相机崩溃时的返回按钮
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【中文标题】相机崩溃时的返回按钮【英文标题】：Back Button on Camera Crashes 【发布时间】：2020-02-13 22:28:17 【问题描述】：我一直在查看 *** 上的各种解决方案，但似乎没有任何效果。我遇到一个问题，当用户启动相机然后按“后退”按钮取消相机时，应用程序崩溃。我认为下面的这段代码可以解决问题，但似乎不起作用。
else if (resultCode== Activity.RESULT_CANCELED)
startActivity(Intent(this, MainActivity::class.java))
println("result cancelled")
return
MainActivity.kt
import android.annotation.SuppressLint
import android.app.Activity
import android.app.AlertDialog
import android.content.Intent
import android.content.pm.ActivityInfo
import android.graphics.Bitmap
import android.graphics.BitmapFactory
import android.media.MediaScannerConnection
import android.os.Bundle
import android.provider.MediaStore
import android.util.Log
import android.view.View
import android.widget.Button
import android.widget.ImageView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.core.graphics.drawable.RoundedBitmapDrawableFactory
import kotlinx.android.synthetic.main.activity_main.*
import java.io.ByteArrayOutputStream
import java.io.File
import java.io.FileOutputStream
import java.io.IOException
import java.util.*
class MainActivity : AppCompatActivity()
private var btn: Button? = null
private var imageview: ImageView? = null
private val GALLERY = 1
private val CAMERA = 2
@SuppressLint("SourceLockedOrientationActivity")
override fun onCreate(savedInstanceState:Bundle?)
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT
btn = findViewById<View>(R.id.btn) as Button
imageview = findViewById<View>(R.id.iv) as ImageView
val wallpaperDirectory = File(getExternalFilesDir(null).toString() + IMAGE_DIRECTORY)
var listImages : Array<File>? = null
listImages = wallpaperDirectory.listFiles()
if(listImages != null && listImages.size!! > 0)
// iv.setImageBitmap(BitmapFactory.decodeFile(listImages[0].absolutePath))
val img2 = BitmapFactory.decodeFile(listImages[0].absolutePath)
val round = RoundedBitmapDrawableFactory.create(resources, img2)
round.isCircular = true
iv.setImageDrawable(round)
else
val img = BitmapFactory.decodeResource(resources, R.mipmap.profile_image)
val round = RoundedBitmapDrawableFactory.create(resources, img)
round.isCircular = true
iv.setImageDrawable(round)
println("hit hit hit")
btn!!.setOnClickListener showPictureDialog()
private fun showPictureDialog()
val pictureDialog = AlertDialog.Builder(this)
pictureDialog.setTitle("Select Action")
val pictureDialogItems = arrayOf("Select Photo From Gallery", "Capture Photo From Camera")
pictureDialog.setItems(pictureDialogItems
) dialog, which ->
when (which)
0 -> choosePhotoFromGallary()
1 -> takePhotoFromCamera()
pictureDialog.show()
fun choosePhotoFromGallary()
val galleryIntent = Intent(Intent.ACTION_PICK,
MediaStore.Images.Media.EXTERNAL_CONTENT_URI)
startActivityForResult(galleryIntent, GALLERY)
fun takePhotoFromCamera()
val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
startActivityForResult(intent, CAMERA)
public override fun onActivityResult(requestCode:Int, resultCode:Int, data: Intent?)
super.onActivityResult(requestCode, resultCode, data)
if (requestCode == GALLERY)
if (data != null)
val contentURI = data.data
try
val bitmap = MediaStore.Images.Media.getBitmap(this.contentResolver, contentURI)
val round = RoundedBitmapDrawableFactory.create(resources, bitmap)
round.isCircular = true
val path = saveImage(bitmap)
Toast.makeText(this@MainActivity, "Image Saved!", Toast.LENGTH_SHORT).show()
imageview!!.setImageDrawable(round)
catch (e: IOException)
e.printStackTrace()
Toast.makeText(this@MainActivity, "Failed!", Toast.LENGTH_SHORT).show()
else if (requestCode == CAMERA)
val thumbnail = data!!.extras!!.get("data") as Bitmap
val round = RoundedBitmapDrawableFactory.create(resources, thumbnail)
round.isCircular = true
imageview!!.setImageDrawable(round)
saveImage(thumbnail)
Toast.makeText(this@MainActivity, "Image Saved!", Toast.LENGTH_SHORT).show()
else if (resultCode== Activity.RESULT_CANCELED)
startActivity(Intent(this, MainActivity::class.java))
println("result cancelled")
fun saveImage(myBitmap: Bitmap):String
val bytes = ByteArrayOutputStream()
myBitmap.compress(Bitmap.CompressFormat.JPEG, 90, bytes)
val wallpaperDirectory = File(getExternalFilesDir(null).toString() + IMAGE_DIRECTORY)
wallpaperDirectory.deleteRecursively()
// have the object build the directory structure, if needed.
