Immutable Class as Final

The immutable class has the property that once the object is created it cannot be updated. But if the class can be extended, then its method can be overridden to modify the existing data members later, in the below example, the addPrice method is overridden and now can be used to modify the data members as shown below.

package org.wesome.dsalgo;

import java.util.Objects;

public class Apple {
    String name;
    float price;

    public Apple(String name, float price) {
        this.name = name;
        this.price = price;
    }

    public String getName() {
        return name;
    }

    public float getPrice() {
        return price;
    }

    /*  add the new price to the existing price */
    public float addPrice(float price) {
        return this.price + price;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Apple apple = (Apple) o;
        return Float.compare(apple.price, price) == 0 && Objects.equals(name, apple.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(name, price);
    }
}

package org.wesome.dsalgo;

public class AppleExt extends Apple {

    public AppleExt(String name, float price) {
        super(name, price);
    }

    /*  override the method to update the data member variable */
    @Override
    public float addPrice(float price) {
        this.price = price;
        return this.price;
    }
}

package org.wesome.dsalgo;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

public class AppleTest {
    @Test
    public void finalFieldTest() {
        Apple apple = new AppleExt("Mcintosh", 1.1f);
        apple.addPrice(2.2f);
        Assertions.assertAll(() -> {
            Assertions.assertEquals("Mcintosh", apple.getName());
            Assertions.assertEquals(2.2f, apple.getPrice());
        });
    }
}

plugins {
    id 'java'
    id "io.freefair.lombok" version "6.2.0"
}

group = 'org.wesome'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = JavaVersion.VERSION_1_8

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

dependencies {
    testImplementation 'org.junit.jupiter:junit-jupiter:5.6.2'
}

test {
    useJUnitPlatform()
}