Объедините список из 2 различных объектов списка, поместите содержимое объектов в третий список объектов с полями первых 2 в Java

Как насчет простого метода, управляемого доменом, с помощью аксессуаров и мутаторов (getters и seters)?

MemberData memberData = new MemberData();
memberData.copyMember(/* Member instance */); //Inside get from member and set at memberData.
memberData.copyEligibility(/* Eligibility instance*/); //Inside get from eligibility and set at memberData.

Вы можете запускать некоторые циклы верхнего уровня, чтобы иметь соответствующие данные о приемлемости для члена, и создать экземпляр MemberData.

**** РЕДАКТИРОВАТЬ ****

См. Примеры объектов и образец кода...

public class Member implements Serializable {
public MemberPK getId() {
    return id;
}

public void setId(MemberPK id) {
    this.id = id;
}

public char getBusinessUnit() {
    return businessUnit;
}

public void setBusinessUnit(char businessUnit) {
    this.businessUnit = businessUnit;
}

public char getDeletedInd() {
    return deletedInd;
}

public void setDeletedInd(char deletedInd) {
    this.deletedInd = deletedInd;
}

public String getFirstname() {
    return firstname;
}

public void setFirstname(String firstname) {
    this.firstname = firstname;
}

private static final long serialVersionUID = 1L;

private MemberPK id;

private char businessUnit;

private char deletedInd;

private String firstname;


}

public class Eligibility implements Serializable {
private static final long serialVersionUID = 1L;

private MemberSpanPK id;

private String affNbr;

private Character businessUnit;

private char carrier;

private String deleteInd;

public MemberSpanPK getId() {
    return id;
}

public void setId(MemberSpanPK id) {
    this.id = id;
}

public String getAffNbr() {
    return affNbr;
}

public void setAffNbr(String affNbr) {
    this.affNbr = affNbr;
}

public Character getBusinessUnit() {
    return businessUnit;
}

public void setBusinessUnit(Character businessUnit) {
    this.businessUnit = businessUnit;
}

public char getCarrier() {
    return carrier;
}

public void setCarrier(char carrier) {
    this.carrier = carrier;
}

public String getDeleteInd() {
    return deleteInd;
}

public void setDeleteInd(String deleteInd) {
    this.deleteInd = deleteInd;
} 
}

public class MemberPK {
private String memberNbr;

public String getMemberNbr() {
    return memberNbr;
}

public void setMemberNbr(String memberNbr) {
    this.memberNbr = memberNbr;
}
}

public class MemberSpanPK {
private String memberNbr;

public String getMemberNbr() {
    return memberNbr;
}

public void setMemberNbr(String memberNbr) {
    this.memberNbr = memberNbr;
}
}

public class EligibilityVO {
//Eligibility 
private String memberpcp;
private String bu;
private String carrier;
private String deletedInd;
public String getMemberpcp() {
    return memberpcp;
}
public void setMemberpcp(String memberpcp) {
    this.memberpcp = memberpcp;
}
public String getBu() {
    return bu;
}
public void setBu(String bu) {
    this.bu = bu;
}
public String getCarrier() {
    return carrier;
}
public void setCarrier(String carrier) {
    this.carrier = carrier;
}
public String getDeletedInd() {
    return deletedInd;
}
public void setDeletedInd(String deletedInd) {
    this.deletedInd = deletedInd;
}
}

public class MemberData {
 // Members
private String membernbr;
private String medicaidNbr;
private String namefirst;
private String namelast;
private List<EligibilityVO> eligibilities;
public List<EligibilityVO> getEligibilities() {
    return eligibilities;
}
public void setEligibilities(List<EligibilityVO> eligibilities) {
    this.eligibilities = eligibilities;
}
public void addEligibilities(EligibilityVO eligibility) {
    if(null == this.eligibilities) {
        this.eligibilities = new ArrayList<EligibilityVO>();
    }
    this.eligibilities.add(eligibility);
}
public String getMembernbr() {
    return membernbr;
}
public void setMembernbr(String membernbr) {
    this.membernbr = membernbr;
}
public String getMedicaidNbr() {
    return medicaidNbr;
}
public void setMedicaidNbr(String medicaidNbr) {
    this.medicaidNbr = medicaidNbr;
}
public String getNamefirst() {
    return namefirst;
}
public void setNamefirst(String namefirst) {
    this.namefirst = namefirst;
}
public String getNamelast() {
    return namelast;
}
public void setNamelast(String namelast) {
    this.namelast = namelast;
}    

}

И образец класса для объединения данных...

public class MergeData {

public static void main(String[] args) {

  List<Member> members = new ArrayList<Member>();//Your service level member list here
  List<Eligibility> eligibilities = new ArrayList<Eligibility>();//Your service level eligibility list here
  List<MemberData> memberDatas = new ArrayList<MemberData>();
  for (Member member : members) {
    MemberData memberData = new MemberData(); 
    for (Eligibility eligibility : eligibilities) {
        if(member.getId().getMemberNbr() == eligibility.getId().getMemberNbr()) {
            EligibilityVO eliVo = new EligibilityVO();
            eliVo.setBu(eligibility.getAffNbr());
            //set others
            memberData.addEligibilities(eliVo);
        }
    }
    memberData.setNamefirst(member.getFirstname());
    //Set others
  }
  }
  }

Надеюсь это поможет.