ViewPager2的基本使用就不介绍了, 直接看google官方的ViewPager2搭配TabLayout的使用，主要类是下边这个

/** * A mediator to link a TabLayout with a ViewPager2. The mediator will synchronize the ViewPager2's * position with the selected tab when a tab is selected, and the TabLayout's scroll position when * the user drags the ViewPager2. * * Establish the link by creating an instance of this class, make sure the ViewPager2 has an adapter * and then call {
    @link #attach()} on it. When creating an instance of this class, you must supply * an implementation of {
    @link OnConfigureTabCallback} in which you set the text of the tab, and/or * perform any styling of the tabs that you require. * * @hide */@RestrictTo(LIBRARY_GROUP)public final class TabLayoutMediator {    private final @NonNull TabLayout mTabLayout;    private final @NonNull ViewPager2 mViewPager;    private final boolean mAutoRefresh;    private final OnConfigureTabCallback mOnConfigureTabCallback;    private RecyclerView.Adapter mAdapter;    private boolean mAttached;    private TabLayoutOnPageChangeCallback mOnPageChangeCallback;    private TabLayout.OnTabSelectedListener mOnTabSelectedListener;    private RecyclerView.AdapterDataObserver mPagerAdapterObserver;    /**     * A callback interface that must be implemented to set the text and styling of newly created     * tabs.     */    public interface OnConfigureTabCallback {        /**         * Called to configure the tab for the page at the specified position. Typically calls         * {
    @link TabLayout.Tab#setText(CharSequence)}, but any form of styling can be applied.         *         * @param tab The Tab which should be configured to represent the title of the item at the         *        given position in the data set.         * @param position The position of the item within the adapter's data set.         */        void onConfigureTab(@NonNull TabLayout.Tab tab, int position);    }    /**     * Creates a TabLayoutMediator to synchronize a TabLayout and a ViewPager2 together. It will     * update the tabs automatically when the data set of the view pager's adapter changes. The link     * will be established after {
    @link #attach()} is called.     *     * @param tabLayout The tab bar to link     * @param viewPager The view pager to link     */    public TabLayoutMediator(@NonNull TabLayout tabLayout, @NonNull ViewPager2 viewPager,            @NonNull OnConfigureTabCallback onConfigureTabCallback) {        this(tabLayout, viewPager, true, onConfigureTabCallback);    }    /**     * Creates a TabLayoutMediator to synchronize a TabLayout and a ViewPager2 together. If {
    @code     * autoRefresh} is true, it will update the tabs automatically when the data set of the view     * pager's adapter changes. The link will be established after {
    @link #attach()} is called.     *     * @param tabLayout The tab bar to link     * @param viewPager The view pager to link     * @param autoRefresh If {
