如果在其上按下另一个片段时，如何保存片段中的视图状态。
Say，在android中，一个片段（FragA）被添加到backstack，另一个片段（FragB）出现在顶部。现在回击时，FragA会到达顶部并调用onCreateView（）。现在，在FragB被推到它之前，我已经将FragA置于特定状态。
我的问题是如何将FragA恢复到以前的状态？有没有办法保存状态，如果有，那么我应该覆盖哪种方法？
这是我的FragmentActivity： -
package com.android.demoresponsevision.tab;
import java.util.HashMap;
import java.util.Stack;
import com.android.demoresponsevision.R;
import com.android.demoresponsevision.fragment.HomeScreen;
import com.android.demoresponsevision.fragment.SecondHomeScreen;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.widget.TabHost;
import android.widget.TabHost.OnTabChangeListener;
import android.widget.TabHost.TabContentFactory;
import android.widget.TextView;
public class TabActivity extends FragmentActivity implements
OnTabChangeListener {
TextView txt;
private TabHost mTabHost;
private HashMap mapTabInfo = new HashMap();
private TabInfo mLastTab = null;
public static Stack<Fragment> mStackTabHomeScreen = new Stack<Fragment>();
public static Stack<Fragment> mStackTabSecondScreen = new Stack<Fragment>();
private HomeScreen mHomeScreen;
private SecondHomeScreen mSecondHomeScreen;
private FragmentTransaction fragmentTransaction;
private FragmentManager fragmentManager;
private class TabInfo {
private String tag;
private Class clss;
private Bundle args;
private Fragment fragment;
TabInfo(String tag, Class clazz, Bundle args) {
this.tag = tag;
this.clss = clazz;
this.args = args;
}
}
class TabFactory implements TabContentFactory {
private final Context mContext;
/** * @param context */
public TabFactory(Context context) {
mContext = context;
}
public View createTabContent(String tag) {
View v = new View(mContext);
v.setMinimumWidth(0);
v.setMinimumHeight(0);
return v;
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.tabs);
mHomeScreen = new HomeScreen();
mSecondHomeScreen = new SecondHomeScreen();
fragmentManager = getSupportFragmentManager();
initialiseTabHost(savedInstanceState);
if (savedInstanceState != null) {
mTabHost.setCurrentTabByTag(savedInstanceState.getString("tab"));
}
}
protected void onSaveInstanceState(Bundle outState) {
outState.putString("tab", mTabHost.getCurrentTabTag()); // save the tab
// selected
super.onSaveInstanceState(outState);
}
/**
* Step 2: Setup TabHost
*/
private void initialiseTabHost(Bundle args) {
mTabHost = (TabHost) findViewById(android.R.id.tabhost);
mTabHost.setup();
TabInfo tabInfo = null;
TabActivity.addTab(this, this.mTabHost, this.mTabHost
.newTabSpec("Tab1").setIndicator("HomeScreen"),
(tabInfo = new TabInfo("Tab1", HomeScreen.class, args)));
this.mapTabInfo.put(tabInfo.tag, tabInfo);
TabActivity.addTab(this, this.mTabHost, this.mTabHost
.newTabSpec("Tab2").setIndicator("SecondScreen"),
(tabInfo = new TabInfo("Tab2", SecondHomeScreen.class, args)));
this.mapTabInfo.put(tabInfo.tag, tabInfo);
// Default to first tab
this.onTabChanged("Tab1");
//
mTabHost.setOnTabChangedListener((OnTabChangeListener) this);
}
private static void addTab(TabActivity activity, TabHost tabHost,
TabHost.TabSpec tabSpec, TabInfo tabInfo) { // Attach a Tab view
// factory to the spec
tabSpec.setContent(activity.new TabFactory(activity));
String tag = tabSpec.getTag();
// 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.
tabInfo.fragment = activity.getSupportFragmentManager()
.findFragmentByTag(tag);
if (tabInfo.fragment != null && !tabInfo.fragment.isDetached()) {
FragmentTransaction ft = activity.getSupportFragmentManager()
.beginTransaction();
ft.detach(tabInfo.fragment);
ft.commit();
activity.getSupportFragmentManager().executePendingTransactions();
}
tabHost.addTab(tabSpec);
}
/**
* (non-Javadoc) * @see
* android.widget.TabHost.OnTabChangeListener#onTabChanged(java.lang.String)
*/
public void onTabChanged(String tag) {
TabInfo newTab = (TabInfo) this.mapTabInfo.get(tag);
if(mTabHost.getCurrentTabTag()=="Tab1") {
if(mStackTabHomeScreen.size()>0) {
Fragment fragment=mStackTabHomeScreen.get(mStackTabHomeScreen.size()-1);
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.realtabcontent, fragment);
fragmentTransaction.commit();
}
else {
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.realtabcontent, mHomeScreen);
mStackTabHomeScreen.add(mHomeScreen);
fragmentTransaction.commit();
}
}
if(mTabHost.getCurrentTabTag()=="Tab2") {
if(mStackTabSecondScreen.size()>0) {
Fragment fragment=mStackTabSecondScreen.get(mStackTabSecondScreen.size()-1);
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.realtabcontent, fragment);
fragmentTransaction.commit();
}
else {
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.realtabcontent, mSecondHomeScreen);
mStackTabSecondScreen.add(mSecondHomeScreen);
fragmentTransaction.commit();
}
}
/*if (mLastTab != newTab)
{
FragmentTransaction ft = this.getSupportFragmentManager().beginTransaction();
if (mLastTab != null)
{
if (mLastTab.fragment != null)
{
ft.detach(mLastTab.fragment);
}
}
if (newTab != null) {
if (newTab.fragment == null)
{
newTab.fragment = Fragment.instantiate(this,newTab.clss.getName(), newTab.args);
ft.add(R.id.realtabcontainer, newTab.fragment, newTab.tag);
} else {
ft.attach(newTab.fragment);
}
}
mLastTab = newTab;
ft.commit();
this.getSupportFragmentManager().executePendingTransactions();
}*/
}
@Override
public void onBackPressed() {
if(mTabHost.getCurrentTabTag()=="Tab1"){
if(mStackTabHomeScreen.size()>1) {
Fragment fragment=mStackTabHomeScreen.get(mStackTabHomeScreen.size()-2);
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.realtabcontent, fragment);
mStackTabHomeScreen.pop();
fragmentTransaction.commit();
}
/*if(mStackTabA.size()==2){
Fragment frag=mStackTabA.get(0);
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.realtabcontainer, frag);
mStackTabA.pop();
fragmentTransaction.commit();
}
else {
mStackTabA.clear();
mStackTabA.add(mFirstFragment);
} */
}
if(mTabHost.getCurrentTabTag()=="Tab2"){
if(mStackTabSecondScreen.size()>1) {
Fragment fragment=mStackTabSecondScreen.get(mStackTabSecondScreen.size()-2);
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.realtabcontent, fragment);
mStackTabSecondScreen.pop();
fragmentTransaction.commit();
}
/*if(mStackTabB.size()==2){
Fragment frag=mStackTabB.get(0);
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.realtabcontainer, frag);
mStackTabB.pop();
fragmentTransaction.commit();
}
else {
mStackTabB.clear();
mStackTabB.add(mFirstFragment);
} */
}
}
}