In Java 1.4.2, class java.math.BigInteger implements interfaces Comparable, Serializable.
In Java 1.5.0, class java.math.BigInteger implements interfaces Serializable, Comparable<BigInteger>.
This is just an example to help me ask about < ... |
With the type Integer you can do this:
int lowest = Integer.MIN_VALUE;
What can I do if I use generics?
K lowest = <...>;
I need this in order to implement something similar to a ... |
I'm really trying to like generics, but so far the trouble they've caused outweighs any benefits. Please, please show me I'm wrong.
I understand the necessity of adding @SuppressWarnings("unchecked") when using ... |
Anybody knows how to write the piece of code below using generics AND avoiding compiler warnings ? (@SuppressWarnings("unchecked") is considered cheating).
And, maybe, checking via generics that the type of "left" is ... |
Basically, I want an exact copy of the XML, except I'd like to sort certain nodes by their ID attribute. Not all elements with the ID attribute should be sorted. ... |
I need help in passing a Java Generics List to Collections.sort(). Here is my code:
List<MyObject> orgMyObjectList = new ArrayList<MyObject>();
Collections.sort(orgMyObjectList, new Comparable<MyObject>() {
public int ...
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Which is the quickest way in Java to sort a list
List<MyObject> myObjectList
based on some numerical property of MyObject?
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The title basically says it all: if I have a java method that is generic in T, can I find out anything about T? In particular, can I check whether ... |
The following gives me an error message:
public static List<Comparable<?>> merge(Set<List<Comparable<?>>> lists) {
List<Comparable<?>> result = new LinkedList<Comparable<?>>();
HashBiMap<List<Comparable<?>>, Integer> location = HashBiMap.create();
int totalSize;
for (List<Comparable<?>> l : lists) {
...
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I made an interface to work with JGraphT. My intended use is like Comparable, in that implementing Comparable allows objects to be used with certain data structures. Simiarly, I have a ... |
I have this Player class which implements the Comparable interface. Then I have an ArrayList of Players. I'm trying to use binarySearch() on the list of Players to find one Player, ... |
Suppose you write a static function in Java to sort an array, much like Arrays.sort(). The problem with Arrays.sort() is that it receives an array of Object, and throws a ClassCastException ... |
I want to have an interface A parameterised by T A<T>, and also want every class that implements it to also implement Comparable (with T and its subtypes). It would seem ... |
public abstract class MyAbs implements Comparable<MyAbs>
This would work but then I would be able to compare class A and B with each other if they both extend MyAbs. What I ... |
I'm upgrading some code to Java 5 and am clearly not understanding something with Generics. I have other classes which implement Comparable once, which I've been able to implement. But now ... |
I would like a method that takes a List<T> where T implements Comparable and returns true or false depending on whether the list is sorted or not.
What is the best way ... |
I have a litte problem and was wondering how to solve it. I have a generic class Tuple<A,B> and now I would like to sort their tuples according to A and ... |
I'm currently playing with implementing various sorting algorithms in Java, mostly for fun, but I'm struggling with how to do it 'right'. That is, I want the user to be able ... |
In Java, how would I use generics to create a max function that takes as parameters two Comparable objects of the same type and returns the larger one?
I tried:
public static <T ...
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This is an implementation of a container that can be compared to any other container with a compatible key. I have a weird error using generics in Java, any ideas?
...
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I am trying to implement generics in Java using Comparable<T> interface.
public static <T> T[] sort(T[] a) {
//need to compare 2 elements of a
}
Let's say, I want to ... |
I'm taking a data structures course, and we're using Data Structures and Algorithm Analysis in Java 2nd Edition by Mark Weiss. In his BinaryHeap implementation, his constructor creates a Comparable[] array ... |
If I call a (generic) varargs method with objects of different classes, I get an interesting warning:
List<?> result = Arrays.asList("1", 1);
A generic array of Object&Serializable&Comparable is created for ... |
public class GenericSort<G extends Comparable> {
private G[] integerarray;
public GenericSort(G[] inputarray){
this.integerarray = inputarray;
...
