我addActivity托管了5个片段，在每个片段上我都需要填写一些字段。
我想从中获取这些字段的值addActivity。我尝试了类似的东西：
AddActivity.java

public class AddActivity extends FragmentActivity {
    ViewPager vp;
    ProgressDialog dialog;

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

        vp = (ViewPager) findViewById(R.id.pager);
        PagerAdapter pa = new FragPagerAdapter(getSupportFragmentManager());
        vp.setAdapter(pa);}

    public class getValueOfFields() {
  //here I'm trying to get the value of differents fields in the different fragments but I get

always "editText == Null" If the editText is in The fragment 1 or 2 or 3 it will get null
     EditText editTextFromFrag1 = (EditText) findViewById(R.id.visitDateFiled); // this == null
// If the EditText is in Fragment 4 or 5 it will get the value normaly without any issue


             ...}

FragPagerAdapter.java

public class FragPagerAdapter extends FragmentPagerAdapter {
    public FragPagerAdapter(FragmentManager fm) {
        super(fm);}

    @Override
    public Fragment getItem(int index) {
        switch (index) {
            case 0:
                return new FirstFragment();
            case 1:
                return new SecondFragment();
            case 2:
                return new HousingFragment();
            case 3:
                return new FeedingFragment();
            case 4:
                return new OtherFragment();
        }

        return null;
    }

    @Override
    public int getCount() {
        return 5; }

OtherFragment.java 公共类OtherFragment扩展Fragment {Button btn;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_other, container, false);
    btn = (Button) view.findViewById(R.id.send);
    btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
//Call the getValueOfFields (After filling the differnts fields the user click the send button) 
                ((AddActivity) getActivity()).getValueOfFields();
            }
        });
        return view;
    }
}

更新
的问题我总是得到EditText（而其他字段要获得）的问题等于null如果它们位于片段1或2或3中。否则我得到了正确的值