spot7.org logo
Home PHP C# C++ Android Java Javascript Python IOS SQL HTML Categories

Why did guava/java use possible.isPresent() as opposed to Optional.isPresent(possible)?


The idea of Optional is not to prevent all NPEs. The idea is to make it clear that an API method can return an absent value, and to force the caller to be aware of that and deal with it.

Of course, if this method returns null instead of an Optional, you'll still get a NPE, but that's a giant design issue. A method returning an Optional should return an Optional (present or absent), not null.

And it's much more natural, in a OO language, to access the state of an object using methods of this object rather than a static method.


Categories : Java

Related to : Why did guava/java use possible.isPresent() as opposed to Optional.isPresent(possible)?
is there a way in excel (as opposed to vba) to use index match to return a value with a max function in the matching criteria?
Try =INDEX(C2:C10,MATCH(MAX(IF(A2:A10=E1,B2:B10,0)),B2:B10,0)) This is an array formula and must be confirmed with CTRL-SHIFT-Enter

Categories : Excel
Big-O of containsValue for Guava HashBiMap
A PROPERLY IMPLEMENTED two-way HashMap (In this case, a HashBiMap) indeed has a runtime complexity of O(1) for containsKey and containsValue.

Categories : Java
Automatic cache refresh with Guava
A LoadingCache built with LoadingCache<K, V> cache = CacheBuilder.newBuilder() .refreshAfterWrite(15, TimeUnit.MINUTES) .maximumSize(100) .build(new MyCacheLoader()); will not refresh automatically by itself an entry every 15 minutes, as the cache does not create threads to do any kind of management (expiring or refreshing entries). If you call cache.get(someKey) t

Categories : Java
Guava cache for custom POJO
Use generics: class UserCacheLoader extends CacheLoader<Long, User> { @Override public User load(Long key) throws Exception { // ??? } } store(User) can be implemented with Cache.put, just like you'd expect. getKeys() can be implemented with cache.asMap().keySet().

Categories : Java
Compatable Guava version for JAVA 7
I don't think upgrading your Guava version will improve the performance. https://code.google.com/p/guava-libraries/wiki/ReleaseHistory Note: Releases 1 through 11 required JDK 1.5. Releases 12 and on require JDK 1.6. But you can always try the latest release 18.

Categories : Java
Recently Add
Redirecting the output directory of 'mvn package' or 'mvn compile' command
No suitable constructor found for ProductoExtranjero
java Composite design pattern(Directory &File)
Java JTree's ui refresh after removing node from parent
First REST Spring application
How to cancel Indexing of a Solr document using Update Request Processor
PowerMock - Mock a Singleton with a Private Constructor
Calling a Postgres stored function SQL error
Where to store Morphlines Java custom command class?
Generic repository using map
How can I scroll a ScrolledComposited in Eclipse SWT Design view?
2 Frames/layout in 1 Activity
Writing a switch differently
Next button opens another activity when its reaches the array limit
Is EclipseLink MOXy capable of applying JSR-303 Bean Validation when unmarshalling XML to object?
Why my jdk can't work,and before the java_home, there is a space that is not from me
How to add List of objects in a Map
How to make notepad++ function like regular notepad in cmd?
Cell renderer and the lost focus
how can I implement iterable for LinkedList>
Disable Androids image-crunch in eclipse (run as) builds
java 8 lambda myMap.stream().count() != myMap.size() after merging myMap
Issue with Calendar calculation that spans 2 calendar years
JSF 2.0 Spring bean injection
Java Regex ReplaceAll with grouping
Getting any word and last word using sed
Clicking on link on JEditorPane throws IOException
printing out difference of two arrays
Spring Bean Alias in JavaConfig
Using Factory Method to Create Generics
© Copyright 2017 spot7.org Publishing Limited. All rights reserved.