equals

问题 data: function( elem, name, data ) { if ( !jQuery.acceptData( elem ) ) { return; } elem = elem == window ? windowData : elem; Copied directly from the jQuery source. Why is it not safe to use elem === window ? Why does jQuery use type coercion on the window object? It would appear that in IE there's an issue with top top == window // true top === window // false 回答1: See here for why checking againts the window object with === is unsafe in IE. I think the root cause is that IE is closely

问题 I believe I read somewhere people generating equals / hashcode / toString methods during compile time (using APT) by identifying which fields should be part of the hash / equality test. I couldn't find anything like that on the web (I might have dreamed it ?) ... That could be done like that : public class Person { @Id @GeneratedValue private Integer id; @Identity private String firstName, lastName; @Identity private Date dateOfBirth; //... } For an entity (so we want to exlude some fields,

问题 If I have a map and an object as map key, are the default hash and equals methods enough? class EventInfo{ private String name; private Map<String, Integer> info } Then I want to create a map: Map<EventInfo, String> map = new HashMap<EventInfo, String>(); Do I have to explicitly implement hashCode() and equals()? Thanks. 回答1: Yes, you do. HashMap s work by computing the hash code of the key and using that as a base point. If the hashCode function isn't overriden (by you), then it will use the

问题 I have an object called FormObject that contains two ArrayLists - oldBooks and newBooks - both of which contain Book objects. oldBooks is allowed to contain duplicate Book objects newBooks is not allowed to contain duplicate Book objects within itself and cannot include any duplicates of Book objects in the oldBooks list. The definition of a duplicate Book is complex and I can't override the equals method as the definition is not universal across all uses of the Book object. I plan to have a

问题 I have an object called FormObject that contains two ArrayLists - oldBooks and newBooks - both of which contain Book objects. oldBooks is allowed to contain duplicate Book objects newBooks is not allowed to contain duplicate Book objects within itself and cannot include any duplicates of Book objects in the oldBooks list. The definition of a duplicate Book is complex and I can't override the equals method as the definition is not universal across all uses of the Book object. I plan to have a

问题 Here is my debate, the problem is solved, but I cant figure out why the method used on css-tricks.com didnt work. The only reason I can assume it didnt work was because my columns are responsive. Here is a jsfiddle of the problem. Solution 1 Nicolas Gallagher Method Wont work, why. Because my client could at any time add another box (tell me to add another box, or minus a box). So I need my code to be responsive. I took the css off btw, but if you can look and tell me how to make this work,

问题 Hi I am running a maven test using maven 3.0.3 with hibernate 4.0.0 Final release and spring 3.1 on jdk7 update 2. I get the following error. Caused by: java.lang.VerifyError: Expecting a stackmap frame at branch target 63 in method ${myDomainClass}.equals(Ljava/lang/Object;)Z at offset 24 at java.lang.Class.getDeclaredMethods0(Native Method) at java.lang.Class.privateGetDeclaredMethods(Class.java:2442) at java.lang.Class.getDeclaredMethods(Class.java:1808) at org.hibernate.property

问题 Is there any equality predicate function in ImageMagick library? I want to compare two images and find whether they are the exactly same (all colors of the pixels are the same) or have any differences. I’ve looked around, but it seems not to have a such function. Should I write the function using pixel iterators by myself? 回答1: ImageMagick provides the compare function to properly compare images. Checking the md5 checksum of two images is not the correct approach, since some image formats (e

问题 This question already has answers here : Closed 9 years ago . Possible Duplicate: Comparing StringBuffer content with equals StringBuffer s1= new StringBuffer("Test"); StringBuffer s2 = new StringBuffer("Test"); if(s1.equals(s2)) { System.out.println("True"); } else { System.out.println("False"); } Why does that code print "False"? 回答1: StringBuffer does not override the Object.equals method, so it is not performing a string comparison. Instead it is performing a direct object comparison.

问题 Based on various bad experiences my rule of thumb as a Java programmer is to only implement equals() and hashCode() on immutable objects, where two instances of the object really are interchangeable. Basically I want to avoid situations like the HashMap key problem in that link, or like the following: Get a thing with a certain identity. Modify it. Add it to a set. (later) Get another thing with the same identity. Modify it. Add it to the same set. Fail to notice that this add doesn't