apache-commons-lang kutubxonasi

Murakkab equals() metodi

Metodni osonlik bilan amalga oshirish uchun equals EqualsBuilder klassidan foydalanish mumkin. Mana bir nechta misollar, qanday ishlashini ko'rsatadi.

Ma'lum bir maydonlarni taqqoslash uchun berish:

public class User {
   private String name;
   private String email;

   @Override
   public boolean equals(Object o) {
       if (this == o) return true;

       if (!(o instanceof User user)) return false;

       return new EqualsBuilder().append(name, user.name).append(email, user.email).isEquals();
   }
}

Bu klass reflection orqali ob'ektlarni taqqoslashi ham mumkin:

@Override
public boolean equals(Object obj) {
   return EqualsBuilder.reflectionEquals(this, obj);
}

Murakkab hashCode() metodi

Metodni amalga oshirish uchun hashCode HashCodeBuilder klassidan foydalanish kerak.

Maydonlarni tanlash:

@Override
public int hashCode() {
   return new HashCodeBuilder(17, 37)
           .append(name)
           .append(email)
           .toHashCode();
}

reflection orqali hash-code qurish:

@Override
public int hashCode() {
   return HashCodeBuilder.reflectionHashCode(this);
}

reflectiondan foydalanamiz va ma'lum maydonlarni e'tiborsiz qoldiramiz:
@Override
public int hashCode() {
   return HashCodeBuilder.reflectionHashCode(this, "name");
}

Murakkab toString() metodi

Xuddi shu sxemaga muvofiq, metodi toString() ham amalga oshirilishi mumkin. Yana ToStringBuilder klasidan foydalanamiz.

Maydonlar oldingi ikki holatda ham berilmoqda:

@Override
public String toString() {
   return new ToStringBuilder(this)
           .append(name)
           .append(email)
           .toString();
}

Natija namunasi:

org.example.User@4b67cf4d[name=John,email=email@email.com]

Maydon nomlarini aniq ko'rsatishimiz mumkin:

@Override
public String toString() {
   return new ToStringBuilder(this)
           .append("nameUser", name)
           .append("emailUser", email)
           .toString();
}

Natija namunasi:

org.example.User@4b67cf4d[nameUser=John,emailUser=email@email.com]

Matn uslubini sozlamalar orqali o'zgartirishimiz mumkin:

@Override
public String toString() {
   return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
           .append(name)
           .append(email)
           .toString();
}

Natija namunasi:

User[John,emailUser=email@email.com]

Bir nechta uslublar mavjud, masalan JSON, no Classname, short va boshqalar.

reflectiondan foydalanish:

@Override
public String toString() {
   return ToStringBuilder.reflectionToString(this);
}

reflectiondan foydalanish va ma'lum bir uslubni belgilash:

@Override
public String toString() {
   return ToStringBuilder.reflectionToString(this, ToStringStyle.SHORT_PREFIX_STYLE);
}