    @code true}, will recreate all tabs when the data set of the view     *                   pager's adapter changes.     */    public TabLayoutMediator(@NonNull TabLayout tabLayout, @NonNull ViewPager2 viewPager,            boolean autoRefresh, @NonNull OnConfigureTabCallback onConfigureTabCallback) {        mTabLayout = tabLayout;        mViewPager = viewPager;        mAutoRefresh = autoRefresh;        mOnConfigureTabCallback = onConfigureTabCallback;    }    /**     * Link the TabLayout and the ViewPager2 together.     * @throws IllegalStateException If the mediator is already attached, or the ViewPager2 has no     *         adapter.     */    public void attach() {        if (mAttached) {            throw new IllegalStateException("TabLayoutMediator is already attached");        }        mAdapter = mViewPager.getAdapter();        if (mAdapter == null) {            throw new IllegalStateException("TabLayoutMediator attached before ViewPager2 has an "                    + "adapter");        }        mAttached = true;        // Add our custom OnPageChangeCallback to the ViewPager        mOnPageChangeCallback = new TabLayoutOnPageChangeCallback(mTabLayout);        mViewPager.registerOnPageChangeCallback(mOnPageChangeCallback);        // Now we'll add a tab selected listener to set ViewPager's current item        mOnTabSelectedListener = new ViewPagerOnTabSelectedListener(mViewPager);        mTabLayout.addOnTabSelectedListener(mOnTabSelectedListener);        // Now we'll populate ourselves from the pager adapter, adding an observer if        // autoRefresh is enabled        if (mAutoRefresh) {            // Register our observer on the new adapter            mPagerAdapterObserver = new PagerAdapterObserver();            mAdapter.registerAdapterDataObserver(mPagerAdapterObserver);        }        populateTabsFromPagerAdapter();        // Now update the scroll position to match the ViewPager's current item        mTabLayout.setScrollPosition(mViewPager.getCurrentItem(), 0f, true);    }    /**     * Unlink the TabLayout and the ViewPager     */    public void detach() {        mAdapter.unregisterAdapterDataObserver(mPagerAdapterObserver);        mTabLayout.removeOnTabSelectedListener(mOnTabSelectedListener);        mViewPager.unregisterOnPageChangeCallback(mOnPageChangeCallback);        mPagerAdapterObserver = null;        mOnTabSelectedListener = null;        mOnPageChangeCallback = null;        mAttached = false;    }    @SuppressWarnings("WeakerAccess")    void populateTabsFromPagerAdapter() {        mTabLayout.removeAllTabs();        if (mAdapter != null) {            int adapterCount = mAdapter.getItemCount();            for (int i = 0; i < adapterCount; i++) {                TabLayout.Tab tab = mTabLayout.newTab();                mOnConfigureTabCallback.onConfigureTab(tab, i);                mTabLayout.addTab(tab, false);            }            // Make sure we reflect the currently set ViewPager item            if (adapterCount > 0) {                int currItem = mViewPager.getCurrentItem();                if (currItem != mTabLayout.getSelectedTabPosition()) {                    mTabLayout.getTabAt(currItem).select();                }            }        }    }    /**     * A {
    @link ViewPager2.OnPageChangeCallback} class which contains the necessary calls back to     * the provided {
    @link TabLayout} so that the tab position is kept in sync.     *     * 
This class stores the provided TabLayout weakly, meaning that you can use {
    @link     * ViewPager2#registerOnPageChangeCallback(ViewPager2.OnPageChangeCallback)} without removing     * the callback and not cause a leak.     */    private static class TabLayoutOnPageChangeCallback extends ViewPager2.OnPageChangeCallback {        private final WeakReference
     