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I'm trying to implement a sorted list as a simple excercise in Java. To make it generic I have an "add(Comparable obj)" so I can use it with any class that ... |
I have a Generic Class with two type variables, which implements java.lang.Comparable.
public class DoubleKey<K,J> implements Comparable<DoubleKey<K,J>>{
private K key1;
private J key2;
... |
I wonder whether it is possible to cast a non-Comparable to something so that it matches the method parameter T which has template type <T extends Comparable<? super T>>, like the ... |
I want to create a kind of in-memory database into which I can put objects of any type that extends EntityProxy. I want to index every object according to its ... |
Going back over my basic ADT stuff here to revise for an interview, and trying to kill two birds with one stone by learning Java while I am. Attempting to write ... |
I have class, that contains different types and implements Iterable<Object> interface. But it is very important to me, that I can compare elements. I am aware, that I can not write ... |
What am I doing:
I have a container class named Os, that can contains different type elements and also instances of class Os. When I compare this class, I want to see ... |
When this class is created..
public static class TreeNode<E extends Comparable<E>>
what does the <E extends Comparable<E>> mean?
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I want to compare an array of comparables. The simplest way seems the following (details not shown):
public class ArrayComparable implements Comparable<ArrayComparable>{
ArrayList<Comparable<?>> list = new ArrayList<Comparable<?>>();
@Override
public int compareTo(ArrayComparable ac) {
...
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For whatever reason, despite the fact that it's entirely generic and works with integers whenever it's tested with strings it seems to skip the last iteration of merging. I've scoured my ... |
So I want to do this:
public interface IFieldObject {
public Comparable get();
}
public interface IFieldCondition {
public boolean apply(IFieldObject field, Comparable compare);
}
public class EqualTo implements IFieldCondition ...
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I am having some difficulty in being able to come up with an answer to the following question. I was able to know that it uses Generics and known that it ... |
I'm trying to write a generic max function that takes two Comparables.
So far I have
public static <T extends Comparable<?>> T max(T a, T b) {
if (a ...
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Here we have generic method:
public static <T extends Comparable<T>> T[] function(T[] a)
{
Object[] m = new Object[2];
/* some work here */
...
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I have a three class: 1.class Algorithm having max() finding maximum value in a Collection:
public class Algorithm {
public static <T extends Comparable<T>> T max(Collection<? extends T> coll) ...
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1 class test {
2 public static int compare0(Comparable x, Comparable y) {
3 return ...
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In the expression <T extends Comparable<T>> in a signature like
public static <T extends Comparable<T>> foo(T x) { ... }
the description of T depends recursively on Comparable<T>.
If T extends Comparable<T>, and Comparable<T> ... |
I have this method which unique parameter (List elements) sets elements to a ListModel, but I need to make a validation to see if the generic type implements comparable and since ... |
Consider this code:
public interface Foo extends Comparable<Foo> { ... }
public enum FooImpl implements Foo { ... }
Due to the restrictions of type erasure, I receive the following error:
java.lang.Comparable cannot be inherited ...
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I am creating a generic class that has a method that is supposed to sort through an array collection that may either be a Book or it may be a CD. ... |
This is my remove method for d-ary heaps. I'm getting a lot of 'inconvertible type' error when i compile. Also note that my program extends Comparable.
public class HeapImpl12<T extends Comparable<? super ...
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I am trying to figure out how to compare two items within a T[] array, here is what I have:
public static <T extends Comparable< ? super T>> T getLargest(T [] a, ...
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I have the following class.
class MyClass<T>
It uses the following constructor.
MyClass(Comparator<T> comparator, Collection<? extends T> data)
And it has a field which is set in the constructor like so:
this.data = Collections.unmodifiableCollection(data);
In the special ... |
I defined a generic class A<T> in Java, but I want to limit the type T such that it is a class which implements the Comparable<T> interface. What should i do?
... |
49. static > stackoverflow.comI have following class with one static method:
public class Helper {
public static <T extends Number & Comparable<? super Number>> Boolean inRange(T value, T minRange, T maxRange) {
...
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Suppose I have the following class (for demonstration purposes)
package flourish.lang.data;
public class Toyset implements Comparable<Toyset> {
private Comparable<?>[] trains;
@Override
public int compareTo(Toyset ...
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I have a generic java class that stores comparables:
public class MyGenericStorage<T extends Comparable<T>> {
private T value;
public MyGenericStorage(T value) {
...