Log.d("fee",wallpaperDirectory.toString())
if (!wallpaperDirectory.exists())
wallpaperDirectory.mkdirs()
try
Log.d("heel",wallpaperDirectory.toString())
val f = File(wallpaperDirectory, ((Calendar.getInstance()
.getTimeInMillis()).toString() + ".jpg"))
f.createNewFile()
val fo = FileOutputStream(f)
fo.write(bytes.toByteArray())
MediaScannerConnection.scanFile(this,
arrayOf(f.getPath()),
arrayOf("image/jpeg"), null)
fo.close()
Log.d("TAG", "File Saved::--->" + f.getAbsolutePath())
return f.getAbsolutePath()
catch (e1: IOException)
e1.printStackTrace()
return ""
companion object
private val IMAGE_DIRECTORY = "/demonuts"
acitivity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_
android:layout_
android:orientation="vertical"
android:exported="true"
tools:context=".MainActivity">
<!-- android:text="Select or Capture Image" -->
<Button
android:id="@+id/btn"
android:layout_
android:layout_
android:layout_gravity="center_horizontal"
android:layout_marginTop="40dp"
android:
android:background="#00000000" />
<ImageView
android:id="@+id/iv"
android:layout_
android:layout_
android:layout_gravity="center_horizontal"
android:layout_marginTop="-150dp"
android:scaleType="fitXY"
android:src="@mipmap/profile_image" />
</LinearLayout>
错误日志：
java.lang.RuntimeException: Failure delivering result ResultInfowho=null, request=2, result=0, data=null to activity com.example.pickimagetakeexamples/com.example.pickimagetakeexamples.MainActivity: kotlin.KotlinNullPointerException
at android.app.ActivityThread.deliverResults(ActivityThread.java:4998)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:5041)
at android.app.ActivityThread.access$1600(ActivityThread.java:229)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1875)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:7325)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
Caused by: kotlin.KotlinNullPointerException
at com.example.pickimagetakeexamples.MainActivity.onActivityResult(MainActivity.kt:124)
at android.app.Activity.dispatchActivityResult(Activity.java:7165)
at android.app.ActivityThread.deliverResults(ActivityThread.java:4994)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:5041)
at android.app.ActivityThread.access$1600(ActivityThread.java:229)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1875)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:7325)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
【问题讨论】：
发布堆栈跟踪 你能发布你的错误日志吗？ 请见上文；错误日志已放置。 com.example.pickimagetakeexamples.MainActivity.onActivityResult(MainActivity.kt:124) 处的错误位于 requestCode == Camera 下的 val thumbnal @rengineer 根据您提供的信息，数据似乎为空。 【参考方案1】：根据您的日志，我可以说应用程序崩溃的原因是，您没有捕获图像并且您正在按下返回按钮，该按钮将 null 作为数据返回给您的 onActivityResult，您需要指定如果null 作为结果在您的 onActivityResult 中返回。只需添加默认参数或 if data==null 并处理这种情况。
【讨论】：
【参考方案2】：你应该添加 if 条件。
相机打开，用户返回。使用 resultCode == Activity.RESULT_CANCELED 调用 onActivityResult()。同样，用户从相机拍照。使用 resultCode == Activity.RESULT_OK 调用 onActivityResult。
您在 if 条件中检查了 RequestCode，但没有检查 ResultCode。更改以下 if 条件：
if (Activity.RESULT_OK == resultCode && requestCode == GALLERY)
if (Activity.RESULT_OK == resultCode && requestCode == CAMERA)
【讨论】：
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