刷新/重新加载/重新实例化android选项卡系统中的片段

Question

我有一个带有viewpager的活动,它有3个标签和3个片段,每个标签内都有一个片段.我知道片段管理器存储了片段的初始实例,因此如果我从选项卡上滑动然后返回到该选项卡,它将被加载到内存中,并且不会对其应用任何更新.

我需要发生相反的情况,即:每次我滑动到选项卡时,需要加载该选项卡中的片段的新实例,以便更新数据.

我试过了:

1. 在onTabSelected中分离附加片段(没有任何反应)
2. 删除onTabSelected中的添加片段(没有任何反应)
3. setOffscreenPageLimit(0)(没有任何反应)
4. 刷新每个片段内的函数,调用onTabSelected(给出nullPointerException)

我一直在努力解决这个问题一个星期没有进展.我感谢任何帮助,无论是暗示,评论,建议.

让我知道我应该发布什么代码,谢谢.

Answer 1

我知道答案很老,但是......我找到了解决方案.我不知道它是否是最好的,但在我的情况下,已经解决了.

在活动中:

@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());


        if (tab.getPosition() == 0) {

            LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(this);
            Intent i = new Intent("TAG_REFRESH");
            lbm.sendBroadcast(i);

        }

}

而你的碎片:

public class MyFragment extends Fragment {

MyReceiver r;
public void refresh() {
    //yout code in refresh.
    Log.i("Refresh", "YES");
}

public void onPause() {
    super.onPause();
    LocalBroadcastManager.getInstance(context).unregisterReceiver(r);
}

public void onResume() {
    super.onResume();
    r = new MyReceiver();
    LocalBroadcastManager.getInstance(context).registerReceiver(r,
            new IntentFilter("TAG_REFRESH"));
}

private class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        MyFragment.this.refresh();
    }
}

Answer 2

我会使用类似于以下内容的东西：

public class MainActivity extends FragmentActivity implements ActionBar.TabListener {

    private ViewPager ViewPager;
    private TabsPagerAdapter SectionsPagerAdapter;
    private ActionBar actionBar;

    private String[] tabs = { "Event Details", "Line-up", "Donations", };

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

     // Initialisation
        ViewPager = (ViewPager) findViewById(R.id.pager);
        actionBar = getActionBar();
        SectionsPagerAdapter = new TabsPagerAdapter(getSupportFragmentManager());

        ViewPager.setAdapter(SectionsPagerAdapter);
        actionBar.setHomeButtonEnabled(false);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); 

     // Adding Tabs
        for (String tab_name : tabs) {
            actionBar.addTab(actionBar.newTab().setText(tab_name).setTabListener(this));
        }

        ViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

            @Override
            public void onPageSelected(int position) {
                // on changing the page
                // make respected tab selected
                actionBar.setSelectedNavigationItem(position);
            }

            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {
            }

            @Override
            public void onPageScrollStateChanged(int arg0) {
            }
        });
    }

    @Override
    public void onTabReselected(Tab tab, android.app.FragmentTransaction ft) {

    }

    @Override
    public void onTabSelected(Tab tab, android.app.FragmentTransaction ft) {
        ViewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(Tab tab, android.app.FragmentTransaction ft) {

    }

//Attaching the fragments to the tabPagerAdapter
public class TabsPagerAdapter extends FragmentPagerAdapter {

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

        @Override
        public Fragment getItem(int index) {

            switch (index) {
            case 0:
                return new EventFragment();
            case 1:
                // Points to the Lineup class
                return new LineupFragment();
            case 2:
                // Points to the 
                return new DonationFragment();
            case 3:

                return new ConcertFragment();
            }

            return null;
        }
@Override
        public int getCount() {
            // get item count - equal to number of tabs
            return 4;
        }
    }

//Add your fragments here

希望这对您有帮助:)