Java Android-动态负载片段（ViewPager）

Question

In settngs existed checkbox, if it is checked, then a specific fragment must not be loaded. I have just 4 fragment and I use FragmentStatePagerAdapter to show them.

public class TabPagerAdapter extends FragmentStatePagerAdapter {

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

  @Override
  public Fragment getItem(int i) {
    switch (i) {
        case 0:
            return new Fragment_One();
        case 1:
            return new Fragment_Two();
        case 2:
            return new Fragment_Three();
        case 3:
            return new Fragment_Four();
        }
    return null;
  }

  @Override
  public int getCount() {
  return 4;
  }

}

As show fragments, which are not only check in the settings? I get value (true of false (Check or Uncheck) fragment, but how do not show this fragment, i dont know.

Answer 1

You have to adapt your getItem() method as well as the getCount() method.

Let's assume you have a method shouldShowFragment(int fragmentNumber) that tells me for a given fragment number from 0 to 3, whether it should be shown or not (depending on the settings).

Now, implement getCount() like so to return the number of fragments that should be shown:

public int getCount() {
    int cnt = 0;
    for (int i = 0; i < 4; i++) {
        if (shouldShowFragment(i)) cnt++;
    }
    return cnt;
}

And implement getItem() like so to take the not showing fragments into account:

public Fragment getItem(int position) {
    int cnt = -1;     
    for (int i = 0; i < 4; i++) {
        if (shouldShowFragment(i)) cnt++;
        if (cnt == position) {
            switch(i) {
                case 0 : return new Fragment_One();
                case 1 : return new Fragment_Two();
                case 2 : return new Fragment_Three();
                case 3 : return new Fragment_Four();
            }
        }
    }
    return null;
}

Answer 2

First of all Save the all check buttons state globally(ie in shared preferences like btn1.setChecked == true/false whatever) and in above code do like below:-

   @Override
  public Fragment getItem(int i) {
    switch (i) {
        case 0:
            if(btn0.isChecked == true)
            return new Fragment_One();
        case 1:
           if(btn1.isChecked == true)
            return new Fragment_Two();
        case 2:
           if(btn2.isChecked == true)
            return new Fragment_Three();
        case 3:
           if(btn3.isChecked == true)
            return new Fragment_Four();
        }
    return null;
  }