ViewPager滑动正常但手动点击TabLayout标签无响应该如何解决

你目前仅配置了ViewPager滑动时同步TabLayout选中状态的单向关联，缺少点击Tab时同步切换ViewPager页面的逻辑，因此点击Signup标签无响应。无需单独给每个Tab设置onClickListener，按以下两种方案修改即可：

方案1：最小改动（无需修改Adapter） #

仅需在LoginActivity的onCreate方法中补充TabLayout的选中监听，点击Tab时主动切换ViewPager页面：

public class LoginActivity extends AppCompatActivity {

    TabLayout tabLayout;
    ViewPager viewPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        tabLayout = findViewById(R.id.tab_layout);
        viewPager = findViewById(R.id.view_pager);
        
        tabLayout.addTab(tabLayout.newTab().setText("Login"));
        tabLayout.addTab(tabLayout.newTab().setText("Signup"));

        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        final LoginAdapter adapter = new LoginAdapter(getSupportFragmentManager(), this, tabLayout.getTabCount());
        viewPager.setAdapter(adapter);

        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        // 新增：点击Tab时同步切换ViewPager页面
        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) {}
            @Override
            public void onTabReselected(TabLayout.Tab tab) {}
        });
        
        tabLayout.setTranslationY(300);
    }
}

方案2：官方推荐双向绑定写法 #

使用TabLayout自带的setupWithViewPager方法自动实现滑动、点击的双向联动，后续扩展Tab时更规范，需要修改两处代码：

第一步：给LoginAdapter新增getPageTitle方法，返回每个Tab的显示文本 #

public class LoginAdapter extends FragmentPagerAdapter {

    private Context context;
    int totalTabs;

    public LoginAdapter(FragmentManager fa, Context context, int totalTabs) {
        super(fa);
        this.context = context;
        this.totalTabs = totalTabs;
    }

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

    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new LoginTabFragment();
            case 1:
                return new SignupTabFragment();
            default:
                return null;
        }
    }
    
    // 新增：返回Tab的显示文本
    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0: return "Login";
            case 1: return "Signup";
            default: return "";
        }
    }
}

第二步：调整LoginActivity的初始化逻辑，删除手动加Tab和单向监听的代码，调用绑定方法 #

public class LoginActivity extends AppCompatActivity {

    TabLayout tabLayout;
    ViewPager viewPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        tabLayout = findViewById(R.id.tab_layout);
        viewPager = findViewById(R.id.view_pager);
        
        // 删除手动添加Tab的代码，setupWithViewPager会自动创建Tab
        tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

        final LoginAdapter adapter = new LoginAdapter(getSupportFragmentManager(), this, 2);
        viewPager.setAdapter(adapter);

        // 新增：双向绑定，自动处理滑动、点击联动，无需单独设置监听
        tabLayout.setupWithViewPager(viewPager);
        
        tabLayout.setTranslationY(300);
    }
}

内容的提问来源于stack exchange，提问作者Shubham Singh