Java 8 Lambda空值检查用法

Question

I have a scenario where I am checking multiple attributes inside a class for null check.If its not null , I am calling a method which will create me a new object and I need to capture this instance against a reference.I am succesasfully able to do null check using maps but unable to write code which will help me in capturing the return object after invocation.Can someone please help ?

    private WorkflowPreference buildWfPrefDetails(CcarReportPreferenceConfig ccarReportPreferenceConfig) {
    WorkflowPreference workflowPreference = new WorkflowPreference();
    List<PayloadEntry> payLoadEntries = new ArrayList<PayloadEntry>();
    Optional.of(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getRwpRole)
        .map(RwpRole::getRoleName)
        .ifPresent(s -> workflowPreference.setKey(s));
    Optional.of(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getSequenceNumber)
        .ifPresent(s -> buildPayLoadEntry("SEQ_NUM", s));
    Optional.of(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getSlaType)
        .ifPresent(s -> buildPayLoadEntry("SLA_TYPE", s));
    Optional.of(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getSlaValue)
        .ifPresent(s -> buildPayLoadEntry("SLA_VALUE", s.toString()));
    Optional.of(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getRejectSequence)
        .ifPresent(s -> buildPayLoadEntry("REJECT_SEQUENCE", s));
    Optional.of(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getRaiseQueryNotification)
        .ifPresent(s -> buildPayLoadEntry("RAISE_QUERY_NOTIFICATION", s));
    workflowPreference.getValue().addAll(payLoadEntries);
    return workflowPreference;
}

private PayloadEntry buildPayLoadEntry(String key, String value) {
    PayloadEntry payloadEntry = new PayloadEntry();
    payloadEntry.setKey(key);
    payloadEntry.setValue(value);
    return payloadEntry;
}

Expected Now :

payloadEntries list should capture the returned object after each buildPayloadEntry call.I want something like below to be implemented along with lambda null checks

payLoadEntries.add(buildPayLoadEntry("SEQ_NUM", ccarReportPreferenceConfig.getSequenceNumber()));
payLoadEntries.add(buildPayLoadEntry("SLA_TYPE", ccarReportPreferenceConfig.getSlaValue().toString()));

Updated Answer as per below suggestions

Optional.ofNullable(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getRwpRole)
        .map(RwpRole::getRoleName)
        .ifPresent(s -> workflowPreference.setKey(s));
    Optional.ofNullable(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getSequenceNumber)
        .ifPresent(s -> payLoadEntries.add(buildPayLoadEntry("SEQ_NUM", s)));
    Optional.ofNullable(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getSlaType)
        .ifPresent(s -> payLoadEntries.add(buildPayLoadEntry("SLA_TYPE", s)));
    Optional.ofNullable(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getSlaValue)
        .ifPresent(s -> payLoadEntries.add(buildPayLoadEntry("SLA_VALUE", s.toString())));
    Optional.ofNullable(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getRejectSequence)
        .ifPresent(s -> payLoadEntries.add(buildPayLoadEntry("REJECT_SEQUENCE", s)));
    Optional.ofNullable(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getRaiseQueryNotification)
        .ifPresent(s -> payLoadEntries.add(buildPayLoadEntry("RAISE_QUERY_NOTIFICATION", s)));
    workflowPreference.getValue().addAll(payLoadEntries);

Answer 1

If I understand correctly, you just need to transform (for example):

Optional.of(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getSequenceNumber)
        .ifPresent(s -> buildPayLoadEntry("SEQ_NUM", s));

to

Optional.of(ccarReportPreferenceConfig)
        .map(CcarReportPreferenceConfig::getSequenceNumber)
        .ifPresent(s -> payLoadEntries.add(buildPayLoadEntry("SEQ_NUM", s)));