if (Boolean.TRUE.equals(bool)) { // check first key String firstKey = keys.iterator().next(); if (firstKey == "public") { keys.stream().forEach(key -> { // ... some logic log.warn("Using key " + key); }); } } public BookStoreController(BooksRepository repo, Boolean bool, List<String> keys) { this.repo = repo; if (Boolean.TRUE.equals(bool)) { // check first key String firstKey = (String) ((ArrayList) keys).get(0); if (firstKey == "public") { keys.stream().forEach(key -> { // ... some logic log.warn("Using key " + key); }); } } }

The provided code has several issues related to string comparison and type casting:

1. String comparison using ==

In Java, strings should be compared using the .equals() method, not the == operator, because == compares references, not content. In the code:

if (firstKey == "public") {

should be replaced with

if ("public".equals(firstKey)) {

2. Casting keys to ArrayList

Casting keys to ArrayList in the constructor can lead to a ClassCastException if a different list implementation is passed. It's better to use the List interface and methods that do not depend on the specific implementation:

String firstKey = keys.get(0);

3. General advice

• Use Boolean.TRUE.equals(bool) for safe comparison with Boolean objects to avoid NullPointerException.
• Use forEach or a for loop for iterating over lists.

The corrected code snippet:

if (Boolean.TRUE.equals(bool)) {
    String firstKey = keys.get(0);
    if ("public".equals(firstKey)) {
        keys.forEach(key -> {
            // ... some logic
            log.warn("Using key " + key);
        });
    }
}

This ensures proper string comparison and safe collection handling.