使用Apache Commons Lang包重写hashCode() 和equals()方法
Apache Commons 包提供了两个非常优秀的类来生成hashCode()和equals()方法。看下面的程序。
- import org.apache.commons.lang3.builder.EqualsBuilder;
- import org.apache.commons.lang3.builder.HashCodeBuilder;
- public class Employee
- {
- private Integer id;
- private String firstname;
- private String lastName;
- private String department;
- public Integer getId() {
- return id;
- }
- public void setId(Integer id) {
- this.id = id;
- }
- public String getFirstname() {
- return firstname;
- }
- public void setFirstname(String firstname) {
- this.firstname = firstname;
- }
- public String getLastName() {
- return lastName;
- }
- public void setLastName(String lastName) {
- this.lastName = lastName;
- }
- public String getDepartment() {
- return department;
- }
- public void setDepartment(String department) {
- this.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 (o.getClass() != getClass())
- return false;
- Employee e = (Employee) o;
- return new EqualsBuilder().
- append(getId(), e.getId()).
- isEquals();
- }
- }
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