabs = new HashMap<String, TabInfo>();
TabInfo mLastTab;
final class TabInfo
{
private final String tag;
private final Class<?> clss;
private final Bundle args;
private Fragment fragment;
TabInfo(String _tag, Class<?> _class, Bundle _args)
{
tag = _tag;
clss = _class;
args = _args;
}
}
class DummyTabFactory implements TabHost.TabContentFactory
{
private final Context mContext;
public DummyTabFactory(Context context)
{
mContext = context;
}
@Override
public View createTabContent(String tag)
{
View v = new View(mContext);
v.setMinimumWidth(0);
v.setMinimumHeight(0);
return v;
}
}
public TabManager(TabHost tabHost, int containerId)
{
mTabHost = tabHost;
mContainerId = containerId;
mTabHost.setOnTabChangedListener(this);
}
public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args)
{
tabSpec.setContent(new DummyTabFactory(getActivity()));
String tag = tabSpec.getTag();
TabInfo info = new TabInfo(tag, clss, args);
// Check to see if we already have a fragment for this tab, probably
// from a previously saved state. If so, deactivate it, because our
// initial state is that a tab isn't shown.
info.fragment = getFragmentManager().findFragmentByTag(tag);
if (info.fragment != null && !info.fragment.isDetached())
{
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.detach(info.fragment);
ft.commit();
}
mTabs.put(tag, info);
mTabHost.addTab(tabSpec);
}
@Override
public void onTabChanged(String tabId)
{
TabInfo newTab = mTabs.get(tabId);
if (mLastTab != newTab)
{
android.support.v4.app.FragmentTransaction ft = ((FragmentActivity) getActivity()).getSupportFragmentManager().beginTransaction();
if (mLastTab != null)
{
if (mLastTab.fragment != null)
{
ft.hide(mLastTab.fragment);
}
}
if (newTab != null)
{
if (newTab.fragment == null)
{
newTab.fragment = Fragment.instantiate(getActivity(), newTab.clss.getName(), newTab.args);
ft.add(mContainerId, newTab.fragment, newTab.tag);
} else
{
ft.show(newTab.fragment);
}
}
mLastTab = newTab;
ft.commit();
getFragmentManager().executePendingTransactions();
}
}
}
它不会每次都创建一个新片段,它只在片段未附加到选项卡时创建,即newTab.fragment在onTabChanged方法中为null
if (newTab.fragment == null) {
newTab.fragment = Fragment.instantiate(mActivity,
newTab.clss.getName(), newTab.args);
ft.add(mContainerId, newTab.fragment, newTab.tag);
} else {
ft.attach(newTab.fragment);
}
你能告诉我如何在tabhost上使用它吗?不明白你的问题-它已经在使用tabhost了,对吗?我正在使用这个tabhost和searchview,我需要在单击search时重新创建片段。我不想在更改选项卡时重新创建。