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In Tiger, String implements Comparable . This means that instead of compareTo(Object), String has a compareTo(String) method. I've observed that older code along the lines of Object o = ... String s = ... int result = s.compareTo(o); won't actually compile under Tiger, and indeed, if you disassemble Tiger's java/lang/String.class, you find that the class file really doesn't contain the compareTo(Object) ... |
Hi, Gytis! Good question. After reading your question, I downloaded JDK 1.5.0 to try out your example and generics for the first time. By peeking a bit at chapter 9 of Gilid Bracha's excellent Generics tutorial, I found this to be the "correct" way to get rid of the unchecked warning: public enum Operation { MORE { public |
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Hello, colleagues. I am a tenderfoot here on the ranch and have a couple of problems that have been vexing me. One is a generics-arrays-sorting problem. In the following class, I generate an ArrayList of arrays of integer indices for chopping up a search string. To run it, compile the following code and enter a string to search and a list ... |
I'm trying to write a static sort class (for practice, I know that there is one already) that takes any ArrayList of comparable objects and sorts it. I've written a generic binary search tree before, but can't seem to get this started. class MySort { public static void sort (ArrayList> list) { qsort(list, 0, list.size() - 1); } ... |
You sparked my interest in what the differences would really be, so I wrote a test app to play around with the concept. Anywhere the file doesn't compile, we can see the limitations of each type of passing in a comparator import java.util.Comparator; public class FunComparator { public static class LessThanWidgetComparator implements Comparator { public int compare(LessThanWidget o1, LessThanWidget o2) { ... |
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Preface: I have the book Big Java by Horstmann. I also am using HF Java ed2. This is part of a project for school..... The Big Java text has a section about "sorting real data." It said to sort data I can implement the Comparable interface. Their example is as follows: public class Coin implements Comparable { public int compareTo(Object otherObject) ... |
I'm not quite "getting" generic usage yet. I have a custom container class and I'd like to pull out the smallest element from the list. Seems pretty straightforward, but I've been working on it for hours now. Here's my best try so far: public class MyArrayList extends MyListADT { // lots of stuff public static > ... |
Sort method in the Collections class looks like this: public static > void sort(List list) I understood the significance of which means the list which implements the comparable interface could be passed as an argument to the sort method. Consider the below example class Animal{} class Dog extends Animal implements Comparable{} Now i could ... |
Hello there i'm very new to learning about Generics. There is an exercise in Java How to Program by Paul and Harvey Deitel where i'm supposed to rewrite a method used in an earlier example but as a generic method. I've done it and it works fine but i keep getting this warning... Note: GenericSelectionSort.java uses unchecked or unsafe operations. Note: ... |
Hi For Input: [abc, abb, aaa, bbc] Collections.sort give: [aaa, abb, abc, bbc] I tried to implement something similar to it like this public static void doBubbleShort(List dataList) { for (int i = 0; i < dataList.size(); i++) { boolean oneSwap = false; for (int j = i; j < (dataList.size() - 1); j++) { if (((Comparable) (T) dataList.get(j)).compareTo((T) dataList.get(j ... |
Hello everyone. It's been a while since I've been to the forums, but I have a problem I just can't figure out. I'm trying to implement a node for a tree-based data structure (just a binary search tree to start with), and I want this node to have a key that is comparable. I would also like the node to be ... |
That's a warning, not an error, and you don't need to change your code for your code to work. To get rid of the warning, you can likely use an annotation (but I'm not sure which one). Otherwise, if you want to use generic typing to give your code compile-time type checking, then check out the tutorials on this at the ... |
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I'm trying to do a merge sort on double link list, but the list is generic. I'm having trouble finding a way that works for this. compareTo() gives me an error that compareTo() is undefined for type T. how can i get around this, or can i not use compareTo with a generic type T? |
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These two statements make me wonder if you understand that Eclipse uses it's own compiler, not the Sun SDK, and that the JRE used to run Eclipse in, the JRE used to launch your projects in, and the version of the compiler, are all separately configurable, sometimes with unusual results. It's possible to set it up so that, for example, it's ... |
A set of Comparators could be a solution too, but I don't see any added value in implementing these in my case. What I am trying to achieve is to create sets of ranges to which assignment values are attached. Then, if a parameter falls within a range, the corresponding assignment value is returned. The "compare" issue is to sort those ... |
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Hi, I was trying to call collections.sort for a List and I got a warning in eclipse. My code was something like this. List list = new ArrayList(); /* some code for poluating the list */ Collections.sort(list); On the above line I got the following warning in eclipse: Type safety: Unchecked invocation sort (List) of the generic method sort(List) of Type ... |
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