我想用Kotlin创建一个Android项目，所以我用kotlin和Databinding构建它。没错。但是，当我使用Kotlin Android扩展程序或Butterknife时，无法正常使用从该项目构建的应用程序。
这是我的片段类
class MainFragment: Fragment() {
private var stock: StockQuote? = null
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View {
val binding: FragmentMainBinding = DataBindingUtil.inflate(inflater!!, R.layout.fragment_main, container, false)
binding.stock = stock
search_et.setOnFocusChangeListener { v, hasFocus ->
if(!hasFocus){
val newStock = ScrapingUtil.getQuote(search_et?.text.toString())
if(newStock != null){
stock?.name = newStock.name
}
}
}
return binding.root
}
}
我最初尝试使用Butterknife，但没有成功，我要绑定的View为null。然后我尝试使用Kotlin Android扩展，它在运行时引发了错误
E/AndroidRuntime: FATAL EXCEPTION: main
Process: cn.mister.stockcalculator, PID: 30010
java.lang.RuntimeException: Unable to start activity ComponentInfo{cn.mister.stockcalculator/cn.mister.stockcalculator.MainActivity}: android.view.InflateException: Binary XML file line #10: Binary XML file line #10: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2736)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2807)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1604)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:191)
at android.app.ActivityThread.main(ActivityThread.java:6016)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:821)
Caused by: android.view.InflateException: Binary XML file line #10: Binary XML file line #10: Error inflating class fragment
at android.view.LayoutInflater.inflate(LayoutInflater.java:539)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139)
at cn.mister.stockcalculator.MainActivity.onCreate(MainActivity.kt:10)
at android.app.Activity.performCreate(Activity.java:6370)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1122)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2689)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2807)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1604)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:191)
at android.app.ActivityThread.main(ActivityThread.java:6016)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:821)
Caused by: android.view.InflateException: Binary XML file line #10: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:782)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:835)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139)
at cn.mister.stockcalculator.MainActivity.onCreate(MainActivity.kt:10)
at android.app.Activity.performCreate(Activity.java:6370)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1122)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2689)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2807)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1604)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:191)
at android.app.ActivityThread.main(ActivityThread.java:6016)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:821)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.EditText.setOnFocusChangeListener(android.view.View$OnFocusChangeListener)' on a null object reference
at cn.mister.stockcalculator.MainFragment.onCreateView(MainFragment.kt:23)
at android.app.Fragment.performCreateView(Fragment.java:2236)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:962)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1139)
at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1241)
at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2236)
at android.app.FragmentController.onCreateView(FragmentController.java:98)
at android.app.Activity.onCreateView(Activity.java:5678)
at android.support.v4.app.BaseFragmentActivityApi14.onCreateView(BaseFragmentActivityApi14.java:41)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:68)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:754)
我该如何解决？
答案 0 :(得分：0)
我在Kotlin Android Extensions and Fragments找到了答案。
数据绑定无关紧要，您应该使用search_et方法直接访问onViewCreated