Combining two similar methods in Java with predicate

user_5205189 0
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I have two similar methods in terms of the body, but with a different number of parameters and an extra condition inside. I know there is a way of merging them into a single method using a predicate, but I am not entirely sure how to implement it. Which is the best way to approach this?

public boolean checkIfAllCodesAreUnique(List<String> bsnCodes)
{
    List<Businesscode> codes = ConverterUtil.iterableToList(businessCodeService.findAll());
    if(codes != null && !codes.isEmpty() && bsnCodes != null && !bsnCodes.isEmpty())
        for (String code : bsnCodes)
            if (codes.stream().anyMatch(obj -> code.equals(obj.getCode())))
                return false;
    return true;
}

public boolean checkIfAllCodesAreUnique(List<String> bsnCodes, int idRole)
{
    List<Businesscode> codes = ConverterUtil.iterableToList(businessCodeService.findAll());
    if(codes != null && !codes.isEmpty() && bsnCodes != null && !bsnCodes.isEmpty())
        for (String code : bsnCodes)
            if (codes.stream().anyMatch(obj -> code.equals(obj.getCode()) && obj.getId() != idRole))
                return false;
    return true;
}
predicate lambda java
2 Answers
public boolean checkIfAllCodesAreUnique(List<String> bsnCodes) {
    return isAllCodesAreUnique(bsnCodes, businessCode -> true);
}

public boolean checkIfAllCodesAreUnique(List<String> bsnCodes, int idRole) {
    return isAllCodesAreUnique(bsnCodes, businessCode -> businessCode.getId() != idRole);
}

private boolean isAllCodesAreUnique(List<String> bsnCodes, Predicate<Businesscode> checkRole) {
    List<Businesscode> businessCodes = Optional.ofNullable(ConverterUtil
            .iterableToList(businessCodeService.findAll())).orElse(List.of());

    for (String bsnCode : Optional.ofNullable(bsnCodes).orElse(List.of())) {
        if (businessCodes.stream()
                         .filter(businessCode -> bsnCode.equals(businessCode.getCode()))
                         .anyMatch(checkRole))
            return false;
    }

    return true;
}
user_34613970

Basically predicate would not allow you anything specific in the sense of auto-determinable interface or whatever. Probably the best combination of the two would be:

public boolean checkIfAllCodesAreUnique(List<String> bsnCodes, Integer idRole)
{
    List<Businesscode> codes = ConverterUtil.iterableToList(businessCodeService.findAll());
    if(codes != null && !codes.isEmpty() && bsnCodes != null && !bsnCodes.isEmpty())
        for (String code : bsnCodes)
            if (codes.stream().anyMatch(obj -> code.equals(obj.getCode()) || (idRole != null && obj.getId() != idRole))
                return false;
    return true;
}

And then pass the second parameter as null whenever not available.

user_11080320
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