This question already has answers here:
Idiomatic way to create a Stream from a Nullable object
(7 answers)
Closed 4 years ago.
The following code gives me a NullPointerException. As my examine, it is caused by containerModels being null.
List<DoseDetailMutableDTOToBaseDoseDetailAdapter> adapters =
containerModels.stream()
.map(DoseDetailMutableDTOToBaseDoseDetailAdapter::new)
.collect(Collectors.toList());
How to fix it using java 8?
This could do the trick:
Optional.ofNullable(containerModels)
.orElse(Collections.emptyList())
.stream()
...
Related
This question already has answers here:
Filter values only if not null using lambda in Java8
(6 answers)
Filter null values after map in Java 8 [duplicate]
(1 answer)
Closed 6 months ago.
Let's say I have a Java Stream that contains null values.
How do you remove them ?
Here's a few ways I can think of:
stream.filter(x -> x != null).
stream.filter(Objects::nonNull)
This question already has answers here:
Please explain the usage of Labeled Statements
(3 answers)
Java Label usage [duplicate]
(2 answers)
"loop:" in Java code. What is this, and why does it compile?
(12 answers)
Should I avoid using Java Label Statements?
(12 answers)
Closed 4 years ago.
I've read some tutorials which using this syntax in Java, but I don't know what it's mean?
newNumber:while (1 <= 500) {
// do something
}
I don't understand what newNumber:while mean and I can't find it on oracle documentation.
newValue is label here. You can use it with break and continue statement. It becomes relevant for nesting loops when you want to jump from inside the nested loop.
This question already has answers here:
Return value from Optional [closed]
(1 answer)
Java Optional if object is not null - returns the method result, if null - returns default value
(6 answers)
Closed 4 years ago.
I often find myself using this idiom:
AtomicReference<MyCoolObject> coolReference = new AtomicReference(new MyCoolObject());
getOptionalValue().ifPresent(presentValue -> {
coolReference.set(new MyCoolObject(presentValue));
});
return coolReference.get();
Is this a bad habit, or a legitimate use of AtomicReference?
This question already has answers here:
C# getting its own class name
(11 answers)
Closed 7 years ago.
I am trying to rewrite Java code to C# and I am facing the problem that C# has not got this Java method. Can you please give me the C#'s equivalent of this method or some other way to get the class name.
you can do it like this:
typeof(ClassName).Name
This question already has answers here:
Java array, NullPointerException?
(2 answers)
Closed 7 years ago.
I am writing a simple java code but it gave me error of NullPointerException. My code is
String s="google";
ArrayList ss[]=new ArrayList[2];
ss[0].add(s);
System.out.println(ss[0]);
When you create the array, you do not create each element of the array. This will work:
ss[0] = new ArrayList();
ss[0].add(s);