android - Kotlin 失败交付结果
问题描述
在一个Kotlin应用程序中，我们正在尝试将 jpg 文件上传到 ImageView 小部件其他类似的帖子链接
DCIM我们担心的一个问题是通过选择并选择上传上传将图像（jpg）添加到模拟器Device Manager File我们需要DCIM在第一次运行应用程序时导航到这个位置应用程序不知道jpg在哪里。我们将发布 Logcat 代码和 XML 代码
08-29 16:39:27.444 18552-18675/com.androidstackoverflow.habittrainer E/StudioProfiler: JVMTI error: 15(JVMTI_ERROR_THREAD_NOT_ALIVE)
08-29 16:39:27.445 18552-18675/com.androidstackoverflow.habittrainer I/chatty: uid=10084(u0_a84) Binder:18552_3 identical 3 lines
08-29 16:39:27.445 18552-18675/com.androidstackoverflow.habittrainer E/StudioProfiler: JVMTI error: 15(JVMTI_ERROR_THREAD_NOT_ALIVE)
08-29 16:39:28.329 18552-18593/com.androidstackoverflow.habittrainer D/EGL_emulation: eglMakeCurrent: 0xa51c7820: ver 2 0 (tinfo 0xa518b060)
08-29 16:39:28.331 18552-18685/com.androidstackoverflow.habittrainer E/StudioProfiler: JVMTI error: 15(JVMTI_ERROR_THREAD_NOT_ALIVE)
08-29 16:39:28.332 18552-18685/com.androidstackoverflow.habittrainer I/chatty: uid=10084(u0_a84) hwuiTask2 identical 3 lines
08-29 16:39:28.333 18552-18685/com.androidstackoverflow.habittrainer E/StudioProfiler: JVMTI error: 15(JVMTI_ERROR_THREAD_NOT_ALIVE)
08-29 16:39:28.777 18552-18552/com.androidstackoverflow.habittrainer W/View: dispatchProvideAutofillStructure(): not laid out, ignoring
08-29 16:39:28.798 18552-18552/com.androidstackoverflow.habittrainer I/AssistStructure: Flattened final assist data: 3020 bytes, containing 1 windows, 11 views
08-29 16:39:30.252 18552-18552/com.androidstackoverflow.habittrainer I/System.out: =============================== Intent { act=android.intent.action.CHOOSER (has extras) }
08-29 16:39:30.252 18552-18552/com.androidstackoverflow.habittrainer D/CreateHabitActivity: Image was sent
08-29 16:39:30.755 18552-18593/com.androidstackoverflow.habittrainer D/EGL_emulation: eglMakeCurrent: 0xa51c7820: ver 2 0 (tinfo 0xa518b060)
08-29 16:39:30.818 18552-18593/com.androidstackoverflow.habittrainer D/OpenGLRenderer: endAllActiveAnimators on 0x8bfaf980 (RippleDrawable) with handle 0x9957fbf0
08-29 16:39:45.615 18552-18559/com.androidstackoverflow.habittrainer I/zygote: Do partial code cache collection, code=24KB, data=29KB
08-29 16:39:45.618 18552-18559/com.androidstackoverflow.habittrainer I/zygote: After code cache collection, code=24KB, data=29KB
Increasing code cache capacity to 128KB
08-29 16:39:45.622 18552-18552/com.androidstackoverflow.habittrainer D/CreateHabitActivity: An Image WAS Choosen
08-29 16:39:45.623 18552-18552/com.androidstackoverflow.habittrainer I/System.out: ------------------------------ 1 more -1
08-29 16:39:45.661 18552-18552/com.androidstackoverflow.habittrainer D/AndroidRuntime: Shutting down VM
08-29 16:39:45.703 18552-18552/com.androidstackoverflow.habittrainer E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.androidstackoverflow.habittrainer, PID: 18552
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { dat=content://com.android.externalstorage.documents/document/primary:Pictures/water.jpg flg=0x1 }} to activity {com.androidstackoverflow.habittrainer/com.androidstackoverflow.habittrainer.CreateHabitActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageBitmap(android.graphics.Bitmap)' on a null object reference
at android.app.ActivityThread.deliverResults(ActivityThread.java:4324)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:4367)
at android.app.ActivityThread.-wrap19(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1649)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageBitmap(android.graphics.Bitmap)' on a null object reference
at com.androidstackoverflow.habittrainer.CreateHabitActivity.onActivityResult(CreateHabitActivity.kt:71)
at android.app.Activity.dispatchActivityResult(Activity.java:7235)
at android.app.ActivityThread.deliverResults(ActivityThread.java:4320)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:4367)
