Lombok - @ToString

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Lombok - @ToString

A class definition annotated with @ToString lets Lombok generate the toString() method implementation. By default, it'll print the class name, along with each field, in order and separated by commas.

Let's take a look at the following example which shows the basic usage of this annotation.

package nl.emsnsoftware.entity;

import lombok.*;

import java.time.LocalDate;

@NoArgsConstructor()
@ToString
public class Car {
    String licensePlate;
    String brand;
    LocalDate manufacturingDate;
    boolean inUse;
    static int count;
}

And the generated code:

package nl.emsnsoftware.entity;

import java.time.LocalDate;

public class Car {
    String licensePlate;
    String brand;
    LocalDate manufacturingDate;
    boolean inUse;
    static int count;

    public Car() {
    }

    public String toString() {
        return "Car(licensePlate=" + this.licensePlate + ", brand=" + this.brand + ", manufacturingDate=" + this.manufacturingDate + ", inUse=" + this.inUse + ")";
    }
}

From this example, we can notice that Lombok generated the toString method including the name of the class plus all non-static fields of the class.

Now let's say we do not want to include all non-static fields in the toString method, what can we do? Lombok provides way for achiving this.

  1. By annotating these fields with @ToString.Exclude.
package nl.emsnsoftware.entity;

import lombok.*;

import java.time.LocalDate;

@NoArgsConstructor()
@ToString
public class Car {
    String licensePlate;
    String brand;
    @ToString.Exclude
    LocalDate manufacturingDate;
    @ToString.Exclude
    boolean inUse;
    static int count;
}
package nl.emsnsoftware.entity;

import java.time.LocalDate;

public class Car {
    String licensePlate;
    String brand;
    LocalDate manufacturingDate;
    boolean inUse;
    static int count;

    public Car() {
    }

    public String toString() {
        return "Car(licensePlate=" + this.licensePlate + ", brand=" + this.brand + ")";
    }
}
  1. Or adding @ToString(onlyExplicitlyIncluded = true) to the class definition and annotating the required fields with @ToString.Include.
package nl.emsnsoftware.entity;

import lombok.*;

import java.time.LocalDate;

@NoArgsConstructor()
@ToString(onlyExplicitlyIncluded = true)
public class Car {
    @ToString.Include
    String licensePlate;
    @ToString.Include
    String brand;
    LocalDate manufacturingDate;
    boolean inUse;
    static int count;
}
package nl.emsnsoftware.entity;

import java.time.LocalDate;

public class Car {
    String licensePlate;
    String brand;
    LocalDate manufacturingDate;
    boolean inUse;
    static int count;

    public Car() {
    }

    public String toString() {
        return "Car(licensePlate=" + this.licensePlate + ", brand=" + this.brand + ")";
    }
}

Thank you for reading my blog. Please make sure to check out the other Lombok annotations articles by visiting the Lombok section of my blog.

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