如何通过单击选项卡1中的按钮切换到选项卡2？

Question

I have three tabs, a list on the fragment in tab 1, I want to sent the position of the item I click to fragment two in tab 2 and have the viewpager switch to tab2. I am using an interface to sent the position to the main activity which works fine, invoking a method in fragment two passing it the position is returning a null pointer exception and viewpager is not switching.

The method in MainActivity

@Override
public void respond(int i) {
    Toast.makeText(MainActivity.this,"INSIDE MAINACTIVITY AND i = "+i,Toast.LENGTH_SHORT).show();
    try {
       Bundle args = new Bundle();
        args.putInt("chapters",i);
        PhpFragment f2 = new PhpFragment();
        f2.setArguments(args);
        actionBar = getActionBar();
        actionBar.setSelectedNavigationItem(1);
        viewPager.setCurrentItem(1);

    }catch (Exception ex){
        Toast.makeText(MainActivity.this,"Error from MAIN = "+ ex.toString(),Toast.LENGTH_LONG).show();
    }
}

My FragmentPagerAdapter

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

    @Override
    public Fragment getItem(int i) {
        switch (i){
            case 0:
                return  new JavaFragment();
            case 1:
                    return new PhpFragment();
            case 2:
                return new NetFragment();
        }
        return null;
    }

    @Override
    public int getCount() {
        return 3;
    }
}

Answer 1

If i follow your question... Than you should look into it.

fragments communication in view pager

Or another trick is ..

You're using ViewPager and you can take advantage of it. You can add a tag to a ViewPager like this:

Activity:

pager.setTag("some text");  // pager is a ViewPager object

Then you can get this data via ViewGroup in a fragment like this:

Fragment:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view =  inflater.inflate(R.layout.fragment_main, container, false);

    String result = container.getTag().toString();
    // do something with the result

    return view;

You can also setTag() to the container in the fragment.

Another solution (not mentioned here so far) is sending data through SharedPreferences, but I would suggest using tags if possible.