I'll try to explain my problem as clear as possible :). I am using PropertyChangeSupport to notify registered views for changes in the properties. One of the property is an object which properties are changed every view seconds. I don't want to create for this particular object new instance every time it is being updated (for the propert...
I have a bunch of class who implement a common interface : Command. And this bunch of class goes to a Map. To get the Map working correctly, I need to each class who implements Command to override the Object.equals(Object other) method. it's fine. But i whould like to force the overriding of equals. => Have a compilation error when ...
I noticed in the source code for HashMap it lists the equals method as final. Why is it that when I override it I do not get a compile error? public class Test extends HashMap<Object, Object> { @Override public boolean equals(Object o) { return false; } } Java HashMap equals method: public final boolean equals(O...
I have the following class which contains only one field i. Access to this field is guarded by the lock of the object ("this"). When implementing equals() I need to lock this instance (a) and the other (b). If thread 1 calls a.equals(b) and at the same time thread 2 calls b.equals(a), the locking order is reverse in the two implementatio...
I've got an app in Google App Engine that was working fine. I realized that one on of my JDO-enhanced objects that I forgot to implement equals and hashCode (I need to use the object in a set). So I did. I didn't really do anything special in these implementations, in fact I just used Eclipse to generate them. Like so: @PrimaryKey @Pers...
i switched lecturers today and he stated using a weird code too me. he says its better. when i asked why, he asnwered "because it is!" so much for that. so heres an example: if (o1.equals(o2)) { System.out.println("Both integer objects are the same"); } instead of what im used too: if (o1 == o2) { System.out.println("Both inte...
Hi all, I have a Dictionary which I am comparing to another Dictionary (variables typed as IDictionary). Doing d1.Equals(d2) yeilds false. Writing my own code below yields true. Both are System.Collections.Generic.Dictionary. Am I missing something or does Dictionary not have an Equals implementation that compares keys/values? priv...
Hello everybody, The following code in C# doesn't work: int iValue = 0; double dValue = 0.0; bool isEqual = iValue.Equals(dValue); So, the question: what's the best way to compare Double and Int? -- Best Regards, Murat ...
I have had a few problems getting this right, so I wanted to ask if anyone has any feedback on whether this is an efficient way to implement the Equals method and equality/inequality operators for a custom immutable class. These operators are called very frequently by my program, so I want to make sure I get them right. class MyObj { ...
I recently was introduced to a large codebase and noticed all string comparisons are done using String.Equals() instead of ==. What's the reason for this, do you think? ...
I have implemented abstract generic provider for notification bunch of generic listeners E, descendants have to override notifyListener(E) with specific notification code. For backing list of listeners I choose WeakHashMap<K,V>. Listeners must be held as weak references: abstract public class NotificationProvider<E> { private Map<E...
So, I have an interface with a bunch of methods that need to be implemented, the method names are irrelevant. The objects that implement this interface are often put into collections, and also have a special toString() format that I want them to use. So, I thought it would be convenient to put hashCode(), equals(), and toString() into ...
What's the most compact code to compare three objects for (semantic) equality using Java? I have a business rule that the objects must be unique i.e. A is different to B, A is different to C and B is different to C. Assume that the objects are all of the same class and have correctly overridden equals and hashCode methods. A slight wrin...
Hi, I am trying to create a "KeySet" to modify UIElement behaviour. The idea is to create a special function if, eg. the user clicks on an element while holding a. Or ctrl+a. My approach so far, first lets create a container for all possible modifiers. If I would simply allow a single key, it would be no problem. I could use a simple D...
I'm working on a C# project for which, until now, I've used immutable objects and factories to ensure that objects of type Foo can always be compared for equality with ==. Foo objects can't be changed once created, and the factory always returns the same object for a given set of arguments. This works great, and throughout the code base ...
I can't figure out what's going wrong here. This test fails: @Test public void testSimpleCase() { assertTrue(JGraphtUtilities.graphEquality(ChooseRootTest.generateSimpleCaseGraph(), ChooseRootTest.generateSimpleCaseGraph())); } public static <V, E> boolean graphEquality(Graph<V, E> g0, Graph<V, E> g1) { boolean result = ...
In this file, in the function cross_from_below(x, threshold), there is a line that says threshold = threshold. What's the point of this line? Does this do something differently than if this command weren't there? ...
Whenever I use equals() method with two different StringBuffer objects, I get the result as false, but when I use equals() method with two different String objects, I get the result as true. Why? String s=new String("434"); String s1=new String("434"); System.out.println(s.equals(s1));//true StringBuffer s=new StringBuf...
Hello $mostamazingforumforfastanswersever. I have a quick silly question; what is the best way to write this : if ($curpageurl == "www.mysite.com/this" || "www.mysite.com/this/") { echo 'this is the this page'; } and if it isn't, then I need to call while (isset($somevariable) { echo '$somevariable'; } and if that variable isn'...
I want to put State objects (which are HashMaps with Character as key and State as Value into an ArrayList named allStates. Should I override the equals and hashCode methods here? Why? How? This code is for the Automaton and State classes I've built so far: class State extends HashMap<Character, State>{ boolean isFinal; boolean isIni...