我需要一个更好的方法来减少代码行，因为它有很多if语句，在条件中调用方法

Question

这是我的代码，我需要知道有没有办法减少程序中的行数。

因为if语句中涉及到方法调用，所以我不能使用枚举来替换它们。

public class AgreementQueryBuilder {

    @SuppressWarnings("unchecked")
    public static String searchQueryBuilder(FetchAgreementsModel agreementsModel,
            @SuppressWarnings("rawtypes") List obj) {

        StringBuilder selectQuery = new StringBuilder(
                "select *,e.id as agreementid from eglams_agreement e left outer join eglams_rentincrementtype  t on e.rent_increment_method=t.id where");

        // if statement to check the arguments and build the where criteria

        if (agreementsModel.getAgreementId() != null || agreementsModel.getAgreementNumber() != null
                || agreementsModel.getStatus() != null || agreementsModel.getTenantId() != null
                || (agreementsModel.getFromDate() != null && agreementsModel.getToDate() != null)
                || agreementsModel.getTenderNumber() != null || agreementsModel.getTinNumber() != null
                || agreementsModel.getTradeLicense_number() != null)
            return null;

        boolean isAllFieldsNull = true;

        if (agreementsModel.getAgreementId() != null) {
            if (isAllFieldsNull == true) {
                selectQuery.append(" e.id=?");
                isAllFieldsNull = false;
                obj.add(agreementsModel.getAgreementId());
            }
        }

        if (agreementsModel.getAgreementNumber() != null) {
            if (isAllFieldsNull == true) {
                selectQuery.append(" e.agreement_number=?");
                isAllFieldsNull = false;
            } else
                selectQuery.append(" and e.agreement_number=?");
            obj.add(agreementsModel.getAgreementNumber());
        }

        if (agreementsModel.getStatus() != null) {

            if (isAllFieldsNull == true) {
                selectQuery.append(" e.status=?");
                isAllFieldsNull = false;
            } else
                selectQuery.append(" and e.status=?");

            obj.add(agreementsModel.getStatus());
        }

        if (agreementsModel.getTenantId() != null) {
            if (isAllFieldsNull == true) {
                selectQuery.append(" e.tenant_id=?");
                isAllFieldsNull = false;
            } else
                selectQuery.append(" and e.tenant_id=?");

            obj.add(agreementsModel.getTenantId());
        }

        if (agreementsModel.getTenderNumber() != null) {
            if (isAllFieldsNull == true) {
                selectQuery.append(" e.tender_number=?");
                isAllFieldsNull = false;
            } else
                selectQuery.append(" and e.tender_number=?");
            obj.add(agreementsModel.getTenderNumber());
        }
        if (agreementsModel.getTinNumber() != null) {
            if (isAllFieldsNull == true) {
                selectQuery.append(" e.tin_number=?");
                isAllFieldsNull = false;
            } else
                selectQuery.append(" and e.tin_number=?");
            obj.add(agreementsModel.getTinNumber());
        }

        if (agreementsModel.getTradeLicense_number() != null) {
            if (isAllFieldsNull == true) {
                selectQuery.append(" e.TradeLicense_number=?");
                isAllFieldsNull = false;
            } else
                selectQuery.append(" and e.TradeLicense_number=?");
            obj.add(agreementsModel.getTradeLicense_number());
        }

        if (agreementsModel.getFromDate() != null) {
            if (agreementsModel.getToDate() != null) {
                if (isAllFieldsNull == true) {
                    selectQuery.append(" t.FromDate=?");
                    isAllFieldsNull = false;
                } else
                    selectQuery.append(" and t.FromDate=?");

                obj.add(agreementsModel.getFromDate());
                selectQuery.append(" and t.ToDate=?");
                obj.add(agreementsModel.getToDate());
            }
        }
        System.err.println(selectQuery);
        return selectQuery.toString();
    }
}

Answer 1

查看您的代码：

if (agreementsModel.getAgreementId() != null ||  ... )
    return null;

因此，我们知道，如果getAgreementId（）！=null，该方法将返回null，并且不会进一步执行。但在那之后你会写：

if (agreementsModel.getAgreementId() != null) {
        selectQuery.append(" e.id=?");
        isAllFieldsNull = false;
        obj.add(agreementsModel.getAgreementId());
    }
}

我们知道不能输入整个块，因为如果getAgreementId（）！=null为true，方法就会返回。

if (agreementsModel.getAgreementId() != null || agreementsModel.getAgreementNumber() != null
            || agreementsModel.getStatus() != null || agreementsModel.getTenantId() != null
            || (agreementsModel.getFromDate() != null && agreementsModel.getToDate() != null)
            || agreementsModel.getTenderNumber() != null || agreementsModel.getTinNumber() != null
            || agreementsModel.getTradeLicense_number() != null)
        return null;