[JAVA] Lombok memo

What is Lombok

--A library that automatically generates frequently used code such as getter / setter and constructor in Java --For example, if you annotate a class with @Getter, it will automatically generate getters for the fields in the class. --The official page is here

environment

• openjdk 12.0.1
• IntelliJ IDEA CE 2019.1
• lombok 1.18.8

Make Lombok available

Settings in IntelliJ

--Install the lombok plugin --Preference-> Plugins-> Search for lombok in MarketPlace and install --Enable annotation processing -Check Enable annotation processing in Preferences-> Build, Execution, Deployment-> Compiler-> Annotation Processors

build.gradle settings

Add the following to dependencies in build.gradle

build.gradle

compileOnly 'org.projectlombok:lombok:1.18.8'
annotationProcessor 'org.projectlombok:lombok:1.18.8'

Check the code generated by lombok

--You can see the code generated by lombok by running delombok --When checking from the command line,

java -jar <lombok.jar path> delombok -p <Annotated class path>

Annotation

@Getter / @Setter

--Automatically generate getter / setter for the fields included in the given class

Grantor

import lombok.Getter;
import lombok.Setter;

import java.util.List;

@Getter
@Setter
public class Human {
    private int age;
    private String name;
    private List<String> hobby;
}

Generated class

import java.util.List;

public class Human {
    private int age;
    private String name;
    private List<String> hobby;

    @java.lang.SuppressWarnings("all")
    public int getAge() {
        return this.age;
    }

    @java.lang.SuppressWarnings("all")
    public String getName() {
        return this.name;
    }

    @java.lang.SuppressWarnings("all")
    public List<String> getHobby() {
        return this.hobby;
    }

    @java.lang.SuppressWarnings("all")
    public void setAge(final int age) {
        this.age = age;
    }

    @java.lang.SuppressWarnings("all")
    public void setName(final String name) {
        this.name = name;
    }

    @java.lang.SuppressWarnings("all")
    public void setHobby(final List<String> hobby) {
        this.hobby = hobby;
    }
}

@ToString

--Automatically generate toString () method

Grantor

import lombok.ToString;

import java.util.List;

@ToString
public class Human {
    private int age;
    private String name;
    private List<String> hobby;
}

Generated class

import java.util.List;

public class Human {
    private int age;
    private String name;
    private List<String> hobby;

    @java.lang.Override
    @java.lang.SuppressWarnings("all")
    public java.lang.String toString() {
        return "Human(age=" + this.age + ", name=" + this.name + ", hobby=" + this.hobby + ")";
    }
}

@NoArgsConstructor / @RequiredArgsConstructor / @AllArgsConstructor

--@NoArgsConstructor: Automatically generate a no-argument constructor --@RequiredArgsConstructor: Automatically generate a constructor that takes a field with final as an argument --@AllArgsConstructor: Automatically generate a constructor with all fields as arguments

Grantor(@AllArgsConstructor)

import lombok.AllArgsConstructor;

import java.util.List;

@AllArgsConstructor
public class Human {
    private int age;
    private final String name;
    private List<String> hobby;
}

Generated class

import java.util.List;

public class Human {
    private int age;
    private final String name;
    private List<String> hobby;

    @java.lang.SuppressWarnings("all")
    public Human(final int age, final String name, final List<String> hobby) {
        this.age = age;
        this.name = name;
        this.hobby = hobby;
    }
}

@Data

--Same effect as adding the following annotation

• @Getter / @Setter
• @ToString
• @EqualsAndHashCode
• @RequiredArgsConstructor

@Value

--Immutable version of @Data --Make all fields private and final --setter is not generated

@Builder

--Automatically generate Builder class

Grantor

import lombok.Builder;

import java.util.List;

@Builder
public class Human {
    private int age;
    private final String name;
    private List<String> hobby;
}

Side to use

import java.util.Arrays;
import java.util.List;

public class Main {
  public static void main(String[] args) {
    List<String> hobby = Arrays.asList("Futsal", "diet", "reading");
    Human human = new Human.HumanBuilder().age(20).name("Name Taro").hobby(hobby).build();
    System.out.println(human);
  }
}

Generated class

import java.util.List;

public class Human {
    private int age;
    private final String name;
    private List<String> hobby;

    @java.lang.SuppressWarnings("all")
    Human(final int age, final String name, final List<String> hobby) {
        this.age = age;
        this.name = name;
        this.hobby = hobby;
    }


    @java.lang.SuppressWarnings("all")
    public static class HumanBuilder {
        @java.lang.SuppressWarnings("all")
        private int age;
        @java.lang.SuppressWarnings("all")
        private String name;
        @java.lang.SuppressWarnings("all")
        private List<String> hobby;

        @java.lang.SuppressWarnings("all")
        HumanBuilder() {
        }

        @java.lang.SuppressWarnings("all")
        public HumanBuilder age(final int age) {
            this.age = age;
            return this;
        }

        @java.lang.SuppressWarnings("all")
        public HumanBuilder name(final String name) {
            this.name = name;
            return this;
        }

        @java.lang.SuppressWarnings("all")
        public HumanBuilder hobby(final List<String> hobby) {
            this.hobby = hobby;
            return this;
        }

        @java.lang.SuppressWarnings("all")
        public Human build() {
            return new Human(age, name, hobby);
        }

        @java.lang.Override
        @java.lang.SuppressWarnings("all")
        public java.lang.String toString() {
            return "Human.HumanBuilder(age=" + this.age + ", name=" + this.name + ", hobby=" + this.hobby + ")";
        }
    }

    @java.lang.SuppressWarnings("all")
    public static HumanBuilder builder() {
        return new HumanBuilder();
    }
}

@NonNull

--If you give it to a class field or method argument, it will automatically check for null.

@EqualsAndHashCode

--ʻEquals () , hashCode () `method is automatically generated

@Log

--Automatically generate Logger with the name log

@Code generated when Slf4j is added

private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(LogExample.class);

--Supports various libraries such as Slf4j, Log4j --Plan to study Logger separately

var / val

--The type can be inferred automatically when a variable is declared. It seems that it will not be used because it was implemented as standard in JDK10 or later