android - 返回android中的上一个选项卡时不显示数据

Question

在我的应用程序中，我使用 ViewPager 显示了 4 个选项卡。

tab1 | tab2 | tab3 | tab4

public class Sports_Swipe extends FragmentActivity implements ActionBar.TabListener {
private ViewPager viewPager;
private Sports_SwipeAdapter mAdapter;
private ActionBarSherlock mSherlock;
private ActionBar actionBar;
// Tab titles
private String[] tabs = { "Tab1", "Tab2", "Tab3", "Tab4", "Tab5"};
 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.sports_swipe);

    // Initilization
    viewPager = (ViewPager) findViewById(R.id.pager);

    mAdapter = new Sports_SwipeAdapter(getSupportFragmentManager()); 
    viewPager.setAdapter(mAdapter);
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);        

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

    }
    /**
     * on swiping the viewpager make respective tab selected
     * */
    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 arg0, FragmentTransaction arg1) {
    // TODO Auto-generated method stub

}

@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
    // TODO Auto-generated method stub
    // show respected fragment view
    viewPager.setCurrentItem(tab.getPosition());

}

@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    // TODO Auto-generated method stub

}
}
///////////////////////////////////////////////////

public class Sports_SwipeAdapter extends FragmentPagerAdapter {

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

@Override
public Fragment getItem(int index) {

    switch (index) {
    case 0:
        // Top Rated fragment activity
        return new Tab1();
    case 1:
        // Games fragment activity
        return new Tab2();
    case 2:
        // Movies fragment activity
        return new Tab3();
    case 3:
        // Games fragment activity
        return new Tab4();

    case 4:
        // Movies fragment activity
        return new Tab5();
    }

    return null;
}

@Override
public int getCount() {
    // get item count - equal to number of tabs
    return 5;
}
}

/////////////////////////////////////
public class Tab1 extends Fragment {

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

        View rootView = inflater.inflate(R.layout.activity_tab1, container, false);
     //Here I get all the fields of Tab1 
}
//I did this for remaining tabs also

我的 Activity 是扩展 FragmentActivity。每当页面加载时，我都会显示 tab1 的数据。现在，如果用户单击 tab2，我将获取数据并显示。现在用户点击 tab3 然后我显示 tab3 的数据。到此为止就好了。现在，当用户返回到 tab1 时，tab1 上的数据不可用。它显示的是空白页面。

我应该如何保存选项卡数据或选项卡状态。

谢谢

Answer 1

你只需要通过使用设置离屏页面限制

setOffscreenPageLimit(int 限制)

设置在空闲状态下 View 层次结构中当前页面任一侧应保留的页面数。

所以用

ViewPager.setOffscreenPageLimit(3);