       mTabLayoutRef;        private int mPreviousScrollState;        private int mScrollState;        TabLayoutOnPageChangeCallback(TabLayout tabLayout) {            mTabLayoutRef = new WeakReference<>(tabLayout);            reset();        }        @Override        public void onPageScrollStateChanged(final int state) {            mPreviousScrollState = mScrollState;            mScrollState = state;        }        @Override        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {            TabLayout tabLayout = mTabLayoutRef.get();            if (tabLayout != null) {                // Only update the text selection if we're not settling, or we are settling after                // being dragged                boolean updateText = mScrollState != SCROLL_STATE_SETTLING                        || mPreviousScrollState == SCROLL_STATE_DRAGGING;                // Update the indicator if we're not settling after being idle. This is caused                // from a setCurrentItem() call and will be handled by an animation from                // onPageSelected() instead.                boolean updateIndicator = !(mScrollState == SCROLL_STATE_SETTLING                        && mPreviousScrollState == SCROLL_STATE_IDLE);                setScrollPosition(tabLayout, position, positionOffset, updateText, updateIndicator);            }        }        @Override        public void onPageSelected(final int position) {            TabLayout tabLayout = mTabLayoutRef.get();            if (tabLayout != null                    && tabLayout.getSelectedTabPosition() != position                    && position < tabLayout.getTabCount()) {                // Select the tab, only updating the indicator if we're not being dragged/settled                // (since onPageScrolled will handle that).                boolean updateIndicator = mScrollState == SCROLL_STATE_IDLE                        || (mScrollState == SCROLL_STATE_SETTLING                        && mPreviousScrollState == SCROLL_STATE_IDLE);                selectTab(tabLayout, tabLayout.getTabAt(position), updateIndicator);            }        }        void reset() {            mPreviousScrollState = mScrollState = SCROLL_STATE_IDLE;        }    }    // region Reflective calls    // Temporarily call methods TabLayout.setScrollPosition(int, float, boolean, boolean) and    // TabLayout.selectTab(TabLayout.Tab, boolean) through reflection, until they have been made    // public in the Material Design Components library.    private static Method sSetScrollPosition;    private static Method sSelectTab;    private static final String SET_SCROLL_POSITION_NAME = "TabLayout.setScrollPosition(int, float,"            + " boolean, boolean)";    private static final String SELECT_TAB_NAME = "TabLayout.selectTab(TabLayout.Tab, boolean)";    static {        try {            sSetScrollPosition = TabLayout.class.getDeclaredMethod("setScrollPosition", int.class,                    float.class, boolean.class, boolean.class);            sSetScrollPosition.setAccessible(true);            sSelectTab = TabLayout.class.getDeclaredMethod("selectTab", TabLayout.Tab.class,                    boolean.class);            sSelectTab.setAccessible(true);        } catch (NoSuchMethodException e) {            throw new IllegalStateException("Can't reflect into method TabLayout"                    + ".setScrollPosition(int, float, boolean, boolean)");        }    }    @SuppressWarnings("WeakerAccess")    static void setScrollPosition(TabLayout tabLayout, int position, float positionOffset,            boolean updateSelectedText, boolean updateIndicatorPosition) {        try {            if (sSetScrollPosition != null) {                sSetScrollPosition.invoke(tabLayout, position, positionOffset, updateSelectedText,                        updateIndicatorPosition);            } else {                throwMethodNotFound(SET_SCROLL_POSITION_NAME);            }        } catch (Exception e) {            throwInvokeFailed(SET_SCROLL_POSITION_NAME);        }    }    @SuppressWarnings("WeakerAccess")    static void selectTab(TabLayout tabLayout, TabLayout.Tab tab, boolean updateIndicator) {        try {            if (sSelectTab != null) {                sSelectTab.invoke(tabLayout, tab, updateIndicator);            } else {                throwMethodNotFound(SELECT_TAB_NAME);            }        } catch (Exception e) {            throwInvokeFailed(SELECT_TAB_NAME);        }    }    private static void throwMethodNotFound(String method) {        throw new IllegalStateException("Method " + method + " not found");    }    private static void throwInvokeFailed(String method) {        throw new IllegalStateException("Couldn't invoke method " + method);    }    // endregion    /**     * A {
    @link TabLayout.OnTabSelectedListener} class which contains the necessary calls back to     * the provided {
    @link ViewPager2} so that the tab position is kept in sync.     */    private static class ViewPagerOnTabSelectedListener implements TabLayout.OnTabSelectedListener {        private final ViewPager2 mViewPager;        ViewPagerOnTabSelectedListener(ViewPager2 viewPager) {            this.mViewPager = viewPager;        }        @Override        public void onTabSelected(TabLayout.Tab tab) {            mViewPager.setCurrentItem(tab.getPosition(), true);        }        @Override        public void onTabUnselected(TabLayout.Tab tab) {            // No-op        }        @Override        public void onTabReselected(TabLayout.Tab tab) {            // No-op        }    }    private class PagerAdapterObserver extends RecyclerView.AdapterDataObserver {        PagerAdapterObserver() {}        @Override        public void onChanged() {            populateTabsFromPagerAdapter();        }        @Override        public void onItemRangeChanged(int positionStart, int itemCount) {            populateTabsFromPagerAdapter();        }        @Override        public void onItemRangeChanged(int positionStart, int itemCount, @Nullable Object payload) {            populateTabsFromPagerAdapter();        }        @Override        public void onItemRangeInserted(int positionStart, int itemCount) {            populateTabsFromPagerAdapter();        }        @Override        public void onItemRangeRemoved(int positionStart, int itemCount) {            populateTabsFromPagerAdapter();        }        @Override        public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {            populateTabsFromPagerAdapter();        }    }}复制代码
     

有了上边这个类，使用起来就很简单了

override fun onCreate(savedInstanceState: Bundle?) {    super.onCreate(savedInstanceState)    tabLayout = findViewById(R.id.tabs)    viewPager.adapter = adapter    TabLayoutMediator(tabLayout, viewPager) { tab, position ->        tab.text = "tabTitle"    }.attach()}复制代码

ok了，现在TabLayout和ViewPager就可以实现联动了,官方案例地址