在Java中使用While循环对列表中的元素进行计数

Question

I am passing some parameters in the URL and then I add them in a list. My list has a limit of 5 elements. So if someone adds 6th element in the URL the list would simply ignore it. So I am trying to use a counter but the logic is not working as desired. I am using While loop to achieve this. So if list size is smaller than 5 set the agencyCds otherwise just return the list.

private List<IUiIntegrationDto> generateViewIntegrationReportData(ESignatureIntegrationConfig eSignConfig) throws Exception {
    int counter = 1;
    if(eSignConfig.getAdditionalAgencyCds() != null ) {

        List<String> combinedAgencyCds = new ArrayList<String>();

        for(String agencyCd : eSignConfig.getAgencyCd()) {
            combinedAgencyCds.add(agencyCd);
        }

        StringTokenizer token = new StringTokenizer(eSignConfig.getAdditionalAgencyCds().toString(), StringConstants.COMMA);
        while(token.hasMoreTokens()) {
            combinedAgencyCds.add(token.nextToken());
        }

        while(combinedAgencyCds.size() < 5) {
            counter = counter + 1;
            eSignConfig.setAgencyCd(combinedAgencyCds);
        }

    //  eSignConfig.setAgencyCd(combinedAgencyCds);
    } 
    List<IUiIntegrationDto> intgList = getUiIntegrationManager().retrieveUiIntegrationReportData(eSignConfig.getAgencyCd(), eSignConfig.getCreatedDays(),
            eSignConfig.getLob(), eSignConfig.getTransactionStatus(), eSignConfig.getAccounts(), eSignConfig.getSortKey(), eSignConfig.getSortOrder());

    return intgList;
}

I am not completely sure about this logic if it is correct or if there is nay better approach.

Thanks

Answer 1

Try this instead of the last while in your code:

if(combinedAgencyCds.size() <= 5) {
   eSignConfig.setAgencyCd(combinedAgencyCds); 
} else {
   eSignConfig.setAgencyCd(combinedAgencyCds.subList(0, 5));
}

The full combined list will then be used if it is less than 5 in size. Otherwise, only the first 5 elements are used.

Edit: Or even better:

eSignConfig.setAgencyCd(combinedAgencyCds.subList(0, Math.min(5, combinedAgencyCds.size())));

Answer 2

Ok so let's break down what your code is currently doing.

int counter = 1;

while(combinedAgencyCds.size() < 5) {
    counter = counter + 1;
    eSignConfig.setAgencyCd(combinedAgencyCds);
}

This snippet of code has a couple things wrong best I can tell. First, this loop has the possibility of running forever or not at all. Because combinedAgencyCds is never being manipulated, the size won't ever change and the logic being checked in the while loop never does anything. Second, there's a more efficient loop for doing this, assuming you don't need the counter variable outside of its usage in the while loop and that is using for loops.

Example syntax is as follows:

for (int i = 0; i < combinedAgencyCds.size(); i++) {
    if (i < 5) {        
        // Do your logic here.
    }
    else {
        break; // Or handle extra values however you want.
    }
}

Notice there is no need for the explicit declaration for a counter variable as "i" counts for you.

Now in your actual logic in the loop, I'm not sure what the setAgencyCd method does, but if it simply sets a list variable in the eSignConfig like it appears to, repeating it over and over isn't going to do anything. From what I can see in your code, you are setting a variable with the same value 5 times. If you need any more explanation just let me know and I will be happy to revise the answer.