I’m using Eclipse to generate .equals() and .hashCode(), and there is an option labeled “Use ‘instanceof’ to compare types”. The default is for this option to be unchecked and use .getClass() to compare types. Is there any reason I should prefer .getClass() over instanceof? Without using instanceof: if (obj == null) return false; if (getClass() … Read more
What is the preferred method to achieve the C++ equivalent of java’s instanceof? 5 Answers 5
This is a really basic question really just to satisfy my curiosity, but is there a way to do something like this: if(obj !instanceof Array) { //The object is not an instance of Array } else { //The object is an instance of Array } The key here being able to use the NOT ! … Read more
This question already has answers here: Closed 10 years ago. What is the ‘instanceof’ operator used for? I learned that Java has the instanceof operator. Can you elaborate where it is used and what are its advantages? 4 Answers 4
“foo” instanceof String //=> false “foo” instanceof Object //=> false true instanceof Boolean //=> false true instanceof Object //=> false false instanceof Boolean //=> false false instanceof Object //=> false 12.21 instanceof Number //=> false /foo/ instanceof RegExp //=> true // the tests against Object really don’t make sense Array literals and Object literals match… … Read more
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 instanceof C) doC(): How would it be implemented using switch…case? 24 Answers 24
I am working on an application and one design approach involves extremely heavy use of the instanceof operator. While I know that OO design generally tries to avoid using instanceof, that is a different story and this question is purely related to performance. I was wondering if there is any performance impact? Is is just … Read more
The instanceof keyword in JavaScript can be quite confusing when it is first encountered, as people tend to think that JavaScript is not an object-oriented programming language. What is it? What problems does it solve? When is it appropriate and when not? 11 Answers 11
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 25 Answers 25 Use instanceof for custom types: var ClassFirst = function () {}; var ClassSecond = function () {}; var instance = new ClassFirst(); typeof instance; // object typeof … Read more
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 throws an exception. Other than that, do they always give the same result? 14 s 14 When using instanceof, you need to know the class … Read more
