How can I address the unchecked cast warnings

0 votes

Eclipse is giving me a warning of the following form:

Type safety: Unchecked cast from Object to HashMap

This is from a call to an API that I have no control over which returns Object:

HashMap<String, String> getItems(javax.servlet.http.HttpSession session) {
  HashMap<String, String> theHash = (HashMap<String, String>)session.getAttribute("attributeKey");
  return theHash;
}
I'd like to avoid Eclipse warnings, if possible, since theoretically they indicate at least a potential code problem. I haven't found a good way to eliminate this one yet, though. I can extract the single line involved out to a method by itself and add @SuppressWarnings("unchecked") to that method, thus limiting the impact of having a block of code where I ignore warnings. Any better options? I don't want to turn these warnings off in Eclipse.
Sep 25, 2018 in Java by Sushmita
• 6,910 points
24,393 views

2 answers to this question.

0 votes

The obvious answer, of course, is not to do the unchecked cast.

If it's absolutely necessary, then at least try to limit the scope of the @SuppressWarningsannotation. According to its Javadocs, it can go on local variables; this way, it doesn't even affect the entire method.

Example:

@SuppressWarnings("unchecked")
Map<String, String> myMap = (Map<String, String>) deserializeMap();

There is no way to determine whether the Map really should have the generic parameters <String, String>. You must know beforehand what the parameters should be (or you'll find out when you get a ClassCastException). This is why the code generates a warning, because the compiler can't possibly know whether is safe.

answered Sep 25, 2018 by Daisy
• 8,120 points
+1 vote
@SuppressWarnings("unchecked")
answered Mar 21, 2019 by anonymous
Yup. That works :)

Related Questions In Java

0 votes
2 answers

What is the use of toString method in Java and how can I use it ?

Whenever you require to explore the constructor ...READ MORE

answered Aug 23, 2018 in Java by Daisy
• 8,120 points
3,758 views
0 votes
2 answers

How can I invoke a method when the method name is in the form of a given string?

You could probably use method invocation from reflection: Class<?> ...READ MORE

answered Aug 19, 2019 in Java by Sirajul
• 59,230 points
2,517 views
0 votes
2 answers

How can I get the filenames of all files in a folder which may or may not contain duplicates

List<String> results = new ArrayList<String>(); File[] files = ...READ MORE

answered Sep 12, 2018 in Java by Sushmita
• 6,910 points
1,634 views
0 votes
6 answers

How can I separate the digits of an int number in Java?

You can also have a look here: To ...READ MORE

answered Dec 9, 2020 in Java by Roshni
• 10,520 points
203,225 views
0 votes
1 answer

How can I make the return type of a method generic?

First of all, define callFriend: public <T extends ...READ MORE

answered May 19, 2018 in Java by sharth
• 3,370 points
603 views
0 votes
2 answers

How can I split the String with any whitespace character as delimiter?

String string = "Today's weather"; String[] arrayOfString = ...READ MORE

answered Aug 23, 2019 in Java by Sirajul
• 59,230 points
771 views
+5 votes
4 answers

How to execute a python file with few arguments in java?

You can use Java Runtime.exec() to run python script, ...READ MORE

answered Mar 27, 2018 in Java by DragonLord999
• 8,450 points

edited Nov 7, 2018 by Omkar 79,311 views
+1 vote
1 answer

How to handle drop downs using Selenium WebDriver in Java

First, find an XPath which will return ...READ MORE

answered Mar 27, 2018 in Selenium by nsv999
• 5,500 points
7,922 views
0 votes
1 answer

What are the differences between getText() and getAttribute() functions in Selenium WebDriver?

See, both are used to retrieve something ...READ MORE

answered Apr 5, 2018 in Selenium by nsv999
• 5,500 points
16,941 views
0 votes
1 answer

Selenium JARS(Java) missing from downloadable link

Nothing to worry about here. In the ...READ MORE

answered Apr 5, 2018 in Selenium by nsv999
• 5,500 points

edited Aug 4, 2023 by Khan Sarfaraz 4,358 views
webinar REGISTER FOR FREE WEBINAR X
REGISTER NOW
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP