Make Android Lifecycle Observer receiver non nullable in Kotlin
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0
down vote
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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 at 6:22
Ruwanka Madhushan
1,50022036
add a comment |
up vote
0
down vote
favorite
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 at 6:22
Ruwanka Madhushan
1,50022036
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 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 at 6:38
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
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 at 6:22
Ruwanka Madhushan
1,50022036
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 at 6:22
Ruwanka Madhushan
1,50022036
asked Nov 22 at 6:22
Ruwanka Madhushan
1,50022036
asked Nov 22 at 6:22
Ruwanka Madhushan
1,50022036
asked Nov 22 at 6:22
Ruwanka Madhushan
1,50022036
asked Nov 22 at 6:22
Ruwanka Madhushan
1,50022036
1,50022036
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 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 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 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 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 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 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 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 at 6:38
add a comment |
2 Answers
2
active
oldest
votes
up vote
3
down vote
accepted
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 at 6:28
Andrei Vinogradov
584316
add a comment |
up vote
2
down vote
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 at 6:34
Jeel Vankhede
2,0461216
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 at 6:40
add a comment |
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
accepted
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 at 6:28
Andrei Vinogradov
584316
add a comment |
up vote
3
down vote
accepted
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 at 6:28
Andrei Vinogradov
584316
add a comment |
up vote
3
down vote
accepted
up vote
3
down vote
accepted
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 at 6:28
Andrei Vinogradov
584316
It's a framework bug that argument is annotated as @Nullable. Fixed in androix.lifecycle 2.0.0-beta01.
answered Nov 22 at 6:28
Andrei Vinogradov
584316
answered Nov 22 at 6:28
Andrei Vinogradov
584316
answered Nov 22 at 6:28
Andrei Vinogradov
584316
answered Nov 22 at 6:28
Andrei Vinogradov
584316
584316
add a comment |
add a comment |
up vote
2
down vote
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 at 6:34
Jeel Vankhede
2,0461216
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 at 6:40
add a comment |
up vote
2
down vote
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 at 6:34
Jeel Vankhede
2,0461216
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 at 6:40
add a comment |
up vote
2
down vote
up vote
2
down vote
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 at 6:34
Jeel Vankhede
2,0461216
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 at 6:34
Jeel Vankhede
2,0461216
answered Nov 22 at 6:34
Jeel Vankhede
2,0461216
answered Nov 22 at 6:34
Jeel Vankhede
2,0461216
answered Nov 22 at 6:34
Jeel Vankhede
2,0461216
2,0461216
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 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 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 at 6:40
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 at 6:40
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 at 6:36
I'd like to have no code at all to check nulls. But this works otherwise, thanks
– Ruwanka Madhushan
Nov 22 at 6:36
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 at 6:38
Yah, there's no other workaround for now :).
– Jeel Vankhede
Nov 22 at 6:38
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 at 6:40
Kotlin extension would work, right?
– Ruwanka Madhushan
Nov 22 at 6:40
1
1
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 at 6:40
Yes, it works. I'm using that too.
– Jeel Vankhede
Nov 22 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 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 at 6:38