Handle Null Value

Scenario 1

We are working with the method chain:

response.getSuccess().getAccounts().get(0).getId()

This is vulnerable to a NullPointerException if any part of the chain is null or the list is empty.

Goal: Return the result of getId() if all parts are non-null. If any part is null or the list is empty, return "" (empty string).

1. Classic Nested Null Checks

This is the most straightforward and safe method.

if (response != null &&
    response.getSuccess() != null &&
    response.getSuccess().getAccounts() != null &&
    !response.getSuccess().getAccounts().isEmpty() &&
    response.getSuccess().getAccounts().get(0) != null &&
    response.getSuccess().getAccounts().get(0).getId() != null) {
    
    return response.getSuccess().getAccounts().get(0).getId();
} else {
    return "";
}

• Safe and explicit

• Verbose but readable

• Recommended in core business logic when full control is needed

2. Using Optional (Java 8+)

This method is more concise and uses functional style.

return Optional.ofNullable(response)
        .map(r -> r.getSuccess())
        .map(s -> s.getAccounts())
        .filter(accounts -> !accounts.isEmpty())
        .map(accounts -> accounts.get(0))
        .map(account -> account.getId())
        .orElse("");

return Optional.ofNullable(response)
        .map(Response::getSuccess)
        .map(Success::getAccounts)
        .flatMap(accounts -> accounts.stream().findFirst())
        .map(Account::getId)
        .orElse("");

• Null-safe

• Cleaner

• Useful for deep object trees

• May not be as readable to developers unfamiliar with functional chains

3. Custom Helper Method

Encapsulate the null-safe logic inside a method:

public String getFirstAccountId(Response response) {
    if (response == null) return "";
    var success = response.getSuccess();
    if (success == null) return "";
    var accounts = success.getAccounts();
    if (accounts == null || accounts.isEmpty()) return "";
    var firstAccount = accounts.get(0);
    if (firstAccount == null || firstAccount.getId() == null) return "";
    return firstAccount.getId();
}

• Centralized

• Reusable

• Easy to unit test

• Keeps business code clean

4. Using Try-Catch Block (Not Recommended)

try {
    return response.getSuccess().getAccounts().get(0).getId();
} catch (NullPointerException | IndexOutOfBoundsException e) {
    return "";
}

• Works, but poor style

• Exceptions should not be used for control flow

• Hides logic issues and makes debugging harder

• Slower at runtime due to exception overhead