equals

Why two objects with the same hashcode are not necessarily equals? [duplicate]

由 拥有回忆 提交于 2019-12-16 18:05:22
问题 This question already has answers here : What issues should be considered when overriding equals and hashCode in Java? (11 answers) Closed 3 years ago . Currently I drilled into the JSE source code for fun. From some tutorials I found a principle two equals objects (i.e. as to object a and b a.equals(b) returns true) must have the same hashcode, on the other hand, two objects with the same hashcode are not necessarily equals . According to the HashTable source code of Java API (http:/

hashCode与equals的区别与联系

由 旧街凉风 提交于 2019-12-14 23:22:19
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 一、equals方法的作用 1、 默认情况（没有覆盖equals方法）下equals方法都是调用Object类的equals方法，而Object的equals方法主要用于判断对象的内存地址引用是不是同一个地址（是不是同一个对象）。 2 、要是类中覆盖了equals方法，那么就要根据具体的代码来确定equals方法的作用了，覆盖后一般都是通过对象的内容是否相等来判断对象是否相等。 没有覆盖equals方法代码如下： [java] view plain copy //学生类 public class Student { private int age; private String name; public Student() { } public Student( int age, String name) { super (); this .age = age; this .name = name; } public int getAge() { return age; } public String getName() { return name; } public void setAge( int age) { this .age = age; } public void setName(String

What is the need to override equals method in String class? [closed]

由 。_饼干妹妹 提交于 2019-12-14 04:23:49
问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 2 years ago . The reason behind asking the question is that String in Java are interned So String s1 = "Hello"; String s2 = "Hello"; Both s1 and s2 will point to same object in the memory. Two different objects will not be created. s1.equals(s2) should return true and it does. Now In java documentation it says

Comparing java Strings with == [duplicate]

由 限于喜欢 提交于 2019-12-14 03:30:18
问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Java String.equals versus == Is it possible to compare Java Strings using == operator? Why do I often see, that equals() method is used instead? Is it because when comparing with literal Strings (like "Hello") using == doesn't imply calling equals()? 回答1: there is no custom operator overloading in java. [so you cannot overload it to call equals()] the equals() ensures you check if 2 Objects are identical,while =

hascode and equals methods not overridden - How the put and get will work?

由 ε祈祈猫儿з 提交于 2019-12-14 02:46:10
问题 I have a class Student and Marks. I am using Student Object as Key for HashMap and Marks as Value. If I don't override hashMap and equals, It still works fine. i. Can someone please explain how does it internally works on it if not overriding both equals() and hashcode() ii. what If I override only hashcode() iii.what If I override only equals() class Student { String name; public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; }

Implementing equals() with JDK Dynamic Proxies

由 十年热恋 提交于 2019-12-14 00:57:45
问题 For the first time ever, I have to implement my own proxy classes using the standard JDK Dynamic Proxy. It works fairly well, except for one detail: the equals(...) method. Let's assume that we have a simple Interface like this, which we want to proxy: public interface MyInterface { public String getID(); public void setID(String id); } ... and our implementation looks like this (standard Java Bean with generated hashCode() and equals ): public class MyImplementation implements MyInterface {

Color is equal to another color, Java [closed]

由 你离开我真会死。 提交于 2019-12-13 23:51:10
问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 6 years ago . Okay the color I have set in the variable C is equal to the variable in coal1, but when put through an if statement it comes back that they are not equal. I've debugged it with print lines and the result is weird

How do you generate a random number with equal probability using Math.random() in Java [duplicate]

由 泪湿孤枕 提交于 2019-12-13 19:16:01
问题 This question already has answers here : How do I generate random integers within a specific range in Java? (65 answers) Closed 6 years ago . I'm currently working through an exercise where I am required to generate a random number which can be one of 4 values. (note I'm only allowed to use Math.random()) 0 1 2 or 3 Currently I am using this: randno = (int) (Math.random()*4); // range 0-3 However, the outcome MUST have equal probability. My tests so far (although the method is lacking) shows

Implement equals with Set

由 不羁的心 提交于 2019-12-13 15:54:40
问题 I have this class: private static class ClassA{ int id; String name; public ClassA(int id, String name){ this.id= id; this.name = name; } @Override public boolean equals(Object o) { return ((ClassA)o).name.equals(this.name); } } Why this main is printing 2 elements if I am overwriting the method equals in ClassA to compare only the name? public static void main(String[] args){ ClassA myObject = new ClassA(1, "testing 1 2 3"); ClassA myObject2 = new ClassA(2, "testing 1 2 3"); Set<ClassA> set

Examining associated objects in equals() [closed]

由 拜拜、爱过 提交于 2019-12-13 09:14:07
问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 5 years ago . Standard object modelling identifies attributes, aggregates and associations of objects. You must conform to several requirements when implementing the equals() method of a class. There is plenty of advice available on how to write this method, including pitfalls to avoid.
订阅 equals