Convert Kotlin Collections (.find, .map) into Java

user_7581159 0
Viewed 174

I need to convert the following kotlin code to java:

private fun processPurchases(allPurchases: List<Purchase>, purchasedProductsFetched: Boolean) {

    val validPurchases = allPurchases.filter {
        isPurchaseSignatureValid(it)
    }.map { purchase ->
        val skuDetails = fetchedSkuInfosList.find { it.skuId == purchase.sku }!!.skuDetails
        PurchaseInfo(
            generateSkuInfo(skuDetails),
            purchase
        )
    }
}

I am stuck after .map part and can't figure out what's going on...

private void processPurchases(List<Purchase> allPurchases, boolean purchasedProductsFetched) {
    
    List<Purchase> validPurchases = new ArrayList<>();

    for (Purchase purchase : allPurchases) {
        if (isPurchaseSignatureValid(purchase)) {
            validPurchases.add(purchase);
        }
    }
}

Can someone explain what to do next?

kotlin java
3 Answers

You could also take advantage Java streams and take a more functional like approach:

void process(List<Purchase> allPurchases, Boolean purchasedProductsFetched) {
    List<PurchaseInfo> validPurchases = allPurchases
            .stream()
            .filter(this::isPurchaseSignatureValid)
            .map(purchase ->
                    new PurchaseInfo(
                            fetchedSkuInfosList
                                    .stream()
                                    .filter(it -> it.getSkuId().equals(purchase.getSku()))
                                    .findFirst()
                                    .get()//the get here is as unsafe as the !! in kotlin
                                    .getSkuDetails(),
                            purchase
                    )
            ).collect(Collectors.toList());
}

Note, this replicates the mistakes from the given kotlin code. The null safety issue with !!, the unused purchasedProductsFetched property, and the unused validPurchases.

user_99408200

Firstly, validPurchases list needs PurchaseInfo type instead od Purchase. So you need to write smth like that:

validPurchases.add(PurchaseInfo(generateSkuInfo(skuDetails),purchase));
user_116369290

@Konrad Pękala answer helped me to understand in which direction to look.

private void processPurchases(List<Purchase> allPurchases, boolean purchasedProductsFetched) {
    if (!allPurchases.isEmpty()) {

        List<PurchaseInfo> validPurchases = new ArrayList<>();

        for (Purchase purchase : allPurchases) {
            if (isPurchaseSignatureValid(purchase)) {
                for (SkuInfo skuInfo : fetchedSkuInfoList) {
                    if (skuInfo.getSkuId().equals(purchase.getSku())) {
                        SkuDetails skuDetails = skuInfo.getSkuDetails();

                        PurchaseInfo purchaseInfo = new PurchaseInfo(generateSkuInfo(skuDetails), purchase);
                        validPurchases.add(purchaseInfo);
                    }
                }
            }
        }


    }
}
user_75811590
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