Java Concepts Assessment

Front

What is an immutable class in Java?

Back

An immutable class in Java is a class whose instances cannot be changed after creation.

Front

How do you create an immutable class in Java?

Back

Declare the class as final, make fields private and final, provide a constructor, and omit setter methods.

Front

Which of the following classes is immutable: String, StringBuilder, StringBuffer?

Back

String

Front

What method would you use to find the length of a String in Java?

Back

Use the length() method of the String class.

Front

How do you concatenate two Strings in Java?

Back

Use '+' operator or String.concat() method.

Front

What is the primary difference between StringBuilder and StringBuffer?

Back

StringBuilder is faster and not thread-safe; StringBuffer is thread-safe but slower.

Front

Which class is synchronized: StringBuilder or StringBuffer?

Back

StringBuffer

Front

What is the purpose of the StringBuilder class?

Back

The purpose of the StringBuilder class is to efficiently build and manipulate strings.

Front

How do you convert a StringBuilder to a String?

Back

stringBuilder.toString()

Front

What are Java Records introduced in Java 14?

Back

Java Records are a feature in Java 14 that simplify the creation of data-carrying classes with immutable properties.