使用

   buildFeatures {
        viewBinding=true
    }

这样你就可以是使用了

例如:

• 你的Activity

class MainActivity : AppCompatActivity() {
    lateinit var mainBinding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        mainBinding= ActivityMainBinding.inflate(layoutInflater)
        setContentView(mainBinding.root)
        
    }
}

• 你的fragment

class FragmentOne : Fragment() {
     lateinit var fragmentOneBinding: FragmentOneBinding
    private var param1: String? = null
    private var param2: String? = null
    companion object {
        @JvmStatic
        fun newInstance(param1: String, param2: String) =
            FragmentOne().apply {
                arguments = Bundle().apply {
                    putString(ARG_PARAM1, param1)
                    putString(ARG_PARAM2, param2)
                }
            }
    }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            param1 = it.getString(ARG_PARAM1)
            param2 = it.getString(ARG_PARAM2)
        }
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        fragmentOneBinding= FragmentOneBinding.inflate(layoutInflater,container,false)
        return fragmentOneBinding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        fragmentOneBinding.btnStartFragmentTwo.setOnClickListener {
            it.findNavController().navigate(R.id.action_fragmentOne_to_fragmentTwo)
        }
    }

里面没有findviewbyid 了,这样就避免了null指针异常了

下面我们就开始做一个简单的封装
基类Activity

abstract class BaseActivity<T : ViewBinding> : AppCompatActivity() {
    protected lateinit var viewBinding: T
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
      //  ParameterizedType 表示参数化类型，带有类型参数的类型，即常说的泛型，如：List<T>、Map<Integer, String>、List<? extends Number>。
        val pt = javaClass.genericSuperclass as ParameterizedType
       
        val cla = pt.actualTypeArguments[0] as Class<*>
        try {
           //通过反射加载类的inflate方法
            val declaredMethod = cla.getDeclaredMethod("inflate", LayoutInflater::class.java)
           //通过调用对应方法并强转成T
           viewBinding = declaredMethod.invoke(null, layoutInflater) as T
            setContentView(viewBinding.root)
            initCreate()
        } catch (e: NoSuchMethodException) {
            e.printStackTrace()
        } catch (e: IllegalAccessException) {
            e.printStackTrace()
        } catch (e: InvocationTargetException) {
            e.printStackTrace()
        }
    }

    abstract fun initCreate()
}

基类Fragment

abstract class BaseFragment<T : ViewBinding> : Fragment() {
    protected lateinit var viewBinding: T
    abstract fun initCreateView(savedInstanceState: Bundle?)
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        try {
            //  ParameterizedType 表示参数化类型，带有类型参数的类型，即常说的泛型，如：List<T>、Map<Integer, String>、List<? extends Number>。
            val parameterizedType = javaClass.genericSuperclass as ParameterizedType
            val clazz = parameterizedType.actualTypeArguments[0] as Class<*>
            //通过反射加载类的inflate方法
            val declaredMethod = clazz.getDeclaredMethod("inflate", LayoutInflater::class.java,ViewGroup::class.java,Boolean::class.java)
            //通过调用对应方法并强转成T
            viewBinding = declaredMethod.invoke(null, inflater,container,false) as T
        } catch (e: NoSuchMethodException) {
            e.printStackTrace()
        } catch (e: IllegalAccessException) {
            e.printStackTrace()
        } catch (e: InvocationTargetException) {
            e.printStackTrace()
        }
        return viewBinding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        initCreateView(savedInstanceState)
    }

}

案例:

class TestActivity : BaseActivity<ActivityTestBinding>() {
    override fun initCreate() {
        viewBinding.tvContent.setOnClickListener {
              Toast.makeText(this@TestActivity,"${viewBinding.tvContent.text}",Toast.LENGTH_SHORT).show()
        }
    }
}

class TestFragment : BaseFragment<FragmentTestBinding>() {
    private var param1: String? = null
    private var param2: String? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            param1 = it.getString(ARG_PARAM1)
            param2 = it.getString(ARG_PARAM2)
        }
    }
    companion object {

        @JvmStatic
        fun newInstance(param1: String, param2: String) =
            TestFragment().apply {
                arguments = Bundle().apply {
                    putString(ARG_PARAM1, param1)
                    putString(ARG_PARAM2, param2)
                }
            }
    }

    override fun initCreateView(savedInstanceState: Bundle?) {
        viewBinding.tvTest.setOnClickListener {
              Toast.makeText(activity,"${viewBinding.tvTest.text}",Toast.LENGTH_SHORT).show()
        }
    }
}

这样看是不是简化好多