如何在运行UBL XML读取时使用很少的ifs检查null

您可以编写一个函数来执行 null 检查并重用它：

import java.util.function.Consumer;
import java.util.function.Function;

interface Despatch {

    SupplierParty getDespatchSupplierParty();
}
interface SupplierParty {

    Party getParty();
}
interface Party {
    Contact getContact();
}
interface Contact {
    Telephone getTelephone();

    Telefax getTelefax();

    EMail getElectronicMail();

    Name getName();
}
interface Telephone {
    String getValue();
}
interface Telefax {

    String getValue();
}
interface EMail {
    String getValue();
}
interface Name {
    String getValue();

}
interface TFDESP000_ARCH {

    void setDcpPartyContactTelephone(String value);

    void setDcpPartyContactTelefax(String value);

    void setDspPartyContactElectronicMail(String value);

    void setDspContactName(String value);
}
public class App {

    public static void main(String[] args) {
        Despatch despt = ...;
        TFDESP000_ARCH tfdesp000_arch = ...;

        // shorter version
        Contact contact = despt.getDespatchSupplierParty().getParty().getContact();
        setContactField(contact, Contact::getTelephone, Telephone::getValue, tfdesp000_arch::setDcpPartyContactTelephone);
        setContactField(contact, Contact::getTelefax, Telefax::getValue, tfdesp000_arch::setDcpPartyContactTelefax);
        setContactField(contact, Contact::getElectronicMail, EMail::getValue, tfdesp000_arch::setDspPartyContactElectronicMail);
        setContactField(contact, Contact::getName, Name::getValue, tfdesp000_arch::setDspContactName);
    }
    
    private static <T> void setContactField(Contact contact, Function<Contact, T> getField, Function<T,String> getValue, Consumer<String> setter) {
        if (contact != null) {
            T field = getField.apply(contact);
            if (field != null) {
                setter.accept(getValue.apply(field));
            }
        }
    }
}

某些类型在这里可能是错误的，因为您没有给出方法的签名。例如，如果 doesn't always return ，则可以向该方法添加另一个类型参数：getValueStringsetContactField

private static <T,U> void setContactField(Contact contact, Function<Contact, T> getField, Function<T,U> getValue, Consumer<U> setter)

在 set 方法的逻辑中，在此处添加 null 检查。

• setDcpPartyContactTelephone（...）
• setDcpPartyContactTelefax（...）
• setDspPartyContactElectronicMail（...）
• setDspContactName（..）

示例代码：

public void setDcpPartyContactTelephone(Telephone telephone) {
    if(telephone != null) {
        String value = telephone.getValue();
        //Continue normal operations
    }
}

将联系人声明为变量：

Contact contact = despt.getDespatchSupplierParty().getParty().getContact();

您的完整代码如下所示：

Contact contact = despt.getDespatchSupplierParty().getParty().getContact();
if(contact != null) {
    tfdesp000_arch.setDcpPartyContactTelephone(contact.getTelephone());
    tfdesp000_arch.setDcpPartyContactTelefax(contact.getTelefax());
    tfdesp000_arch.setDspPartyContactElectronicMail(contact.getElectronicMail());
    tfdesp000_arch.setDspContactName(contact.getName());
}