equals

问题 Almost every time I want to check object's equality to null I use the normal equality check operation if (obj == null) Recently I noticed that I'm using the Object.Equals() more often if (Object.Equals(obj, null)) and while reading about null checking I fount this Is ReferenceEquals(null, obj) the same thing as null == obj? if (ReferenceEquals(null, obj)) Whats the difference? and where/when to use each one? plus I found that the last two checks look like the same according to their summary

问题 I have a class Output which basically contains a BitSet with overides on hashCode and equals. Then I have a HashSet of Outputs and I do the following operations : Set<Output> outputs = new HashSet<>(); Output o1 = new Output(); o1.flip(3); Output o2 = new Output(); o2.flip(1); o2.flip(3); outputs.add(o1); outputs.add(o2); If I do a print(outputs) I get [Output@5a1, Output@5a3] Now if I do o2.flip(1); I get [Output@5a3, Output@5a3] which of course, is the normal behavior of a Set, since the

问题 I need to make three equal height columns with varying amounts of content with rounded corners. the corners need an 8px border radius. I would prefer to accomplish this with pure CSS if possible. Right now my html looks like this: <div class="col-w"> <div class="col-h col-1"> <h2>About Us</h2> <p>Founded in 1995 in Atlanta, Georgia, The Creative Circus is an accredited, two-year, portfolio-building, educational program for the creative side of the Advertising, Interactive Development, Design

问题 I have to compare two strings such as INTU and IXTE and check if two or more of the characters are the same. With the previous two strings, I'd want to return true , since the I and the T are the same. Order of letters in the string ends up being irrelevant as each character can not appear in different positions in the string. It seems like there should be an easy way to do this. 回答1: look at similar_text() . The following code is untested but i think it would work as you want. $a = "INTU";

问题 I have read about the equals() method in java. I've heard that it compares based just on value. But then why is it returning false for my case below where the value is the same but the types are different? public class test { public static void main(String[] args) { String s1="compare"; StringBuffer s2=new StringBuffer("compare"); System.out.println(s1.equals(s2)); //false } } 回答1: A String instance cannot be equal to a StringBuffer instance. Look at the implementation : public boolean equals

问题 I cannot understand particular details of CharBuffer equals() method functioning. I don't understand this "considered independently of their starting positions" phrase: Two char buffers are equal if, and only if , They have the same element type, They have the same number of remaining elements, and The two sequences of remaining elements, considered independently of their starting positions , are pointwise equal. I studies these good examples - more examples, but I don't understand the idea.

问题 I have an array of objects that I want to compare to a target object. I want to return the number of objects that exactly match the target object. Here is my count method: public int countMatchingGhosts(Ghost target) { int count=0; for (int i=0;i<ghosts.length;i++){ if (ghosts[i].equals(target)); count++; } return count; And here is my equals method: public boolean equals(Ghost other){ if(this == other) return true; if( !(other instanceof Ghost) ) return false; Ghost p = (Ghost)other; if

问题 From MSDN documentation, it seems as both GetHashCode() and Equals() haven't been overriden in Bitmap. Neither have them been overriden in Image. So both classes are using the Object's version of them just compares references. I wasn't too convinced so I decided to fire up Reflector to check it out. It seems MSDN is correct in that matter. So, is there any special reason why MS guys wouldn't implement "comparison logic", at least for the Bitmap class? I find it is kinda acceptable for Image,

问题 I'm currently studying the Comparator interface and noticed that in the documentation for Comparator's equals method, it states Note that it is always safe not to override Object.equals(Object) I have checked the implementation for the default equals method in Object class So with the default implementation of equals method, it simply checks whether two instances points to the same object because this == obj tests for reference equality. But what happen if I have two instances of Comparator ,

问题 In this article, Eric Lippert suggests in point #9 that C# has "too much equality". He points out that there are 9 or 10 different methods or operators that can be overloaded to provide object equality. My first question is - if the Object.Equals(object) method is overridden, is it possible for the compiler to call any of the other equality operators like ==, !=, <=, etc. without code that expressly performs this operation? In C++, there is precedent for this behavior. The copy constructor