从图库中选择图像后出现空白屏幕
Blank Screen showing up after Image Selected from Gallery
我正在尝试将图像放入 ImageView，但每当我单击图库中的图片时，应用程序都会显示空白屏幕并关闭。
这个 ImageView 在片段中
public View onCreateView(LayoutInflater inflater, ViewGroup container,
捆绑 savedInstanceState) {
查看 v = inflater.inflate(R.layout.fragment_auction_add, 容器, false);
auction_add_imageViewButton = v.findViewById(R.id.auction_add_imageView_button);
auction_add_imageViewButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
imageSelectAction(v);
}
});
dateTimeAction(v);
return v;
}
private void imageSelectAction(View v) {
auction_add_imageViewButton = v.findViewById(R.id.auction_add_imageView_button);
auction_add_image = v.findViewById(R.id.auction_add_imageView);
choosePicture();
}
private void choosePicture() {
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent, "Select Picture"), SELECT_PICTURE);
}
@Override
public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == Activity.RESULT_OK) {
if (requestCode == SELECT_PICTURE) {
if (data != null && data.getData() != null) {
Uri selectedImageUri = data.getData();
auction_add_image.setImageURI(selectedImageUri);
}
}
}
}
初始声明
public class auction_add extends Fragment {
private static final int SELECT_PICTURE = 10;
private static final int PERMISSION_CODE = 11;
ImageButton auction_add_imageViewButton;
//References to all Auction Add Page EditText
EditText auction_add_itemNameTxt;
EditText auction_add_descriptionTxt;
EditText auction_add_initialPriceTxt;
EditText auction_add_startTimeTxt;
EditText auction_add_endTimeTxt;
//Reference to ImageView
private ImageView auction_add_image;
final Calendar myCalendar = Calendar.getInstance();
非常感谢您的帮助！
编辑：
下面是 Android Studio
的 运行 选项卡上的错误
W/System: A resource failed to call close.
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.projectcrest, PID: 5618
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=242868079, result=-1, data=Intent { dat=content://com.android.providers.media.documents/document/image:31 flg=0x1 }} to activity {com.example.projectcrest/com.example.projectcrest.pages.LandingPage}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageURI(android.net.Uri)' on a null object reference
at android.app.ActivityThread.deliverResults(ActivityThread.java:5015)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:5056)
at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageURI(android.net.Uri)' on a null object reference
at com.example.projectcrest.fragments.auction_add.onActivityResult(auction_add.java:155)
at androidx.fragment.app.FragmentManager.onActivityResult(FragmentManager.java:2905)
at androidx.fragment.app.FragmentManager.onActivityResult(FragmentManager.java:2885)
at androidx.activity.result.ActivityResultRegistry.doDispatch(ActivityResultRegistry.java:377)
at androidx.activity.result.ActivityResultRegistry.dispatchResult(ActivityResultRegistry.java:336)
at androidx.activity.ComponentActivity.onActivityResult(ComponentActivity.java:624)
at androidx.fragment.app.FragmentActivity.onActivityResult(FragmentActivity.java:164)
at android.app.Activity.dispatchActivityResult(Activity.java:8310)
at android.app.ActivityThread.deliverResults(ActivityThread.java:5008)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:5056)
at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
I/Process: Sending signal. PID: 5618 SIG: 9
通过查看异常，似乎由于 NPE（空指针异常），应用程序在第 auction_add_image.setImageURI(selectedImageUri); 行的 #onActivityResult 函数中崩溃。 expection/crash 是因为 auction_add_image 对象具有空值而不是 ImageView。
仔细查看您的代码后，我认为问题是由以下代码引起的：
auction_add_imageViewButton = v.findViewById(R.id.auction_add_imageView_button);
auction_add_imageViewButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
imageSelectAction(v);
}
});
请注意，在 #onClick 函数中，您传递的是要执行 #findViewById 操作的视图 v。这里传递的视图 v 指的是 auction_add_imageViewButton 而不是您在上面捕获的 v。
我建议修改如下代码（只需重命名#onClick 函数中的 v 变量）：
auction_add_imageViewButton = v.findViewById(R.id.auction_add_imageView_button);
auction_add_imageViewButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View buttonView) {
imageSelectAction(v);
}
});
这样可以避免变量名冲突并解决错误。
此外，如果这不能解决您的问题，请检查#findViewById 是否 returning ImageView 而不是 null。如果提供给#findViewById 的 Id 没有出现在屏幕上或视图的子视图中（在其上执行#findViewById），那么#findViewById 将 return 空值。
