Sinflar va obyektlar

import java.util.ArrayList;
import java.util.List;

public class Jurnal {
    public static void main(String[] args) {
        Talaba t = new Talaba("Husanboy Qodirov", 25);

        t.ballQoshish(90);
        t.ballQoshish(85);
        t.ballQoshish(95);

        t.korsat();
    }
}

class Talaba {
    private final String ism;
    private final int yosh;
    private final List<Integer> ballar = new ArrayList<>();

    Talaba(String ism, int yosh) {
        this.ism = ism;
        this.yosh = yosh;
    }

    void ballQoshish(int ball) {
        ballar.add(ball);
    }

    double ortacha() {
        if (ballar.isEmpty()) {
            return 0;
        }
        int jami = 0;
        for (int b : ballar) {
            jami += b;
        }
        return (double) jami / ballar.size();
    }

    void korsat() {
        System.out.println(ism + ", " + yosh + " yosh");
        System.out.println("Baholar soni: " + ballar.size());
        System.out.println("O'rtacha: " + ortacha());
    }
}

public class ThisMisol {
    public static void main(String[] args) {
        Nuqta n = new Nuqta(3, 4);
        System.out.println(n.korsat());
        System.out.println(n.siljit(1, 1).korsat());
    }
}

class Nuqta {
    private final int x;
    private final int y;

    Nuqta(int x, int y) {
        this.x = x;          // maydon = parametr
        this.y = y;
    }

    Nuqta siljit(int dx, int dy) {
        return new Nuqta(this.x + dx, this.y + dy);
    }

    String korsat() {
        return "(" + x + ", " + y + ")";
    }
}

public class Bank {
    public static void main(String[] args) {
        Hisob h = new Hisob("Malika");

        h.qoshish(50000);
        h.qoshish(30000);
        h.yechish(20000);
        h.yechish(999999);

        System.out.println(h.egasi() + ": " + h.balans() + " so'm");
        System.out.println("Amallar soni: " + h.amallarSoni());
    }
}

class Hisob {
    private final String egasi;
    private long balans = 0;
    private int amallar = 0;

    Hisob(String egasi) {
        this.egasi = egasi;
    }

    String egasi() {
        return egasi;
    }

    long balans() {
        return balans;
    }

    int amallarSoni() {
        return amallar;
    }

    void qoshish(long miqdor) {
        if (miqdor <= 0) {
            throw new IllegalArgumentException("Miqdor musbat bo'lsin");
        }
        balans += miqdor;
        amallar++;
    }

    void yechish(long miqdor) {
        if (miqdor > balans) {
            System.out.println("Mablag' yetarli emas: " + miqdor);
            return;
        }
        balans -= miqdor;
        amallar++;
    }
}

public class Konstruktorlar {
    public static void main(String[] args) {
        System.out.println(new Kitob("Alpomish").tavsif());
        System.out.println(new Kitob("Alpomish", 1928).tavsif());
        System.out.println(new Kitob().tavsif());
    }
}

class Kitob {
    private final String nom;
    private final int yili;

    Kitob() {
        this("Noma'lum", 0);
    }

    Kitob(String nom) {
        this(nom, 0);
    }

    Kitob(String nom, int yili) {
        this.nom = nom;
        this.yili = yili;
    }

    String tavsif() {
        return yili == 0 ? nom + " (yili noma'lum)" : nom + " (" + yili + ")";
    }
}

public class ToStringMisol {
    public static void main(String[] args) {
        String sukut = new Oddiy().toString();

        System.out.println("Sukut, '@' gacha: "
                + sukut.substring(0, sukut.indexOf('@')));
        System.out.println("Qayta belgilangan: " + new Chiroyli("Namangan"));
    }
}

class Oddiy {
}

class Chiroyli {
    private final String nom;

    Chiroyli(String nom) {
        this.nom = nom;
    }

    @Override
    public String toString() {
        return "Chiroyli{nom='" + nom + "'}";
    }
}

public class Statik {
    public static void main(String[] args) {
        new Foydalanuvchi("Husanboy");
        new Foydalanuvchi("Malika");
        Foydalanuvchi oxirgi = new Foydalanuvchi("Nodira");

        System.out.println("Yaratilganlar soni: " + Foydalanuvchi.soni());
        System.out.println("Oxirgisi: " + oxirgi.ism());
        System.out.println("Doimiy: " + Foydalanuvchi.TIZIM);
    }
}

class Foydalanuvchi {
    static final String TIZIM = "Jurnal v1";
    private static int soni = 0;

    private final String ism;

    Foydalanuvchi(String ism) {
        this.ism = ism;
        soni++;
    }

    String ism() {
        return ism;
    }

    static int soni() {
        return soni;
    }
}

public class Hayot {
    public static void main(String[] args) {
        Hisoblagich a = new Hisoblagich();
        Hisoblagich b = a;              // yangi obyekt EMAS

        a.oshir();
        b.oshir();

        System.out.println("a: " + a.qiymat());
        System.out.println("b: " + b.qiymat());
        System.out.println("Bitta obyektmi: " + (a == b));

        Hisoblagich c = new Hisoblagich();
        System.out.println("c alohida: " + c.qiymat());
    }
}

class Hisoblagich {
    private int soni = 0;

    void oshir() {
        soni++;
    }

    int qiymat() {
        return soni;
    }
}