保存选项卡内的片段状态

本文介绍了保存选项卡内的片段状态的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我做了个动作条有两个选项卡 - 一个用于afragment和bfragment。 afragment包含一个按钮。点击afragment按钮，将导致其改为cfragment。但是，单击选项卡再次结果afragment被再次加载。我可以做prevent这算什么，基本上到标签，说：当有人点击你，加载最后一个片段的状态（在这种情况下，cfragment）？

I made an ActionBar with two tabs - one for afragment and bfragment. afragment contains a button. Clicking the button on afragment will result it to change to cfragment. However, clicking the tab again results to afragment being loaded again. What can I do to prevent this, to essentially say to the tab, "When somebody clicks on you, load the last fragment state (in this case, cfragment)?"

这是我的MainActivity.java：

This is my MainActivity.java:

public class MainActivity extends Activity { public static Context appContext; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); appContext = getApplicationContext(); //ActionBar ActionBar actionbar = getActionBar(); actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); ActionBar.Tab PlayerTab = actionbar.newTab().setText("Fragment A"); ActionBar.Tab StationsTab = actionbar.newTab().setText("Fragment B"); Fragment PlayerFragment = new AFragment(); Fragment StationsFragment = new BFragment(); PlayerTab.setTabListener(new MyTabsListener(PlayerFragment)); StationsTab.setTabListener(new MyTabsListener(StationsFragment)); actionbar.addTab(PlayerTab); actionbar.addTab(StationsTab); }

我TabListener：

My TabListener:

class MyTabsListener implements ActionBar.TabListener { public Fragment fragment; public MyTabsListener(Fragment fragment) { this.fragment = fragment; } @Override public void onTabReselected(Tab tab, FragmentTransaction ft) { Toast.makeText(MainActivity.appContext, "Reselected!", Toast.LENGTH_LONG).show(); } @Override public void onTabSelected(Tab tab, FragmentTransaction ft) { ft.replace(R.id.fragment_container, fragment); } @Override public void onTabUnselected(Tab tab, FragmentTransaction ft) { ft.remove(fragment); } }

最后，我AFragment.java：

And finally, my AFragment.java:

public class AFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // Inflate the layout for this fragment View view = inflater.inflate(R.layout.afragment, container, false); Button mButton = (Button) view.findViewById(R.id.button1); mButton.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { FragmentManager fragmentManager = getFragmentManager(); FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); CFragment fragment = new CFragment(); fragmentTransaction.replace(R.id.fragment_container, fragment); fragmentTransactionmit(); } }); return view; } }

我如何保存cfragment到标签以这样一种方式，点击第一个选项卡将不会导致再次afragment加载？谢谢你。

How do I save cfragment into the tab in such a way that clicking the first tab would not result to afragment loading again? Thank you.

推荐答案

的状态不会被保存，因为你每次更换标签时添加一个新的片段。

The state is not being saved because you are adding a new fragment every time you change tabs.

在'onTabUnselected`，不要删除，但分离/隐藏

In 'onTabUnselected`, don't remove, but detach/hide

public void onTabUnselected(Tab tab, FragmentTransaction ft) { if (fragment != null) { ft.detach(fragment); } }

而在 onTabSelected ，请检查是否片段，而不是已经存在的替换

And in onTabSelected, check to see if the fragment exists already instead of replacing

public void onTabSelected(Tab tab, FragmentTransaction ft) { fragment = mActivity.getSupportFragmentManager().findFragmentByTag(tag); if( fragment == null ) { fragment = Fragment.instantiate(mActivity, mClass.getName()); ft.add(R.id.fragment_container, fragment, tag); } else { ft.attach(fragment); } }