java 13 interview questions and answers

new ArrayList(Arrays.asList(myArray)) To convert a String array to an ArrayList in Core Java, you can use the Arrays.asList() method to convert the array to a List and then create an ArrayList from that List. Here’s an example: java import java.util.ArrayList; import java.util.Arrays; import java.util.List;public class StringArrayToArrayList { public static void main(String[] args) { // Example String … Read more

The methods to override are equals() and hashCode(). For the HashMap class in Java, the key class should override the hashCode() and equals() methods. These methods are crucial for proper functioning of the HashMap as they determine how keys are stored and retrieved in the underlying data structure. Here’s a brief explanation of each method: … Read more

Collections.synchronizedMap(new HashMap()); Collections.synchronizedList(List<T> list) In Java, if you want to make a Map or List thread-safe or synchronized, you can use the Collections.synchronizedMap and Collections.synchronizedList methods, respectively. These methods return synchronized versions of the provided Map or List. Here’s how you can use them: For a Map: java Map<String, Object> synchronizedMap = Collections.synchronizedMap(new HashMap<>()); For … Read more

Iterator : Iterator takes the place of Enumeration in the Java collections framework. One can traverse throughr the the collection with the help of iterator in forward direction only and Iterators allow the caller to remove elements from the underlying collection during the iteration with well-defined semantics ListIterator: An iterator for lists that allows one to traverse … Read more

HashSet : HashSet does not allow duplicate values. It provides add method rather put method. You also use its contain method to check whether the object is already available in HashSet. HashSet can be used where you want to maintain a unique list. HashMap : It allows null for both key and value. It is unsynchronized. So come … Read more