如果需要，创建一个接口; FragmentLifecycle { onPauseFragment(); onsumefragment (); ｝ 如所示，在viewpager中的每个片段中实现接口

公共类FragmentCast扩展Fragment实现FragmentLifecycle { @Override onPauseFragment() { 日志。我(标签,“onPauseFragment () "); Toast.makeText(getActivity()， "onPauseFragment():" + TAG, Toast.LENGTH_SHORT).show(); ｝ @Override onResumeFragment() { 日志。我(标签,“onResumeFragment () "); Toast.makeText(getActivity()， "onResumeFragment():" + TAG, Toast.LENGTH_SHORT).show(); ｝

List this is how u user the addOnPageListener enter viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() { int currentPosition = 0; @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { FragmentLifecycle fragmentLifecycleToShow =(FragmentLifecycle) viewPager.getAdapter().instantiateItem(viewPager, viewPager.getCurrentItem()); fragmentLifecycleToShow.onResumeFragment(); FragmentLifecycle fragmentLifecycleToHide =(FragmentLifecycle) viewPager.getAdapter().instantiateItem(viewPager, currentPosition); fragmentLifecycleToHide.onPauseFragment(); currentPosition = position; } @Override public void onPageScrollStateChanged(int state) { } }); Implement your calls in the onPauseFragment() or onResumeFragment()

以防有人需要kotlin中的解决方案:

viewPager.addOnPageChangeListener (object: ViewPager.OnPageChangeListener {
        override fun onPageScrollStateChanged(state: Int) {
            TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
        }

        override fun onPageScrolled(position: Int, positionOffset: Float, positionOffsetPixels: Int) {
            TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
        }

        override fun onPageSelected(position: Int) {
            TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
        }

    })

: viewpage。setOnPageChangeListener现在已弃用。需要使用ViewPager。addOnPageChangeListener代替。

例如,

ViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {

        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
    });

你可以在这里找到这个。

这是新的方法，导航栏与viewpager它为我工作。

binding.viewPager.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                super.onPageScrolled(position, positionOffset, positionOffsetPixels);
            }

            @Override
            public void onPageSelected(int position) {
                super.onPageSelected(position);
                switch (position) {
                    case 0:
                        binding.bottomNavigation.getMenu().findItem(R.id.nav_item_Home).setChecked(true);
                        break;
                    case 1:
                        binding.bottomNavigation.getMenu().findItem(R.id.nav_item_Booking).setChecked(true);
                        break;
                    case 2:
                        binding.bottomNavigation.getMenu().findItem(R.id.nav_item_Transaction).setChecked(true);
                        break;
                    case 3:
                        binding.bottomNavigation.getMenu().findItem(R.id.nav_item_HealthyFood).setChecked(true);
                        break;
                }

            }
        });

你可以通过SimpleOnPageChangeListener来实现 守则如下:

private Fragment page = null;
/** Defining a listener for pageChange */
        ViewPager.SimpleOnPageChangeListener pageChangeListener = new ViewPager.SimpleOnPageChangeListener(){
            @Override
            public void onPageSelected(int position) {
                super.onPageSelected(position);

                page = getSupportFragmentManager().findFragmentByTag("android:switcher:" + R.id.pager_selectPhotos + ":" + position);

                System.out.println(page);
                switch (position) {
                case 0:

                    break;
                case 1:

                    break;

                default:
                    break;
                }
            }
        };
        /** Setting the pageChange listener to the viewPager */
        _pager.setOnPageChangeListener(pageChangeListener);

使用:viewpage。addOnPageChangeListener而不是viewpage . setonpagechangelistener。