equals

问题 I was reading the paragraph quoted below from an article entitled- Java theory and practice: Hashing it out - Defining hashCode() and equals() effectively and correctly Defining equality The Object class has two methods for making inferences about an object's identity: equals() and hashCode(). In general, if you override one of these methods, you must override both, as there are important relationships between them that must be maintained. In particular, if two objects are equal according to

问题 I was reading the paragraph quoted below from an article entitled- Java theory and practice: Hashing it out - Defining hashCode() and equals() effectively and correctly Defining equality The Object class has two methods for making inferences about an object's identity: equals() and hashCode(). In general, if you override one of these methods, you must override both, as there are important relationships between them that must be maintained. In particular, if two objects are equal according to

问题 I want to compare two ArrayList of string arrays. List<String[]> list1 = new ArrayList<String[]>; List<String[]> list2 = new ArrayList<String[]>; list1.equals(list2); This will return false because equals method in ArrayList will do equals on the element. ListIterator<E> e1 = listIterator(); ListIterator<?> e2 = ((List<?>) o).listIterator(); while (e1.hasNext() && e2.hasNext()) { E o1 = e1.next(); Object o2 = e2.next(); if (!(o1==null ? o2==null : o1.equals(o2))) return false; } return !(e1

问题 I am in big trouble, created a hashMap and inserted two values with same key using StringBuilder as a key of map. Now, while trying to retrieve the data using StringBuilder object is working fine, but in other case its fails to return any value. I have listed three cases in the below given code, ` class MainClass { public static void main(String[] args) { MainClass m = new MainClass(); StringBuilder sb = new StringBuilder("sb"); StringBuilder sb1 = new StringBuilder("sb"); Map<StringBuilder,

问题 I am in big trouble, created a hashMap and inserted two values with same key using StringBuilder as a key of map. Now, while trying to retrieve the data using StringBuilder object is working fine, but in other case its fails to return any value. I have listed three cases in the below given code, ` class MainClass { public static void main(String[] args) { MainClass m = new MainClass(); StringBuilder sb = new StringBuilder("sb"); StringBuilder sb1 = new StringBuilder("sb"); Map<StringBuilder,

问题 I am in big trouble, created a hashMap and inserted two values with same key using StringBuilder as a key of map. Now, while trying to retrieve the data using StringBuilder object is working fine, but in other case its fails to return any value. I have listed three cases in the below given code, ` class MainClass { public static void main(String[] args) { MainClass m = new MainClass(); StringBuilder sb = new StringBuilder("sb"); StringBuilder sb1 = new StringBuilder("sb"); Map<StringBuilder,

问题 I think I can't see the forest for the trees... How do I test for equality (not identity) of all elements recursively in a List of String arrays? Here's a minimal example: List<String[]> left = new ArrayList<>(); left.add(new String[]{"one", "two"}); List<String[]> right = new ArrayList<>(); right.add(new String[]{"one", "two"}); System.out.println(left.equals(right) ? "Yeah!" : "This is not what I want."); I want to use this in unit tests. A bit more context: I have a class that holds

问题 I am using a priorityQueue to implement BFS. I want to maintain the insertion order in the case of equal priority while inserting and also after poping. I overrode the equals method as shown below and the insertion order is maintained as expected while inserting. But, once I do a remove or poll, the order of the elements changes. How can I maintain the insertion order even on poll? class Cell implements Comparable<Cell>{ int v; int dis; public Cell(int v, int dis) { this.v = v; this.dis = dis

问题 This question already has answers here : How equals() method works (8 answers) What issues should be considered when overriding equals and hashCode in Java? (11 answers) Closed 3 years ago . class Dog{ int height; int weight; String name; } public class DogTest { public static void main(String[] args) { Dog one = new Dog(); one.height=4; one.name="fudo"; one.weight =2; Dog two = new Dog(); two.height=4; two.name="fudo"; two.weight =2; if (one.equals(two)){ System.out.println("True"); } else{

问题 I don't get what exactly means the equal sign in Elixir. What is unclear is that it looks like a mix between assignment and a pattern matching operation. iex(1)> x=4 4 iex(2)> y=5 5 iex(3)> 3=y ** (MatchError) no match of right hand side value: 5 iex(3)> y=3 3 iex(4)> y=x 4 I understand that in Elixir, the equals operator means to match the left side of the = sign to the the right side. First two lines make sense to me. x and y are unbound variables, hence they could match anything. They are