at android.app.ActivityThread.-wrap19(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1649)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
创建习惯活动文件
class CreateHabitActivity : AppCompatActivity() {
private val TAG = CreateHabitActivity::class.java.simpleName
private val CHOOSE_IMAGE_REQUEST = 1
private var imageBitmap: Bitmap? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
this.setContentView(R.layout.activity_create_habit)
}// end onCreate
fun onstoreHabit(view: View) {
if(etTitle.text.toString().isBlank() &&
etDescription.text.toString().isBlank()) {
Log.d(TAG, "No Image")
displayErrorMsg("You Need TITLE and DESCTIPTIOM")
return
}else if(imageBitmap == null){
displayErrorMsg("Select Image")
Log.d(TAG,"Image Missing")
return
}
tvError.visibility = View.INVISIBLE
}
private fun displayErrorMsg(msg: String) {
tvError.text = msg
tvError.visibility = View.VISIBLE
}
fun onChooseImage(view:View){
val intent = Intent()
intent.type = "image/*"
intent.action = Intent.ACTION_GET_CONTENT
val chooser = Intent.createChooser(intent,"Choose Image for Habit")
startActivityForResult(chooser, CHOOSE_IMAGE_REQUEST)
System.out.println("=============================== "+chooser)
Log .d(TAG,"Image was sent" )
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data:
Intent?) {
super.onActivityResult(requestCode, resultCode, data)
if(requestCode == CHOOSE_IMAGE_REQUEST && resultCode ==
Activity.RESULT_OK
&& data != null && data.data != null){
Log.d(TAG,"An Image WAS Choosen")
System.out.println("------------------------------ "+requestCode+"
more "+resultCode)
// request is 1 and result is -1
val bitmap = tryReadBitmap(data.data)
bitmap?.let {
this.imageBitmap = bitmap
ivIcon.setImageBitmap(bitmap)
// Line of code above on a null object reference
Log.d(TAG,"We Updated and Read Bitmap")
}
}
}
private fun tryReadBitmap(data: Uri?): Bitmap?{
return try{
MediaStore.Images.Media.getBitmap(contentResolver,data)
}catch (e:IOException){
e.printStackTrace()
null
}
}
}// end Class
XML 代码
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/color_lightGray"
android:padding="8dp"
tools:context=".CreateHabitActivity">
<EditText
android:id="@+id/etTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginTop="40dp"
android:layout_weight="1"
android:ems="10"
android:hint="Eat an Apple" />
<EditText
android:id="@+id/etDescription"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginTop="100dp"
android:layout_weight="1"
android:ems="10"
android:hint="Apple a Day No Doctor"
android:inputType="textImeMultiLine"
android:lines="2" />
<Button
android:id="@+id/btnChooseImage"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="160dp"
android:layout_weight="1"
android:onClick="onChooseImage"
android:text="Choose Image"
android:textColor="@color/color_Black"
android:textSize="18sp"
android:textStyle="bold" />
<ImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="220dp"
android:contentDescription="Select Image"
android:padding="10dp" />
<TextView
android:id="@+id/tvError"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginTop="280dp"
android:layout_weight="1"
android:text="Error"
android:visibility="invisible" />
<Button
android:id="@+id/btnSave"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="340dp"
android:layout_weight="1"
android:onClick="onstoreHabit"
android:text="SAVE"
android:textColor="@color/color_Black"
android:textSize="18sp"
android:textStyle="bold" />
</RelativeLayout>
我们的问题是如何使用这行代码 ivIcon.setImageBitmap(bitmap) 修复空对象引用错误
我们已经通过添加和删除进行了测试？这与这行代码
bitmap?.let和这一行data: Intent?）并更改了此声明
private var imageBitmap: Bitmap? = null
这个
System.out.println("------------------------------ "+requestCode+" more "+resultCode)
正在为我们认为不正确的 resultCode 返回 -1
解决方案
正如@jaychang0917 所说，您的 ivIcon 在 XML 文件中不存在，因为它没有名称（id）这两个 ImageView 可以具有相同的 id（名称），正如您所指出的，这里的注意事项是您需要小心您和您从哪里导入。Kotlin 中的这种新行为是不使用 findviewbyid 的权衡
所以是的，您可以在两个单独的 XML 文件中使用相同的 id（名称）
发布此答案是为了澄清 Grendel 的评论 无需投票它是有用的，我们在这里分享和学习
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