How to wait for RxJava asynchronous call to complete before continuing to the rest of the code?
I'm using Architecture Components. This app shows a bunch of products to users. In the repository I have a function fetchProducts() that should fetch products that are not yet in the database. To do this I first need to query the database to find the most recent product(they have a date) there so that I don't fetch products that already in the database. Now this is obviously very important as I don't want to do more work than needed. How do I wait for the asynchronous call to finish? This is what I tried:
LiveData<Boolean> fetchProducts() {
MutableLiveData<Boolean> booleanLoadingComplete = new MutableLiveData<>();
final CountDownLatch countDownLatch = new CountDownLatch(1);
final ProductWrapper productWrapper = new ProductWrapper();
productDao.getMostRecentProduct()
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<ProductEntity>() {
@Override
public void accept(ProductEntity productEntity) throws Exception {
productWrapper.product = productEntity;
countDownLatch.countDown();
}
});
try {
countDownLatch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
// now we should be able to safely proceed with the rest of the code
// more code goes here...
return booleanLoadingComplete;
}
Using CountDownLatch seemed like a good idea but when I tried this the app simply froze showing a blank screen.
This is the Dao. I'm beginner with RxJava and I don't know if Flowable is appropriate for this case.
@Dao
public interface ProductDao {
@Insert(onConflict = OnConflictStrategy.REPLACE)
void insert(ProductEntity product);
@Query("SELECT * FROM product ORDER BY published_at DESC")
LiveData<List<ProductEntity>> getProducts();
@Query("SELECT * FROM product ORDER BY published_at DESC LIMIT 1")
Flowable<ProductEntity> getMostRecentProduct();
}
android multithreading rx-java2 
android-architecture-components ui-thread asked Nov 22 '18 at 14:59
xplandxpland
32
add a comment |
I'm using Architecture Components. This app shows a bunch of products to users. In the repository I have a function fetchProducts() that should fetch products that are not yet in the database. To do this I first need to query the database to find the most recent product(they have a date) there so that I don't fetch products that already in the database. Now this is obviously very important as I don't want to do more work than needed. How do I wait for the asynchronous call to finish? This is what I tried:
LiveData<Boolean> fetchProducts() {
MutableLiveData<Boolean> booleanLoadingComplete = new MutableLiveData<>();
final CountDownLatch countDownLatch = new CountDownLatch(1);
final ProductWrapper productWrapper = new ProductWrapper();
productDao.getMostRecentProduct()
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<ProductEntity>() {
@Override
public void accept(ProductEntity productEntity) throws Exception {
productWrapper.product = productEntity;
countDownLatch.countDown();
}
});
try {
countDownLatch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
// now we should be able to safely proceed with the rest of the code
// more code goes here...
return booleanLoadingComplete;
}
Using CountDownLatch seemed like a good idea but when I tried this the app simply froze showing a blank screen.
This is the Dao. I'm beginner with RxJava and I don't know if Flowable is appropriate for this case.
@Dao
public interface ProductDao {
@Insert(onConflict = OnConflictStrategy.REPLACE)
void insert(ProductEntity product);
@Query("SELECT * FROM product ORDER BY published_at DESC")
LiveData<List<ProductEntity>> getProducts();
@Query("SELECT * FROM product ORDER BY published_at DESC LIMIT 1")
Flowable<ProductEntity> getMostRecentProduct();
}
asked Nov 22 '18 at 14:59
xplandxpland
32
2
you combine the logic into a single rx chain. At glance, I would suggest you to look into the flatMap operator. E.g.productDao.getMostRecentProduct().flatmap(product -> {someClass.fetchProducts(product.date)}).blabla.subscribe()
– Tim Castelijns
Nov 22 '18 at 15:08
add a comment |
I'm using Architecture Components. This app shows a bunch of products to users. In the repository I have a function fetchProducts() that should fetch products that are not yet in the database. To do this I first need to query the database to find the most recent product(they have a date) there so that I don't fetch products that already in the database. Now this is obviously very important as I don't want to do more work than needed. How do I wait for the asynchronous call to finish? This is what I tried:
LiveData<Boolean> fetchProducts() {
MutableLiveData<Boolean> booleanLoadingComplete = new MutableLiveData<>();
final CountDownLatch countDownLatch = new CountDownLatch(1);
final ProductWrapper productWrapper = new ProductWrapper();
productDao.getMostRecentProduct()
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<ProductEntity>() {
@Override
public void accept(ProductEntity productEntity) throws Exception {
productWrapper.product = productEntity;
countDownLatch.countDown();
}
});
try {
countDownLatch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
// now we should be able to safely proceed with the rest of the code
// more code goes here...
return booleanLoadingComplete;
}
Using CountDownLatch seemed like a good idea but when I tried this the app simply froze showing a blank screen.
