[英]How to build an object when we have inheritance relationship using lombok builder?
在我的項目中,我使用lombok來避免為一個類編寫getter和setter。 此外,我使用lombok.Builder來構建一個對象,而不是編寫新的Obeject(),然后設置所有的值。
但是當我們有繼承關系並且當我們想要使用lombok builder構建子對象時,我沒有得到父類的字段。
例如:
@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
@EqualsAndHashCode
public class Parent{
private String nationality;
.
.
// more columns
}
而Child類將是這樣的:
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public class Child extends Parent{
private String firstName;
private String lastName;
.
.
}
在我的測試類中,我需要構建子對象
public class Test{
public void testMethod(){
Child child = Child.builder()
.firstName("Rakesh")
.lastName("SS")
.nationality("some text")// I am not able to set nationality
.build();
}
}
請讓我知道,有沒有辦法在lombok中處理這種情況。
@Builder
無法確定您希望公開哪個Parent
字段。
將@Builder
放在類上時,只有在該類上顯式聲明的字段才會添加到*Builder
。
當@Builder
放置在靜態方法或構造函數上時,生成的*Builder
將為每個參數提供一個方法。
此外,如果您使用@Builder
那么可以安全地假設至少Child
是不可變的嗎?
我提供了兩個例子,一個是Parent
是可變的, Child
是不可變的,另一個是Parent
和Child
都是不可變的。
import static org.junit.Assert.*;
import lombok.Builder;
import lombok.EqualsAndHashCode;
import lombok.ToString;
import lombok.Value;
import lombok.experimental.NonFinal;
import org.junit.Test;
public class So32989562ValueTest {
@Value
@NonFinal
public static class Parent {
protected final String nationality;
}
@Value
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public static class Child extends Parent {
private final String firstName;
private final String lastName;
@Builder(toBuilder = true)
private Child(String nationality, String firstName, String lastName) {
super(nationality);
this.firstName = firstName;
this.lastName = lastName;
}
}
@Test
public void testChildBuilder() {
String expectedFirstName = "Jeff";
String expectedLastName = "Maxwell";
String expectedNationality = "USA";
Child result = Child.builder()
.firstName(expectedFirstName)
.lastName(expectedLastName)
.nationality(expectedNationality)
.build();
assertEquals(result.toString(), expectedFirstName, result.getFirstName());
assertEquals(result.toString(), expectedLastName, result.getLastName());
assertEquals(result.toString(), expectedNationality, result.getNationality());
}
}
import static org.junit.Assert.*;
import lombok.Builder;
import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.ToString;
import lombok.Value;
import org.junit.Test;
public class So32989562DataTest {
@Data
public static class Parent {
protected String nationality;
}
@Value
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public static class Child extends Parent {
private final String firstName;
private final String lastName;
@Builder(toBuilder = true)
private Child(String nationality, String firstName, String lastName) {
this.setNationality(nationality);
this.firstName = firstName;
this.lastName = lastName;
}
}
@Test
public void testChildBuilder() {
String expectedFirstName = "Jeff";
String expectedLastName = "Maxwell";
String expectedNationality = "USA";
Child result = Child.builder()
.firstName(expectedFirstName)
.lastName(expectedLastName)
.nationality(expectedNationality)
.build();
assertEquals(result.toString(), expectedFirstName, result.getFirstName());
assertEquals(result.toString(), expectedLastName, result.getLastName());
assertEquals(result.toString(), expectedNationality, result.getNationality());
}
}
以上解決方案有效,但需要太多的解決方法。 而且,子類和父類的任何更改都需要在任何地方更改構造函數參數。
Lombok針對Builder注釋面臨的繼承問題引入了版本:1.18.2的實驗性功能,可以使用@SuperBuilder注釋解決如下。
@SuperBuilder
public class ParentClass {
private final String a;
private final String b;
}
@SuperBuilder
public class ChildClass extends ParentClass{
private final String c;
}
現在,可以使用如下的Builder類(使用@Builder注釋無法實現)
ChildClass.builder().a("testA").b("testB").c("testC").build();
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