EQUALSVERIFIER | error exclusion guidelines for the release normal jar framework
EQUALSVERIFIER | error exclusion guidelines for the release normal jar framework
# Outline
EQUALSVERIFIER is a tool for simplifying the Java and HashCode method testing.It can verify whether the Equals and HashCode methods meet the rules of the contract and can find potential problems.This article aims to provide an error exclusion guide to help developers using Equalsverifier solve common problems.
# 1: Equals and HashCode methods are not being Override
When testing using EQUALSVERIFIER, if the Equals and HashCode methods in the class are not correctly override, there will be problems.Before writing a test case, make sure that the corresponding class has Override's Equals and HashCode methods.The following is an example class:
public class Person {
private String name;
private int age;
// Constructors, getters, and setters...
// Equals and Hashcode methods are not being override.
}
To solve this problem, we need to correctly rewrite the Equals and HashCode methods in the class:
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
Person other = (Person) obj;
return Objects.equals(name, other.name) && age == other.age;
}
@Override
public int hashCode() {
return Objects.hash(name, age);
}
# 2: Tostring method is not generated correctly
EQUALSVERIFIER also requires correct Override Tostring methods.If the Tostring method does not meet the rules of the contract, it may lead to the failure of Equalsverifier's testing.The following is a sample class and its tostring method that has not been generated correctly:
public class Person {
private String name;
private int age;
// Constructors, getters, and setters...
@Override
public String toString() {
return "Person@" + Integer.toHexString(hashCode());
}
}
To solve this problem, we need to correctly generate the TOSTRING method in the class:
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
# 3: The field does not correctly generate EQUALS and HashCode methods
In some cases, Equalsverifier may not be able to correctly detect the class fields, resulting in errors in the Equals and HashCode methods.This is usually caused by the proper definition of the field as Private or Final.The following is a sample class and the field definition caused by errors:
public class Person {
public String name;
public final int age;
// Constructors, getters, and setters...
// Equals and Hashcode methods error generation
}
To solve this problem, we need to define the field as Private or Final:
public class Person {
private String name;
private final int age;
// Constructors, getters, and setters...
// Equals and Hashcode methods correctly generate
}
# 4: The compulsory field is not included in the comparison of the EQUALS method
If the comparison of the EQUALS method does not include mandatory fields, Equalsverifier may have an error result.The following is an example class, where the mandatory field is not correctly compared:
public class Person {
private String name;
private final int age;
// Constructors, getters, and setters...
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
Person other = (Person) obj;
return Objects.equals(name, other.name);
}
@Override
public int hashCode() {
return Objects.hash(name);
}
}
To solve this problem, we need to compare the compulsory fields in the EQUALS method:
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
Person other = (Person) obj;
return Objects.equals(name, other.name) && age == other.age;
}
# Question 5: Equalsverifier test failure
If it is not successful through the EQUALSVERIFIER test, it may be caused by other factors.In this case, it is best to check whether the class definition is correct, and whether the Equals and HashCode methods meet the rules of the contract.
The following is a test example of the use of EQUALSVERIFIER:
public class PersonTest {
@Test
public void testEqualsAndHashCode() {
EqualsVerifier.forClass(Person.class)
.verify();
}
}
# in conclusion
This article provides common solutions to the EQUALSVERIFIER problem.By following these suggestions and correctly Override Equals, HashCode, and Tostring methods, you can use Equalsverifier more efficiently and discover potential problems.
I hope this article can help you better understand Equalsverifier and solve common problems smoothly.If you have other questions, please check with Equalsverifier's documentation or seek help from other related resources.
