What is the easiest way to test (using reflection), whether given method (i.e. java.lang.Method instance) has a return type, which can be safely casted to List<String>?
Consider this snippet:
public static class StringList ...
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can please help in understand difference between unbounded wildcard type List and raw type List
List a;
List<?>;
along with this can anybody help me to understand BOUNDED TYPE PARAMETER LIST
List<E extends Number>;
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I have to define a List and it has two types of possible values
1)String
2)some user defined Class
How can I make a List that is type safe in that it only accepts ... |
I have a List that is guaranteed to contain just one type object. This is created by some underlying code in a library that I cannot update. I ... |
I have;
List<String> stringList = new ArrayList<String>();
List<Integer> integerList = new ArrayList<Integer>();
Is there a (easy) way to retrieve the generic type of the list?
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I have a heterogeneous List that can contain any arbitrary type of object. I have a need to find an element of the List that is of a certain type. Looking ... |
Take the following:
public Class<List<String>> getObjectType() {
// what can I return here?
}
What class literal expression can I return from this method which will satisfy the generics and compile? ... |
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I saw sometimes a type object inside <> beside of another object type declaration.
For instance:
NavigableMap<Double, Integer> colorMap = new TreeMap<Double, Integer>()
or
private final CopyOnWriteArrayList<EventListener> ListenerRecords =
new CopyOnWriteArrayList<EventListener>();
Could you give ... |
I want to make a growable array of bytes. I.e a list.
In c# would usally do the following syntax
List<byte> mylist = new List<byte>();
where as in java this syntax does not work ... |
I am trying to use a common technique to create objects from Xml. (Xml is legacy, so although there are already libraries to do this, it seemed faster to write this ... |
I have a List<?> listin Java.
Is there a way to determine the type of the contents of that list at runtime when the list is empty?
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I would like some variant of this code to compile in java.
class X
{
List<X> getvalue(){...};
}
class Y extends X
{
List<Y> getvalue(){...};
}
Javac (1.6) returns an error because ... |
I have a question about generics.
I have a function that knows about a class type of object that I want to create:
public static <T> XmlParserInterface<T> createXmlParser(Class<T> rootType, String currentTagName) {
XmlParserInterface<T> ...
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I have the below function:
public <T> void putList(String key, List<T> lst){
if (T instanceof String) {
...
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I want to store a collection of objects that are keyed based upon a value they represent. These keys can be repeated. e.g.:
[4] => Bob
[5] => Mary
...
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I understand why I cannot do the following:
private class Parent {
};
private class Child extends Parent {
};
private class GrandChild extends Child {
};
public void wontCompile(List<? extends Parent> genericList, Child itemToAdd) {
...
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Hey, I'm initializing a ListRepository with two different types of initialization lists. The best way would be something like this.
public ListRepository(String id, List<PrimaryKey> initilizationList)
{
// Load objects from data ...
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Consider the following piece of code:
class Test{
static <T> List<T> lstOf(T ...values){
List<T> lst = new ArrayList<T>(values.length);
for ( T ...
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Sorry for the cryptic title, but this is difficult to explain. The general rule is that I need a lazy loader that will give me N instances of a bound wildcard ... |
I'm trying to write a function in three classes that will compare two lists of objects of that same class.
General Idea
List<Toads> aTList = ...
List<Toads> bTList = ...
List<Toads> tResult = compare(aTList ...
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I've come into something I haven't come across before in Java and that is, I need to create a new instance of say the ArrayList class at runtime without assigning a ... |
I have a list of lists.
I would like to know how I can restrict the generic types of each of the inner lists so each element of the outer list ... |
Lists or Iterables can be filtered easily using guavas filter(Iterable<?> unfiltered, Class<T> type). This operation performs two tasks: the list is filtered and transformed into a sequence of the ... |
I have a class that has a propery List<String> or List<SomeObject>.
I get the type of the property as this:
propertyClass = PropertyUtils.getPropertyType(currentObject, property);
What I want to do is check that the ... |
There is a way to cheat around this. Both methods are the same because after the generics are removed, both are the same: void someMethod(List). If you give them different return types however, it will work: void someMethod(List l); int someMethod(List l); After the generics are removed (this process is called erasure), the two are different. Of course it seems strange ... |
Originally posted by Jothi Shankar Kumar Sankararaj: I really did not get your explanation. Can you be a bit clear? You have a List. You then cast it to an Object, which is just perfectly legal. After all, every non-primitive IS-A Object in Java. However, then you are casting it to List. The compiler gives you a warning. It doesn't give ... |
I have an interface, Human, and a bunch of subclasses: Users, Managers, Clowns, etc. My utility functions return List Some of the public functions want to return List of specific types, say a List What is the cleanest way to downcast the result so we can return List when the worker function returns a List which is ... |
I get this warning below when working with ArrayList...it's only a warning not an error.my code is below 1)java.util.List resim_no = new ArrayList(); 2)resim_no.add(SQL.sonuc.getString("Resim_No")); //this code is in a loop 3)String [] Aresim_no=(String[])resim_no.toArray(new String[resim_no.size()]); 2. and 3. codes makes that warning.And warning says; Type safety: The method toArray(Object[]) belongs to the raw type List. References to generic type List should be ... |