How to Fix "The Expression of Type List Needs Unchecked Conversion...'

How do I fix The expression of type List needs unchecked conversion...'?

Since getEntries returns a raw List, it could hold anything.

The warning-free approach is to create a new List<SyndEntry>, then cast each element of the sf.getEntries() result to SyndEntry before adding it to your new list. Collections.checkedList does not do this checking for you—although it would have been possible to implement it to do so.

By doing your own cast up front, you're "complying with the warranty terms" of Java generics: if a ClassCastException is raised, it will be associated with a cast in the source code, not an invisible cast inserted by the compiler.

How to avoid : The expression of type List needs unchecked conversion to conform to..

add this above the line or in top of the method header:

@SuppressWarnings("unchecked")
List<Book> bookList = session.createCriteria(Book.class)
            .add(Restrictions.like("name", "%i%")).list();

or for the whole method:

@SuppressWarnings("unchecked")
public void doSomething(){

in case list() would be your own implementation you could define the result like this:

private List<Book> list(){
    return new ArrayList<Book>();
  }

then the annotation is not necessary and you have a checked conversion controlled by the compiler.

How to eliminate The expression of type List needs unchecked conversion to conform warning?

in Intellij Idea getting "Redundant array creation for calling varargs method" warning, which fixed by removing 'new String []{ and }' so try

        new ArrayList<String>(Arrays.asList("constant",
                "append",
                "insertupdate",
                "tableinput",
                "filterrows",
                "dblookup",
                "selectvalues"))

to fix the issue

Type safety: The expression of type List needs unchecked conversion to conform to ListObject[]

Hibernate's Session.list() returns a plain, raw List.

It is perfectly legal Java syntax to cast it to a parameterized collection (List<Object[]> here). But due to the fact that generic type infos are wiped out at runtime, the compiler will emit a warning to tell you it cannot guarantee this cast will actually be valid.
So it's just his way to tell you "Hey, you're playing with fire here, I hope you know what you do, because I don't".

In this particular case, you can't do anything to eliminate this warning, but you can take the responsibility of explicitely ignoring it by using the @SuppressWarnings annotation.

Type safety: The expression of type ArrayList needs unchecked conversion to conform to ArrayListStudent? This throws a ClassCastException

It seems like you did not serialize a list of Students (which is an own object) but Students one by one. Therefore you should either serialize a list or you should deserialize the Students one by one (by continously calling readObject()).

Try this (using try-with-resources):

public void readStudentInfo() {
    try (FileInputStream fis = new FileInputStream("student.ser");
            ObjectInputStream ois = new ObjectInputStream(fis)) {
        List<Student> deserializedStudents = new ArrayList<>();
        while (fis.available() > 0) {
            deserializedStudents.add((Student) ois.readObject());
        }
        deserializedStudents.foreach(student -> System.out.println(student));
    } catch(IOException | ClassNotFoundException exc){
        exc.printStackTrace();
    }        
}

Type safety: The expression of type List needs unchecked conversion to conform to Collection? extends Object

Eclipse did the mess:

Wrong:

import edu.emory.mathcs.backport.java.util.Arrays;

Correct:

import jave.util.Arrays;

So code is ok both versions Set<?> and Set<String>. Eclipse just auto imported bad class.

Continuous Integration Servers

I recently implemented a Hudson server. Having previously used Cruise Control, I am very satisfied with Hudson and very impressed with its ease of setup and use. Adding new projects is infinitely easier than it was with Cruise Control.

The expression of type List needs unchecked conversion to conform to ListStudent, when using Hibernate Criteria

Moved from comment:
You want to cast a Criteria object? That makes no sense. criteria.list() returns a List, so you could just use that.

The castList method is odd anyways, you don't gain any compile-time type-safety (it will still only fail at runtime if something is wrong), and it could slow things down, especially if the list is long. I'd just use @SuppressWarnings or live with the warning.

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