Kotlin学习笔记——TabLayout

#define 小毛驴 xml

使用场景

如果想让ViewPager的tab标签和Toolbar合二为一的话，可以在Toolbar中嵌套TabLayout

使用方法

1. 编写好小毛驴文件，把TabLayout嵌套到Toolbar中，编写好每一页的小毛驴布局文件，写好传递数据的类
2. 编写Fragment

   class BlankFragment : Fragment() {
       var ctx:Context? = null
       var mPosition:Int = 0
       var mInageId:Int = 0
       var mDesc:String = ""
       var title:String = ""
   
       override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
           ctx = activity
           if (arguments != null) {
               mPosition = arguments!!.getInt("position", 0)
               mInageId = arguments!!.getInt("image_id", 0)
               mDesc = arguments!!.getString("desc")
               title = arguments!!.getString("title")
           }
           val view = inflater.inflate(R.layout.item, container, false)
   
           val pic:ImageView = view.findViewById(R.id.imageView)
           val desc:TextView = view.findViewById(R.id.textView)
   
           pic.setImageResource(mInageId)
           desc.text = mDesc
           return view
       }
   
       companion object {
           fun newInstance(position:Int, image_id:Int, desc:String, title:String) : BlankFragment {
               val fragment = BlankFragment()
               val bundle = Bundle()
               bundle.putInt("position", position)
               bundle.putInt("image_id", image_id)
               bundle.putString("desc", desc)
               bundle.putString("title", title)
               fragment.arguments = bundle
               return fragment
           }
       }
   }

3. 编写ViewPager的适配器

   class infoPagerAdapter(val fragManger: FragmentManager, val itemList:MutableList<itemInfo>) : FragmentStatePagerAdapter(fragManger) {
       override fun getCount(): Int = itemList.size
       override fun getItem(p0: Int): Fragment {
           val item = itemList[p0]
           return BlankFragment.newInstance(p0, item.pic, item.desc, item.name)
       }
   
       override fun getPageTitle(position: Int): CharSequence? {
           return itemList[position].name
       }
   }

4. 给ViewPager添加适配器

   class the_pics : AppCompatActivity() , TabLayout.OnTabSelectedListener {
   
       override fun onTabReselected(p0: TabLayout.Tab?) {}
   
       override fun onTabUnselected(p0: TabLayout.Tab?) {
   
       }
   
       override fun onTabSelected(p0: TabLayout.Tab?) {
           if (p0 != null)
               vp.currentItem = p0.position
               //如果用户点击了某个标签，把下面ViewPager也滚动到相应位置
               //以上三个重载函数都是Toolbar上的标签产生事件后相应的操作
       }
   
       override fun onCreate(savedInstanceState: Bundle?) {
           super.onCreate(savedInstanceState)
           setContentView(R.layout.activity_the_pics)
           val bar:android.support.v7.widget.Toolbar = findViewById(R.id.bar)
           setSupportActionBar(bar)
           supportActionBar?.title = ""
           bar.setNavigationOnClickListener {
               setResult(Activity.RESULT_OK)
               finish()
           }//设置Toolbar的返回导航键的click监听器
   
           var data:MutableList<itemInfo> = mutableListOf()
           /*省略data的赋值过程*/
   
           tab_title.addOnTabSelectedListener(this)
           vp.adapter = infoPagerAdapter(supportFragmentManager, data)
   
           vp.addOnPageChangeListener(object : ViewPager.SimpleOnPageChangeListener() {
               override fun onPageSelected(position: Int) {
                   tab_title.getTabAt(position)!!.select()//让标签栏的第position个变成被选择状态
                   //这个重载函数是ViewPager上有Page的改变后调用的函数
               }
           })
       }
   }