Question

我的应用程序中有一个标签页面，

这里有一些简化的代码：

@SuppressLint("NewApi")
public class Rhino68PanelActivity extends FragmentActivity implements ActionBar.TabListener {

static String TAG = "Rhino68PanelActivty";

/**
 * The {@link android.support.v4.view.PagerAdapter} that will provide
 * fragments for each of the sections. We use a
 * {@link android.support.v4.app.FragmentPagerAdapter} derivative, which
 * will keep every loaded fragment in memory. If this becomes too memory
 * intensive, it may be best to switch to a
 * {@link android.support.v4.app.FragmentStatePagerAdapter}.
 */
SectionsPagerAdapter mSectionsPagerAdapter;

/**
 * The {@link ViewPager} that will host the section contents.
 */
ViewPager mViewPager;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_rhino68_panel);

    // Set up the action bar.
    final ActionBar actionBar = getActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

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

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

    // When swiping between different sections, select the corresponding
    // tab. We can also use ActionBar.Tab#select() to do this if we have
    // a reference to the Tab.
    mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            actionBar.setSelectedNavigationItem(position);
        }
    });

    // 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));
    }
}

@Override
protected void onDestroy() {
    super.onDestroy();
    Network.cancelRequests(Rhino68PanelActivity.this);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.rhino68_panel, menu);
    return true;
}   

@Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    // When the given tab is selected, switch to the corresponding page in
    // the ViewPager.
    mViewPager.setCurrentItem(tab.getPosition());
}

@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}

@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
}

/**
 * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
 * one of the sections/tabs/pages.
 */
public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
        // getItem is called to instantiate the fragment for the given page.
        Fragment fragment = null;

        switch (position) {
        case 0: {
            fragment = new OneSectionFragment();
        }
            break;
        case 1: {
            fragment = new TwoSectionFragment();
        }
            break;
        case 2: {
            fragment = new ThreeSectionFragment();
        }
            break;
        default: {
            fragment = new OneSectionFragment();
        }
        }
        return fragment;
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        Locale l = Locale.getDefault();
        switch (position) {
        case 0:
            return "1";
        case 1:
            "2";
        case 2:
            "3";
        }
        return null;
    }
}

public static class oneSectionFragment extends Fragment {


    private static Context mContext;

    public StatusSectionFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_rhino68_panel_status, container, false);
        mContext = getActivity();
        // update view
        ....
        return rootView;
    }
    //fucntions and methods
}

    public static class twoSectionFragment extends Fragment {


    private static Context mContext;

    public StatusSectionFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_rhino68_panel_status, container, false);
        mContext = getActivity();
        // update view
        ....
        return rootView;
    }
    //fucntions and methods
}

现在我注意到一些奇怪的东西，我不确定它是否如何运作或者我做错了什么。

我在每个sectionfragments onCreateView()中设置了一个断点，现在取决于我在标签之间导航的方式，断点是否被击中。

案例1：如果我从选项卡1开始，然后导航到选项卡2 - 没有命中断点如果我然后回到标签1 - 再次没有打破断点

案例2：如果我从选项卡1开始，然后导航到选项卡2 - 没有命中断点如果我然后转到标签3 - 标签3中的断点被击中，如果我再回到2 - 没有断点如果我然后去1 - 标签1断点被击中

当您单击选项卡号2时，它似乎加载了标签号3。现在这是标签管理器的属性吗？或者我的标签管理员只认为有2个标签？

我的意思是运行代码，当选项卡实际进入视图时必须获得更新？

Answer 1

尝试使用：

mViewPager.setOffscreenPageLimit(x);

此方法设置应在空闲状态下保留到视图层次结构中当前页面任一侧的页数。此设置默认为1。 http://developer.android.com/reference/android/support/v4/view/ViewPager.html#setOffscreenPageLimit(int)

Android标签监听器在后台保持2个标签活动

1 个答案: