instanceof Questions
3
Solved
I would like to know regarding following behavior of instanceof operator in Java.
interface C {}
class B {}
public class A {
public static void main(String args[]) {
B obj = new B();
System.o...
Skepful asked 14/7, 2015 at 5:39
3
Solved
I have Java 19, and I am attempting to do some simple pattern-matching on a record that I created. However, Java is giving me a very confusing compilation error. Here is the simplest example I coul...
Subtenant asked 2/1, 2023 at 2:46
5
Solved
I am going through Oracle's official docs to understand Pattern Variable scope in Java 17. In the following example, the method testScope1 works as explained in the docs, but the method testScope2 ...
Glairy asked 16/9, 2022 at 12:24
6
Solved
I have the following expression:
scheduleIntervalContainers.stream()
.filter(sic -> ((ScheduleIntervalContainer) sic).getStartTime() != ((ScheduleIntervalContainer)sic).getEndTime())
.collect...
Hearsh asked 2/3, 2016 at 7:3
11
Solved
Dart specification states:
Reified type information reflects the types of objects at runtime and may always be queried by dynamic typechecking constructs (the
analogs of instanceOf, casts, type...
Sense asked 10/10, 2011 at 16:39
16
Solved
Which of the following is better?
a instanceof B
or
B.class.isAssignableFrom(a.getClass())
The only difference that I know of is, when 'a' is null, the first returns false, while the second t...
Madelle asked 30/1, 2009 at 19:44
27
Solved
In my particular case:
callback instanceof Function
or
typeof callback == "function"
does it even matter, what's the difference?
Additional Resource:
JavaScript-Garden typeof vs instanceof...
Subsistence asked 22/5, 2009 at 19:24
5
Solved
How can I find the variable type in Kotlin?
In Java there is instanceof, but in Kotlin it does not exist:
val properties = System.getProperties() // Which type?
Melon asked 18/7, 2017 at 11:12
4
Solved
How to test if a val/var is of an expected type?
Is there something I am missing in Kotlin Test, like:
value shouldBe instanceOf<ExpectedType>()
Here is how I implemented it:
inline fun...
Keratose asked 29/4, 2019 at 11:52
11
Solved
"foo" instanceof String //=> false
"foo" instanceof Object //=> false
true instanceof Boolean //=> false
true instanceof Object //=> false
false instanceof Boolean ...
Vaccaro asked 15/10, 2008 at 4:44
5
It has been repeatedly said that the instanceof operator should not be used except in the equals() method, otherwise it's a bad OOP design.
Some wrote that this is a heavy operation, but it seems t...
Dougald asked 14/12, 2013 at 23:46
29
Solved
I have a question of using switch case for instanceof object:
For example: my problem can be reproduced in Java:
if(this instanceof A)
doA();
else if(this instanceof B)
doB();
else if(this inst...
Shawannashawl asked 7/4, 2011 at 10:3
15
Solved
Is there any way to efficiently check if the variable is Object or Array, in NodeJS & V8?
I'm writing a Model for MongoDB and NodeJS, and to traverse the object tree I need to know if the obj...
Papyrus asked 12/1, 2012 at 11:12
1
Solved
I am building a library with TS. This library uses the ssh2 library as a dependency.
I'm trying to create a function that can either accept an ssh2 configuration object or an already existing Clien...
Cause asked 10/4, 2023 at 11:19
3
Solved
It is possible to replace block of if( .. instanceof ...), elseif(... instanceof ...), ... with switch?
For example:
<?php
$class = ..... //some class
if($class instanceof SomeClass) {
//do ...
Louettalough asked 4/5, 2016 at 13:27
12
Solved
How do I find out the name of the class used to create an instance of an object in Python?
I'm not sure if I should use the inspect module or parse the __class__ attribute.
Gualterio asked 4/2, 2009 at 11:37
3
Solved
Background
With a bit of research I've found that, although ArrayBufferView wasn't initially exposed (through [NoInterfaceObject]) there appeared to be broad agreement that it should be, due to my...
Petersburg asked 13/2, 2014 at 11:57
5
I'm having issues using the instanceof operator and it doesn't seem to work. Here is a part of my code:
const results = _.map(items, function(item: Goal|Note|Task, index: number) {
let result =...
Quadric asked 30/8, 2017 at 15:10
6
Solved
I wrote this code
interface Foo {
abcdef: number;
}
let x: Foo | string;
if (x instanceof Foo) {
// ...
}
But TypeScript gave me this error:
'Foo' only refers to a type, but is being used a...
Vial asked 12/10, 2017 at 7:1
2
Solved
Can someone explain me why the error instanceof CustomError part of below code is false ?
class CustomError extends Error {}
const error = new CustomError();
console.log(error instanceof Error)...
Diffidence asked 11/5, 2017 at 9:55
4
Solved
In the spirit of the c# question..
What is the equivalent statements to compare class types in VB.NET?
Dodge asked 16/6, 2009 at 23:56
3
In PHP there is two classes:
class parentTroll {...} and class troll extends parentTroll {...}
And then there is an object $troll = new troll();
How to check $troll instanceof parentTroll? This l...
Evangelical asked 21/5, 2014 at 10:57
5
I'm debugging a C++ program with GDB.
I have a pointer to an object of certain class. The pointer is declared to be of some super class which is extended by several sub-classes.
There is no field...
Recreate asked 16/12, 2011 at 1:59
10
Solved
Having a chain of "instanceof" operations is considered a "code smell". The standard answer is "use polymorphism". How would I do it in this case?
There are a number of subclasses of a base class;...
Selfdiscipline asked 7/5, 2010 at 16:37
2
My code runs in intellij on java 17 but returns an error on java 14 for the following line:
if (this.areas.get(i) instanceof Habitat area) {
which returns the error:
java: pattern matching in...
Ping asked 5/4, 2022 at 20:50
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