Understanding Immutability and Strings

What is immutability in programming?

• Immutability allows objects to change their state freely.

• Immutability is the ability to create new objects from existing ones without any restrictions.

• Immutability is the property of an object that prevents its state from being modified after creation.

• Immutability refers to the process of deleting objects from memory after use.

How does immutability affect data structures?

• Immutability has no impact on the performance of data structures.

• Immutability makes data structures more flexible and easier to modify.

• Immutability leads to safer, more predictable data structures but can increase memory usage and performance overhead.

• Immutability allows for faster data access and lower memory usage.

Which of the following is an immutable type in Java?

• HashMap

• Integer

• ArrayList

• String

What is the primary purpose of the String class in Java?

• To store numerical values.

• To create user interfaces.

• To handle file input and output.

• To represent and manipulate sequences of characters.

How do you create a String object in Java?

• String objects are created by importing the String class from external libraries.

• You cannot create String objects in Java; they are automatically generated.

• You can create a String object in Java using 'new String("value")' or by using string literals like '"value"'.

• String objects can only be created using the StringBuilder class.

What is the difference between String and StringBuilder?

• StringBuilder is used for fixed-length strings; String is for variable-length.

• String is faster than StringBuilder for concatenation.

• String can be modified; StringBuilder cannot.

• String is immutable; StringBuilder is mutable.

When should you use StringBuilder over String?

• Use StringBuilder only for small strings to avoid overhead.

• StringBuilder is always faster than String, regardless of usage.

• Use StringBuilder for multiple string manipulations to improve performance.

• Use String for single string manipulations to save memory.

What method is used to append text to a StringBuilder?

• insert

• append

• concat

• add

How can you convert a StringBuilder back to a String?

• string result = stringBuilder.toString()

• string result = stringBuilder.convertToString();

• string result = stringBuilder.getString();

• string result = stringBuilder.asString();

What is the Object class in Java?

• The Object class is the root class of all classes in Java.

• The Object class is used to create user interfaces in Java.

• The Object class is a collection of utility methods for data manipulation in Java.

• The Object class is a special class for handling exceptions in Java.