How to Change Viewpager's Page

How to change ViewPager's page?

I'm not sure that I fully understand the question, but from the title of your question, I'm guessing that what you're looking for is pager.setCurrentItem( num ). That allows you to programatically switch to another page within the ViewPager.

I'd need to see a stack trace from logcat to be more specific if this is not the problem.

ViewPager set current page programmatically

In your PagerActivity use

    viewPager = (ViewPager) findViewById(R.id.view_pager);
    viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            int pagei = position + 1;
            pages=pagei + "";

            Toast.makeText(PagerActivity.this, getString(R.string.changeinfopage) + " " + pages, Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        }

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

and

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        switch (item.getItemId()) {

            case R.id.action_previous:

                viewPager.setCurrentItem(viewPager.getCurrentItem() - 1);
                return true;

            case R.id.action_next:

                viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
                return true;
        }

        return super.onOptionsItemSelected(item);

   }

How to change page in ViewPager Android?

How to change page in ViewPager Android?

Use ViewPager.setCurrentItem(int item) for changing ViewPager pages programmatically.

Where item is index of Page which want to set as current item in ViewPager.

How to change page with button in viewPager?

The DialogFragmentContainer is the parent fragment of the ViewPager page fragments; i.e. it's the parent of Step1 through Step4 fragments.

And therefore you can access it from Step1 fragment, the fragment that you want to change the current ViewPager page using the parentFragment attribute:

binding.btnNext.setOnClickListener{ 
    //I want to change fragment here 
    (parentFragment as DialogFragmentContainer).binding.pager.currentItem = myItemPosition
}

Change page on button click ViewPager Android

you get NPE on line 71 @ MyFragment, as you said in comment this line is:

 mViewPager.setCurrentItem(1, true);

so mViewPager is null, you need initialize that before using

use following code instead your code:

mViewPager.setCurrentItem(getItem(+1), true);

and getItem() is:

private int getItem(int i) {
       return mViewPager.getCurrentItem() + i;
}

Change the page number for viewPager

Here is an example of using dynamic radio button as an indicator in viewpager:
(this example from fragment, so just adjustment for your usage)

final RadioGroup radioGroup = (RadioGroup) rootView.findViewById(R.id.radiogroup);

    final RadioButton[] rb = new RadioButton[items.length];

    for (int i = 0; i < items.length; i++) {
        final int j = i;
        rb[i] = new RadioButton(rootView.getContext());
        radioGroup.addView(rb[i]);
        rb[i].setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                viewPager.setCurrentItem(items.length - j - 1);
            }
        });
    }

How to control ViewPager change page in Fragment object

you can use eventbus notice viewpager to next page.
implement toNextPage func

void toNextPage() {
    if (viewPager.getAdapter().getCount() >= viewPager.getCurrentItem() + 1) {
        viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
    } else {
        Toast.makeText(this, "is end", Toast.LENGTH_SHORT).show();
    }
}

Change viewpager fragment by a buttonClick

I'm not sure what exactly you said about "Change".

If you're asking about change page display index, you can try

ViewPager.setCurrentItem(int pageIndex, boolean isSmoothScroll);

Or, if you're asking about change content, here's what I did

public class MyPagerAdapter extends FragmentStatePagerAdapter
{
  private FragmentManager fragMan;
  private ArrayList<Fragment> fragments=new ArrayList<Fragment>();

  public void clearAll() //You can clear any specified page if you want...
  {
    for(int i=0; i<fragments.size(); i++)
    fragMan.beginTransaction().remove(fragments.get(i)).commit();
    fragments.clear();
    fragments=new ArrayList<Fragment>();
    notifyDataSetChanged();
  }

  public void addList() //Add some new fragment...
  {
    listFrag=new ListFragment();
    fragments.add(list);
  }
}

Hope it helps~

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