Trooman Technologies Interview Questions and Answers

To convert list to arraylist, use ArrayList constructor. To convert arraylist to list, use List constructor.

• To convert list to arraylist, use ArrayList constructor and pass the list as parameter.

• To convert arraylist to list, use List constructor and pass the arraylist as parameter.

• Example: List list = Arrays.asList("one", "two", "three");

• ArrayList arrayList = new ArrayList<>(list);

• Example: ArrayList arrayList = new ArrayList<>(Arrays.asList("one", "two", "three"));

• List list =...read more

Functional interfaces are interfaces with only one abstract method. They are used for lambda expressions and method references.

• Functional interfaces are used for functional programming in Java.

• They are used for lambda expressions and method references.

• They have only one abstract method.

• Examples of functional interfaces are Runnable, Callable, and Comparator.

• Functional interfaces can be annotated with @FunctionalInterface to ensure they have only one abstract method.

Exceptions in Rest APIs are handled using try-catch blocks and appropriate error responses.

• Use try-catch blocks to catch exceptions that may occur during API execution.

• Handle different types of exceptions separately to provide specific error responses.

• Return appropriate HTTP status codes and error messages in the response.

• Log the exception details for debugging purposes.

• Consider using a global exception handler to centralize exception handling logic.

The highest limit of HashMap is Integer.MAX_VALUE, which is 2^31 - 1.

• The highest limit is determined by the maximum capacity of an array in Java, which is Integer.MAX_VALUE.

• The default initial capacity of a HashMap is 16, and it automatically increases its capacity as needed.

• If the number of elements exceeds the maximum capacity, an OutOfMemoryError will be thrown.

Streams in Java are a sequence of elements that can be processed in parallel or sequentially.

• Streams are used to perform operations on collections of data in a concise and functional way.

• They can be used to filter, map, reduce, and sort data.

• Streams can be processed in parallel to improve performance.

• Examples of stream methods include filter(), map(), reduce(), and sorted().

Run time polymorphism is method overriding while compile time polymorphism is method overloading.

• Compile time polymorphism is resolved at compile time while run time polymorphism is resolved at runtime.

• Method overloading is an example of compile time polymorphism while method overriding is an example of run time polymorphism.

• Compile time polymorphism is faster than run time polymorphism as it is resolved at compile time.

• Run time polymorphism is achieved through inheritance an...read more