此外，请检查您是否在代码的任何位置为 auction_add_image 分配了空值。
我正在尝试将图像放入 ImageView，但每当我单击图库中的图片时，应用程序都会显示空白屏幕并关闭。 这个 ImageView 在片段中
public View onCreateView(LayoutInflater inflater, ViewGroup container, 捆绑 savedInstanceState) { 查看 v = inflater.inflate(R.layout.fragment_auction_add, 容器, false);
auction_add_imageViewButton = v.findViewById(R.id.auction_add_imageView_button);
auction_add_imageViewButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
imageSelectAction(v);
}
});
dateTimeAction(v);
return v;
}
private void imageSelectAction(View v) {
auction_add_imageViewButton = v.findViewById(R.id.auction_add_imageView_button);
auction_add_image = v.findViewById(R.id.auction_add_imageView);
choosePicture();
}
private void choosePicture() {
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent, "Select Picture"), SELECT_PICTURE);
}
@Override
public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == Activity.RESULT_OK) {
if (requestCode == SELECT_PICTURE) {
if (data != null && data.getData() != null) {
Uri selectedImageUri = data.getData();
auction_add_image.setImageURI(selectedImageUri);
}
}
}
}
初始声明
public class auction_add extends Fragment {
private static final int SELECT_PICTURE = 10;
private static final int PERMISSION_CODE = 11;
ImageButton auction_add_imageViewButton;
//References to all Auction Add Page EditText
EditText auction_add_itemNameTxt;
EditText auction_add_descriptionTxt;
EditText auction_add_initialPriceTxt;
EditText auction_add_startTimeTxt;
EditText auction_add_endTimeTxt;
//Reference to ImageView
private ImageView auction_add_image;
final Calendar myCalendar = Calendar.getInstance();
非常感谢您的帮助！
编辑：
下面是 Android Studio
的 运行 选项卡上的错误W/System: A resource failed to call close.
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.projectcrest, PID: 5618
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=242868079, result=-1, data=Intent { dat=content://com.android.providers.media.documents/document/image:31 flg=0x1 }} to activity {com.example.projectcrest/com.example.projectcrest.pages.LandingPage}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageURI(android.net.Uri)' on a null object reference
at android.app.ActivityThread.deliverResults(ActivityThread.java:5015)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:5056)
at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageURI(android.net.Uri)' on a null object reference
at com.example.projectcrest.fragments.auction_add.onActivityResult(auction_add.java:155)
at androidx.fragment.app.FragmentManager.onActivityResult(FragmentManager.java:2905)
at androidx.fragment.app.FragmentManager.onActivityResult(FragmentManager.java:2885)
at androidx.activity.result.ActivityResultRegistry.doDispatch(ActivityResultRegistry.java:377)
at androidx.activity.result.ActivityResultRegistry.dispatchResult(ActivityResultRegistry.java:336)
at androidx.activity.ComponentActivity.onActivityResult(ComponentActivity.java:624)
at androidx.fragment.app.FragmentActivity.onActivityResult(FragmentActivity.java:164)
at android.app.Activity.dispatchActivityResult(Activity.java:8310)
at android.app.ActivityThread.deliverResults(ActivityThread.java:5008)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:5056)
at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
I/Process: Sending signal. PID: 5618 SIG: 9
通过查看异常，似乎由于 NPE（空指针异常），应用程序在第 auction_add_image.setImageURI(selectedImageUri); 行的 #onActivityResult 函数中崩溃。 expection/crash 是因为 auction_add_image 对象具有空值而不是 ImageView。
仔细查看您的代码后，我认为问题是由以下代码引起的：
auction_add_imageViewButton = v.findViewById(R.id.auction_add_imageView_button);
auction_add_imageViewButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
imageSelectAction(v);
}
});
请注意，在 #onClick 函数中，您传递的是要执行 #findViewById 操作的视图 v。这里传递的视图 v 指的是 auction_add_imageViewButton 而不是您在上面捕获的 v。
我建议修改如下代码（只需重命名#onClick 函数中的 v 变量）：
auction_add_imageViewButton = v.findViewById(R.id.auction_add_imageView_button);
auction_add_imageViewButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View buttonView) {
imageSelectAction(v);
}
});
这样可以避免变量名冲突并解决错误。
此外，如果这不能解决您的问题，请检查#findViewById 是否 returning ImageView 而不是 null。如果提供给#findViewById 的 Id 没有出现在屏幕上或视图的子视图中（在其上执行#findViewById），那么#findViewById 将 return 空值。
此外，请检查您是否在代码的任何位置为 auction_add_image 分配了空值。