當選擇的項目視圖爲空時，Kotlin在Android上崩潰

Question

我遇到錯誤，並且應用程序在我運行時死亡。

這是錯誤：

07-22 21:02:19.785 3136-3136/? E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering 
07-22 21:02:19.825 3136-3136/? E/dalvikvm: Could not find class 'android.widget.ThemedSpinnerAdapter', referenced from method android.support.v7.widget.AppCompatSpinner$DropDownAdapter.<init> 
07-22 21:02:19.915 3136-3136/? E/AndroidRuntime: FATAL EXCEPTION: main 
    Process: com.example.vankhanhpr.vidu2, PID: 3136 
    java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter selectedItemView 
    at com.example.vankhanhpr.vidu2.fragment_main.fragment_mom_baby.Create_File_Mon$onCreate$1.onItemSelected(Create_File_Mon.kt) 
    at android.widget.AdapterView.fireOnSelected(AdapterView.java:893) 
    at android.widget.AdapterView.selectionChanged(AdapterView.java:880) 
    at android.widget.AdapterView.checkSelectionChanged(AdapterView.java:1043) 
    at android.widget.AdapterView.handleDataChanged(AdapterView.java:1023) 
    at android.widget.AbsSpinner.onMeasure(AbsSpinner.java:180) 
    at android.widget.Spinner.onMeasure(Spinner.java:486) 
    at android.support.v7.widget.AppCompatSpinner.onMeasure(AppCompatSpinner.java:416) 
    at android.view.View.measure(View.java:16628) 
    at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:1231) 
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:590) 
    at android.view.View.measure(View.java:16628) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) 
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) 
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 
    at android.view.View.measure(View.java:16628) 
    at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:719) 
    at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:455) 
    at android.view.View.measure(View.java:16628) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
    at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139) 
    at android.view.View.measure(View.java:16628) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) 
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) 
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 
    at android.view.View.measure(View.java:16628) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
    at android.view.View.measure(View.java:16628) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) 
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) 
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 
    at android.view.View.measure(View.java:16628) 
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
    at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2298) 
    at android.view.View.measure(View.java:16628) 
    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1916) 
    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1113) 
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1295) 
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000) 
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5622) 
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761) 
    at android.view.Choreographer.doCallbacks(Choreographer.java:574) 
    at android.view.Choreographer.doFrame(Choreographer.java:544) 
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747) 
    at android.os.Handler.handleCallback(Handler.java:733) 
    at android.os.Handler.dispatchMessage(Handler.java:95) 
    at android.os.Looper.loop(Looper.java:212) 
    at android.app.ActivityThread.main(ActivityThread.java:5135)[enter image description here][1] 

代碼：

if(flag!!) { 
    var adapter = ArrayAdapter.createFromResource(this, R.array.relationship_arrays, android.R.layout.simple_spinner_item) 
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item) 
    var adapter_sex = ArrayAdapter.createFromResource(this, R.array.sex_arrays, android.R.layout.simple_spinner_item) 
    adapter_sex.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item) 
    relationship_spinner!!.adapter = adapter 
    sex_spinner!!.adapter = adapter_sex 
} 
else 
{ 
    var adapter = ArrayAdapter.createFromResource(this, R.array.relationship_mom, android.R.layout.simple_spinner_item) 
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item) 

    var adapter_sex = ArrayAdapter.createFromResource(this, R.array.sex_mom, android.R.layout.simple_spinner_item) 
    adapter_sex.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item) 

    relationship_spinner!!.adapter = adapter 
    sex_spinner!!.adapter = adapter_sex 
} 

try { 
    relationship_spinner!!.setOnItemSelectedListener(object : OnItemSelectedListener { 
     override fun onItemSelected(parentView: AdapterView<*>, selectedItemView: View, position: Int, id: Long) { 
      relationship = parentView.getItemAtPosition(position).toString() 
     } 

     override fun onNothingSelected(parentView: AdapterView<*>) { 
      var r = 0 
     } 
    }) 

    sex_spinner!!.setOnItemSelectedListener(object : OnItemSelectedListener { 
     override fun onItemSelected(parentView: AdapterView<*>, selectedItemView: View, position: Int, id: Long) { 
      sex = parentView.getItemAtPosition(position).toString() 
     } 

     override fun onNothingSelected(parentView: AdapterView<*>) { 
      var r = 0 
     } 
    }) 
} 
catch (e:Exception){} 

Answer 1

在onItemSelected()，沒有被選中時，selectedItemView參數可以爲null。將其類型更改爲View?而不是View，並正確處理未選擇任何內容的情況。

例（指數也爲負沒有被選中時）：

override fun onItemSelected(parentView: AdapterView<*>, selectedItemView: View?, position: Int, id: Long) { 
        if (position >= 0) { 
          sex = parentView.getItemAtPosition(position).toString() 
        } 
      }