perpustakaan apache-commons-lang

Metode complicated equals().

Kanggo gampang ngleksanakake cara equals , sampeyan bisa nggunakake kelas EqualsBuilder . Ing ngisor iki sawetara conto kanggo nuduhake cara kerjane.

Nyetel kolom khusus kanggo mbandhingake:

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();
   }
}

Uga, kelas iki bisa mbandhingake obyek liwat refleksi:

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

Metode hashCode() rumit

Kanggo ngleksanakake metode hashCode , sampeyan kudu nggunakake kelas HashCodeBuilder .

Pilihan lapangan:

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

Nggunakake refleksi kanggo mbangun kode hash:

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

We use reflection and ignore certain fields:
@Override
public int hashCode() {
   return HashCodeBuilder.reflectionHashCode(this, "name");
}

Metode toString() rumit

Kanthi cara sing padha, sampeyan bisa uga ngetrapake metode toString () . Maneh, kita nggunakake kelas ToStringBuilder .

Kothak kasebut disetel kaya ing rong kasus sadurunge:

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

Tuladha asil:

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

Sampeyan uga bisa nemtokake jeneng lapangan kanthi eksplisit:

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

Tuladha asil:

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

Sampeyan bisa ngganti gaya teks nggunakake setelan:

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

Tuladha asil:

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

Ana sawetara gaya kaya JSON, ora ana Classname, cendhak lan liya-liyane.

Nggunakake refleksi:

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

Nggunakake refleksi lan nemtokake gaya tartamtu:

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