*/ class People{ private String name; private int age; public People(String name,int age) { this.name = name; this.age = age; } public void setAge(int age){ this.age = age; } @Override public int hashCode() { // TODO Auto-generated method stub return name.hashCode()*37+age; ...
If a class is immutable and the cost of computing the hash code is significant, you might consider caching the hash code in the object rather than recalculating it each time it is requested. // Lazily initialized, cached hashCode privatevolatileinthashCode; // (See Item 71) @Override public ...
publicclassUser{privatelongid;privateString name;privateString email;// standard getters/setters/constructors@OverridepublicinthashCode(){return1; }@Overridepublicbooleanequals(Object o){if(this== o)returntrue;if(o ==null)returnfalse;if(this.getClass() != o.getClass())returnfalse;Useruser=(Us...
@EqualsAndHashCode,@Getter/@Setterand@RequiredArgsConstructortogether: In other words,@Datageneratesallthe boilerplate that is normally associated with simple POJOs (Plain Old Java Objects) and beans: getters for all fields, setters for all non-final fields, and appropriatetoString,equalsandhashCodeimp...
@OverridepublicinthashCode(){returnObjects.hash(title, topic_id, raw, category, target_recipients, archetype, created_at); } 如果你根据使用的是 Apache 的 Commons 生成的话,结果有所不同。 可以在 IDE 中自行研究下。 需要注意的是,在 hashCode 中,你可能会看到数字 17,31,37。
department = department; } @Override public int hashCode() { final int PRIME = 31; return new HashCodeBuilder(getId()%2==0?getId()+1:getId(), PRIME). toHashCode(); } @Override public boolean equals(Object o) { if (o == null) return false; if (o == this) return true; if (...
1.You must override hashCode in every class that overrides equals. 如果一个类实现了equals方法却没有实现hashCode方法,那么将这个对象A放入HashMap中,然后new一个与A相等的对象B,在HashMap中查找B,返回值将是null,因为没有实现hashCode方法,导致相等的两个对象返回的hash值不同(因为A==B为false)。
*/privatestaticclassPerson{intage;Stringname;publicPerson(Stringname,intage){this.name=name;this.age=age;}publicStringtoString(){returnname+" - "+age;}/*** @desc 覆盖equals方法*/@Overridepublicbooleanequals(Objectobj){if(obj==null){returnfalse;}//如果是同一个对象返回true,反之返回falseif(...
import java.io.Serializable; import java.util.Objects; @Data @AllArgsConstructor @NoArgsConstructor class User implements Serializable { int age; // 年龄 String name; // 姓名 double money;// 工资 // 重新equals方法 @Override public boolean equals(Object o) { ...
面试常问的重写(Override)和重载(Overload),你都懂了吗? 重写(Override)重写是子类对父类的允许访问的方法的实现过程进行重新编写, 返回值和形参都不能改变。即外壳不变,核心重写! 重写的好处,在于子类可以根据自身需要,定义特定于自己的行… 程序媛柚子 写时复制(Copy-On-Write)在Java中是如何被应用的吗? 前...