我使用TabLayout切换片段。它在大多数情况下都是有效的，除了当我试图以编程方式使用tab.select()，我的TabLayout选择一个选项卡时。OnTabSelectedListener将触发onTabSelected(TabLayout。Tab Tab)，这会让我很伤心。我正在寻找一种不触发侦听器的方法来做程序化选择。

So I adapted @kenodoggy 's answer to my use. I was further facing a problem where some of the internal objects would return null (because they weren't created yet, because I was answering onActivityResult() from my fragment, which occurs before onCreate() in the case the activity is singleTask or singleInstance) so I wrote up a detailed if/else sequence which would report the error and fall through without the NullPointerException that would otherwise trigger. I use Timber for logging, if you're not using that substitute with Log.e().

void updateSelectedTabTo(int position) {
    if (tabLayout != null){
        int selected = tabLayout.getSelectedTabPosition();
        if (selected != -1){
            TabLayout.Tab oldTab = tabLayout.getTabAt(0);
            if (oldTab != null){
                View view = oldTab.getCustomView();
                if (view != null){
                    view.setSelected(false);
                }
                else {
                    Timber.e("oldTab customView is null");
                }
            }
            else {
                Timber.e("oldTab is null");
            }
        }
        else {
            Timber.e("selected is -1");
        }
        TabLayout.Tab newTab = tabLayout.getTabAt(position);
        if (newTab != null){
            View view = newTab.getCustomView();
            if (view != null){
                view.setSelected(false);
            }
            else {
                Timber.e("newTab customView is null");
            }
        }
        else {
            Timber.e("newTab is null");
        }
    }
    else {
        Timber.e("tablayout is null");
    }
}

这里，tabLayout是绑定到XML中的tabLayout对象的内存变量。我不使用滚动标签功能，所以我把它也删除了。

对于材质组件库提供的TabLayout，只需使用selectTab方法:

TabLayout tabLayout = findViewById(R.id.tab_layout);
tabLayout.selectTab(tabLayout.getTabAt(index));

它需要版本为1.1.0。

我使用TabLayout切换片段。它在大多数情况下都是有效的，除了当我试图以编程方式使用tab.select()，我的TabLayout选择一个选项卡时。OnTabSelectedListener将触发onTabSelected(TabLayout。Tab Tab)，这会让我很伤心。我正在寻找一种不触发侦听器的方法来做程序化选择。

So I adapted @kenodoggy 's answer to my use. I was further facing a problem where some of the internal objects would return null (because they weren't created yet, because I was answering onActivityResult() from my fragment, which occurs before onCreate() in the case the activity is singleTask or singleInstance) so I wrote up a detailed if/else sequence which would report the error and fall through without the NullPointerException that would otherwise trigger. I use Timber for logging, if you're not using that substitute with Log.e().

void updateSelectedTabTo(int position) {
    if (tabLayout != null){
        int selected = tabLayout.getSelectedTabPosition();
        if (selected != -1){
            TabLayout.Tab oldTab = tabLayout.getTabAt(0);
            if (oldTab != null){
                View view = oldTab.getCustomView();
                if (view != null){
                    view.setSelected(false);
                }
                else {
                    Timber.e("oldTab customView is null");
                }
            }
            else {
                Timber.e("oldTab is null");
            }
        }
        else {
            Timber.e("selected is -1");
        }
        TabLayout.Tab newTab = tabLayout.getTabAt(position);
        if (newTab != null){
            View view = newTab.getCustomView();
            if (view != null){
                view.setSelected(false);
            }
            else {
                Timber.e("newTab customView is null");
            }
        }
        else {
            Timber.e("newTab is null");
        }
    }
    else {
        Timber.e("tablayout is null");
    }
}

这里，tabLayout是绑定到XML中的tabLayout对象的内存变量。我不使用滚动标签功能，所以我把它也删除了。

如果你知道你想要选择的标签的索引，你可以这样做:

TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
TabLayout.Tab tab = tabLayout.getTabAt(someIndex);
tab.select();

即使你使用TabLayout本身而没有ViewPager(这是非典型的，可能是不好的做法，但我见过这样做)，这种技术也是有效的。

这也有帮助

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    @Override
    public void onPageScrolled(int i, float v, int i1) {
    }

    @Override
    public void onPageSelected(int i) {
        tablayout.getTabAt(i).select();
    }

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

这将不工作的应用程序，有ViewPager2实现，为此，你需要使用

viewPager2.setCurrentItem(position);

当我们使用TabLayoutMediator时，在onConfigureTab中找到onConfigureTab

i.e

TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(
                tabLayout, viewPager2, new TabLayoutMediator.TabConfigurationStrategy() {
            @Override
            public void onConfigureTab(@NonNull TabLayout.Tab tab, int position) {
                switch (position){
                    case 0 : tab.setIcon(getResources().getDrawable(R.drawable.camera));
                            break;
                    case 1 : tab.setText("CHAT");
                            viewPager2.setCurrentItem(position); // when app starts this will be the selected tab
                            break;
                    case 2 : tab.setText("STATUS");
                            break;
                    case 3 : tab.setText("CALL");
                        break;
                }
            }
        }
        );
        tabLayoutMediator.attach();