Tablayout 标题不出现

Posted 2023-04-18

【中文标题】Tablayout 标题不出现

【英文标题】：Tablayout Title doesn't appear

【发布时间】：2021-08-31 11:09:05

【问题描述】：

我有一个 Tablayout 通过 ViewPager 和适配器显示三个片段，问题是标题没有出现： MainActivity.java：

package com.asd.tab3;

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;

import com.google.android.material.tabs.TabLayout;

public class MainActivity extends AppCompatActivity 
TabLayout tb;
ViewPager vp;
    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tb=findViewById(R.id.tab1);
        vp=findViewById(R.id.viwp);
        final MyAdapter adapter = new MyAdapter(this,getSupportFragmentManager(), tb.getTabCount());
        vp.setAdapter(adapter);
       tb.setupWithViewPager(vp);
    

MyAdapter.java

package com.asd.tab3;
import android.content.Context;

import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentPagerAdapter;

public class MyAdapter extends FragmentPagerAdapter 

    private Context myContext;
    int totalTabs;

    public MyAdapter(Context context, FragmentManager fm, int totalTabs) 
        super(fm);
        myContext = context;
        this.totalTabs = totalTabs;
    

    // this is for fragment tabs
    @Override
    public Fragment getItem(int position) 
        switch (position) 
            case 0:
                BlankFragment homeFragment = new BlankFragment();
                return homeFragment;
            case 1:
                BlankFragment2 sportFragment = new BlankFragment2();
                return sportFragment;
            case 2:
                BlankFragment3 movieFragment = new BlankFragment3();
                return movieFragment;
            default:
                return null;
        
    
    // this counts total number of tabs
    @Override
    public int getCount() 
        return totalTabs;
    

Rem：我的问题和这个帖子不一样：(Titles in TabLayout donsen't appear)

【问题讨论】：

public int getCount() return totalTabs.size();

【参考方案1】：

您应该在 FragmentPageAdapter 类中覆盖方法 getPageTitle()（在您的情况下为 MyAdapter）。

 * This method may be called by the ViewPager to obtain a title string
 * to describe the specified page. This method may return null
 * indicating no title for this page. The default implementation returns
 * null.
 *
 * @param position The position of the title requested
 * @return A title for the requested page

  fun getPageTitle(position: Int): CharSequence?

目前，title 没有出现，因为它使用的是方法的默认实现，总是返回 null。

【参考方案2】：

我通过使用 (getTabAt(index).setText = "Some Text";) 解决了它

 tb.getTabAt(0).setText("First");