Question

我正在尝试开发一个应用程序，其要求是在关闭应用程序后保留Tab，或突然如果应用程序在运行时被销毁

我的应用有3个标签，我在第二个标签中添加商品＆＃34; CheckList＆＃34; 当我关闭我的应用程序第二个标签时，再次使用新页面而不是之前添加的项目

即使关闭了应用程序，我希望我的应用程序与图片2相同，但似乎每次关闭应用程序选项卡时都会显示为图片1

Psuedo代码：

public class MainActivity extends AppCompatActivity implements ActionBar.TabListener {

    SectionsPagerAdapter mSectionsPagerAdapter;

    ViewPager mViewPager;
    public Fragment fragment;
    private FragmentActivity myContext;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final ActionBar actionBar = getSupportActionBar();
        View viewActionBar = getLayoutInflater().inflate(R.layout.titlebar, null);
        ActionBar.LayoutParams params = new ActionBar.LayoutParams(//Center the textview in the ActionBar !
                ActionBar.LayoutParams.WRAP_CONTENT,
                ActionBar.LayoutParams.MATCH_PARENT
                );
        TextView textviewTitle = (TextView) viewActionBar.findViewById(R.id.mytext);
        textviewTitle.setText("Application");
        actionBar.setCustomView(viewActionBar, params);
        actionBar.setDisplayShowCustomEnabled(true);
        actionBar.setDisplayShowTitleEnabled(false);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mSectionsPagerAdapter);
        mViewPager.setOffscreenPageLimit(2);


        // For each of the sections in the app, add a tab to the action bar.
        for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
            // Create a tab with text corresponding to the page title defined by
            // the adapter. Also specify this Activity object, which implements
            // the TabListener interface, as the callback (listener) for when
            // this tab is selected.
            actionBar.addTab(actionBar.newTab().setText(mSectionsPagerAdapter.getPageTitle(i)).setTabListener(this));
        }
    }

    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            Fragment fragment = null;
            switch(position){
                case 0:
                    fragment = new FirstTab();
                    break;
                case 1:
                    fragment = new SecondTab();

                    break;
                case 2:
                    fragment = new ThirdTab();

            }
            return fragment;
        }

第二个标签代码：

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setRetainInstance(true);
        if(view==null) {
            view = inflater.inflate(R.layout.tab2, container, false);
// retain this fragment


            bt = (ImageView) view.findViewById(R.id.imageview3);
            tl = (TableLayout) view.findViewById(R.id.table);


          public void onSaveInstanceState(Bundle savedInstanceState) {

        super.onSaveInstanceState(savedInstanceState);

    }

我被困在这里，你能告诉我如何使用上述方法保存此标签如何保留？

我看到很少有答案涉及保留片段，但它没有解决我的问题

我是Android开发新手，请尽量帮助解决此问题

Answer 1

您无法保留Fragment个实例。

相反，你应该坚持和恢复Fragment的状态。（例如，使用SharedPreferences）

一旦App被销毁或关闭，如何保留片段

1 个答案: