Make Android Lifecycle Observer receiver non nullable in Kotlin
I have Result wrapper that wraps data comes from backend
data class Result<T>(val success: Boolean, val result: T?, val message: String?)
Idea of this, check success instead of result being null or not valid and get formatted message for UI error reporting. But when trying to use this with android lifestyle components, specifically in Observer I have to check for null.
How can I avoid this null check? This happens because of
void onChanged(@Nullable T t);
in Observer. I've tried to extend this but it seem to require more custom wrapper classes. Do we have a solution for avoid null check here.
android kotlin android-lifecycle asked Nov 22 '18 at 6:22
Ruwanka MadhushanRuwanka Madhushan
1,64632037
add a comment |
I have Result wrapper that wraps data comes from backend
data class Result<T>(val success: Boolean, val result: T?, val message: String?)
Idea of this, check success instead of result being null or not valid and get formatted message for UI error reporting. But when trying to use this with android lifestyle components, specifically in Observer I have to check for null.
How can I avoid this null check? This happens because of
void onChanged(@Nullable T t);
in Observer. I've tried to extend this but it seem to require more custom wrapper classes. Do we have a solution for avoid null check here.
android kotlin android-lifecycle asked Nov 22 '18 at 6:22
Ruwanka MadhushanRuwanka Madhushan
1,64632037
I think its mostly because the output(Result<Location>?) can be either success or Null. Therefore it is asking you to add a safe operator check to avoid that. So I think it should beit?.successor you can do aletoperator on the result.
– ASN
Nov 22 '18 at 6:35
1
Your right from one perspective, but since we handling the updates ofMutableLiveDatawe can make sure thatnullis not posted as result
– Ruwanka Madhushan
Nov 22 '18 at 6:38
add a comment |
I have Result wrapper that wraps data comes from backend
data class Result<T>(val success: Boolean, val result: T?, val message: String?)
Idea of this, check success instead of result being null or not valid and get formatted message for UI error reporting. But when trying to use this with android lifestyle components, specifically in Observer I have to check for null.
How can I avoid this null check? This happens because of
void onChanged(@Nullable T t);
in Observer. I've tried to extend this but it seem to require more custom wrapper classes. Do we have a solution for avoid null check here.
android kotlin android-lifecycle asked Nov 22 '18 at 6:22
Ruwanka MadhushanRuwanka Madhushan
1,64632037
I have Result wrapper that wraps data comes from backend
data class Result<T>(val success: Boolean, val result: T?, val message: String?)
Idea of this, check success instead of result being null or not valid and get formatted message for UI error reporting. But when trying to use this with android lifestyle components, specifically in Observer I have to check for null.
How can I avoid this null check? This happens because of
void onChanged(@Nullable T t);
in Observer. I've tried to extend this but it seem to require more custom wrapper classes. Do we have a solution for avoid null check here.
android kotlin android-lifecycle android kotlin android-lifecycle asked Nov 22 '18 at 6:22
Ruwanka MadhushanRuwanka Madhushan
1,64632037
asked Nov 22 '18 at 6:22
Ruwanka MadhushanRuwanka Madhushan
1,64632037
asked Nov 22 '18 at 6:22
Ruwanka MadhushanRuwanka Madhushan
1,64632037
asked Nov 22 '18 at 6:22
Ruwanka MadhushanRuwanka Madhushan
1,64632037
asked Nov 22 '18 at 6:22
Ruwanka MadhushanRuwanka Madhushan
1,64632037
1,64632037
I think its mostly because the output(Result<Location>?) can be either success or Null. Therefore it is asking you to add a safe operator check to avoid that. So I think it should beit?.successor you can do aletoperator on the result.
– ASN
Nov 22 '18 at 6:35
1
Your right from one perspective, but since we handling the updates ofMutableLiveDatawe can make sure thatnullis not posted as result
– Ruwanka Madhushan
Nov 22 '18 at 6:38
add a comment |
I think its mostly because the output(Result<Location>?) can be either success or Null. Therefore it is asking you to add a safe operator check to avoid that. So I think it should beit?.successor you can do aletoperator on the result.
– ASN
Nov 22 '18 at 6:35
1
Your right from one perspective, but since we handling the updates ofMutableLiveDatawe can make sure thatnullis not posted as result
– Ruwanka Madhushan
Nov 22 '18 at 6:38
I think its mostly because the output(Result<Location>?) can be either success or Null. Therefore it is asking you to add a safe operator check to avoid that. So I think it should be
it?.success or you can do a let operator on the result.– ASN
Nov 22 '18 at 6:35
I think its mostly because the output(Result<Location>?) can be either success or Null. Therefore it is asking you to add a safe operator check to avoid that. So I think it should be
it?.success or you can do a let operator on the result.– ASN
Nov 22 '18 at 6:35
1
1
Your right from one perspective, but since we handling the updates of
MutableLiveData we can make sure that null is not posted as result– Ruwanka Madhushan
Nov 22 '18 at 6:38
Your right from one perspective, but since we handling the updates of
MutableLiveData we can make sure that null is not posted as result– Ruwanka Madhushan
Nov 22 '18 at 6:38
add a comment |
2 Answers
2
active
oldest
votes
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 '18 at 6:28
Andrei VinogradovAndrei Vinogradov
748417
add a comment |
Updated answer from @Andrei Vinogradov's answer
Until you upgrade to 2.0.0-beta01, you can try this solution. Use standard function let from Kotlin library :
it?.let{ result ->
if(result.success){
// Rest of your code ..
}
}
answered Nov 22 '18 at 6:34
Jeel VankhedeJeel Vankhede
2,3672419
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 '18 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 '18 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 '18 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 '18 at 6:40
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 '18 at 6:28
Andrei VinogradovAndrei Vinogradov
748417
add a comment |
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 '18 at 6:28
Andrei VinogradovAndrei Vinogradov
748417
add a comment |
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 '18 at 6:28
Andrei VinogradovAndrei Vinogradov
748417
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 '18 at 6:28
Andrei VinogradovAndrei Vinogradov
748417
answered Nov 22 '18 at 6:28
Andrei VinogradovAndrei Vinogradov
748417
answered Nov 22 '18 at 6:28
Andrei VinogradovAndrei Vinogradov
748417
answered Nov 22 '18 at 6:28
Andrei VinogradovAndrei Vinogradov
748417
748417
add a comment |
add a comment |
Updated answer from @Andrei Vinogradov's answer
Until you upgrade to 2.0.0-beta01, you can try this solution. Use standard function let from Kotlin library :
it?.let{ result ->
if(result.success){
// Rest of your code ..
}
}
answered Nov 22 '18 at 6:34
Jeel VankhedeJeel Vankhede
2,3672419
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 '18 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 '18 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 '18 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 '18 at 6:40
add a comment |
Updated answer from @Andrei Vinogradov's answer
Until you upgrade to 2.0.0-beta01, you can try this solution. Use standard function let from Kotlin library :
it?.let{ result ->
if(result.success){
// Rest of your code ..
}
}
answered Nov 22 '18 at 6:34
Jeel VankhedeJeel Vankhede
2,3672419
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 '18 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 '18 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 '18 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 '18 at 6:40
add a comment |
Updated answer from @Andrei Vinogradov's answer
Until you upgrade to 2.0.0-beta01, you can try this solution. Use standard function let from Kotlin library :
it?.let{ result ->
if(result.success){
// Rest of your code ..
}
}
answered Nov 22 '18 at 6:34
Jeel VankhedeJeel Vankhede
2,3672419
Updated answer from @Andrei Vinogradov's answer
Until you upgrade to 2.0.0-beta01, you can try this solution. Use standard function let from Kotlin library :
it?.let{ result ->
if(result.success){
// Rest of your code ..
}
}
answered Nov 22 '18 at 6:34
Jeel VankhedeJeel Vankhede
2,3672419
answered Nov 22 '18 at 6:34
Jeel VankhedeJeel Vankhede
2,3672419
answered Nov 22 '18 at 6:34
Jeel VankhedeJeel Vankhede
2,3672419
answered Nov 22 '18 at 6:34
Jeel VankhedeJeel Vankhede
2,3672419
2,3672419
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 '18 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 '18 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 '18 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 '18 at 6:40
add a comment |
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 '18 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 '18 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 '18 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 '18 at 6:40
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 '18 at 6:36
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 '18 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 '18 at 6:38
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 '18 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 '18 at 6:40
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 '18 at 6:40
1
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 '18 at 6:40
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 '18 at 6:40
add a comment |
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I think its mostly because the output(Result<Location>?) can be either success or Null. Therefore it is asking you to add a safe operator check to avoid that. So I think it should be
it?.successor you can do aletoperator on the result.– ASN
Nov 22 '18 at 6:35
1
Your right from one perspective, but since we handling the updates of
MutableLiveDatawe can make sure thatnullis not posted as result– Ruwanka Madhushan
Nov 22 '18 at 6:38