This is the Dao. I'm beginner with RxJava and I don't know if Flowable is appropriate for this case.
@Dao
public interface ProductDao {
@Insert(onConflict = OnConflictStrategy.REPLACE)
void insert(ProductEntity product);
@Query("SELECT * FROM product ORDER BY published_at DESC")
LiveData<List<ProductEntity>> getProducts();
@Query("SELECT * FROM product ORDER BY published_at DESC LIMIT 1")
Flowable<ProductEntity> getMostRecentProduct();
}
asked Nov 22 '18 at 14:59
xplandxpland
32
I'm using Architecture Components. This app shows a bunch of products to users. In the repository I have a function fetchProducts() that should fetch products that are not yet in the database. To do this I first need to query the database to find the most recent product(they have a date) there so that I don't fetch products that already in the database. Now this is obviously very important as I don't want to do more work than needed. How do I wait for the asynchronous call to finish? This is what I tried:
LiveData<Boolean> fetchProducts() {
MutableLiveData<Boolean> booleanLoadingComplete = new MutableLiveData<>();
final CountDownLatch countDownLatch = new CountDownLatch(1);
final ProductWrapper productWrapper = new ProductWrapper();
productDao.getMostRecentProduct()
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<ProductEntity>() {
@Override
public void accept(ProductEntity productEntity) throws Exception {
productWrapper.product = productEntity;
countDownLatch.countDown();
}
});
try {
countDownLatch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
// now we should be able to safely proceed with the rest of the code
// more code goes here...
return booleanLoadingComplete;
}
Using CountDownLatch seemed like a good idea but when I tried this the app simply froze showing a blank screen.
This is the Dao. I'm beginner with RxJava and I don't know if Flowable is appropriate for this case.
@Dao
public interface ProductDao {
@Insert(onConflict = OnConflictStrategy.REPLACE)
void insert(ProductEntity product);
@Query("SELECT * FROM product ORDER BY published_at DESC")
LiveData<List<ProductEntity>> getProducts();
@Query("SELECT * FROM product ORDER BY published_at DESC LIMIT 1")
Flowable<ProductEntity> getMostRecentProduct();
}
asked Nov 22 '18 at 14:59
xplandxpland
32
asked Nov 22 '18 at 14:59
xplandxpland
32
asked Nov 22 '18 at 14:59
xplandxpland
32
asked Nov 22 '18 at 14:59
xplandxpland
32
asked Nov 22 '18 at 14:59
xplandxpland
32
32
2
you combine the logic into a single rx chain. At glance, I would suggest you to look into the flatMap operator. E.g.productDao.getMostRecentProduct().flatmap(product -> {someClass.fetchProducts(product.date)}).blabla.subscribe()
– Tim Castelijns
Nov 22 '18 at 15:08
add a comment |
2
you combine the logic into a single rx chain. At glance, I would suggest you to look into the flatMap operator. E.g.productDao.getMostRecentProduct().flatmap(product -> {someClass.fetchProducts(product.date)}).blabla.subscribe()
– Tim Castelijns
Nov 22 '18 at 15:08
2
2
you combine the logic into a single rx chain. At glance, I would suggest you to look into the flatMap operator. E.g.
productDao.getMostRecentProduct().flatmap(product -> {someClass.fetchProducts(product.date)}).blabla.subscribe()– Tim Castelijns
Nov 22 '18 at 15:08
you combine the logic into a single rx chain. At glance, I would suggest you to look into the flatMap operator. E.g.
productDao.getMostRecentProduct().flatmap(product -> {someClass.fetchProducts(product.date)}).blabla.subscribe()– Tim Castelijns
Nov 22 '18 at 15:08
add a comment |
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you combine the logic into a single rx chain. At glance, I would suggest you to look into the flatMap operator. E.g.
productDao.getMostRecentProduct().flatmap(product -> {someClass.fetchProducts(product.date)}).blabla.subscribe()– Tim Castelijns
Nov 22 '18 at 15:08