public class Person {

    // fields
    private int weight;
    private int age;
    private String name;
    private String pesel;

    // override equals
    @Override
    public boolean equals(Object obj){
        if(obj == null)
            return false;
        else if(obj instanceof Person) {
            Person other = (Person) obj;
            return
                    pesel.equals(other.pesel);
        }
        else
        return false;
    }
    // override hashCode
    @Override
    public int hashCode(){
        return pesel.hashCode();
    }
    // override toString
    @Override
    public String toString(){
        return "Imie: " + name + ", wiek: " + age + ", waga: " + weight + ", PESEL: " + pesel;
    }

    // constructors
    public Person(){};
    public Person(int weight, int age, String name, String pesel){
        this.weight = weight;
        this.age = age;
        this.name = name;
        this.pesel = pesel;
    }

    // getters
    public int getAge(){
        return age;
    }
    public String getPesel(){
        return pesel;
    }
    public int getWeight(){
        return weight;
    }
    public String getName(){
        return name;
    }

    // setters
    public void setAge(int age){
        this.age = age;
    }
    public void setPesel(String pesel){
        this.pesel = pesel;
    }
    public void setWeight(int weight){
        this.weight = weight;
    }
    public void setName(String name){
        this.name = name;
    }
}