当选择的项目视图为空时，Kotlin在Android上崩溃
我得到一个错误，当我运行它的应用程序死亡。
这是错误的：
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] 码：
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){}
在onItemSelected() ，当没有选择任何东西时， selectedItemView参数可以为null。 将其类型更改为View? 而不是View并正确处理没有选择任何东西的情况。
示例（当没有选中时，索引也是负数）：
override fun onItemSelected(parentView: AdapterView<*>, selectedItemView: View?, position: Int, id: Long) { if (position >= 0) { sex = parentView.getItemAtPosition(position).toString() } }