Java Interview Guide : 200+ Interview Questions and Answers - String, StringBuffer and StringBuilder

The video tutorial covers the concept of string immutability in Java, explaining that once a string object is created, its value cannot be changed. It discusses how strings are stored in memory, particularly in the string constant pool, and the implications of using string concatenation in loops, which can lead to performance issues. The tutorial compares String, StringBuffer, and StringBuilder, highlighting their differences in terms of mutability and thread safety. Practical exercises are suggested to explore these concepts further.

What does it mean for a string to be immutable in Java?

• The string can be changed only once.

• The string can be changed after creation.

• The string cannot be changed after creation.

• The string can be changed multiple times.

Where are string values stored in Java memory?

• In the stack memory

• In the file system

• In the CPU cache

• In the string constant pool within heap memory

Why is it not recommended to use string concatenation in loops?

• It creates a single object.

• It creates multiple new objects, impacting performance.

• It is not supported in Java.

• It modifies the original string.

Which class should be used for efficient string modifications in loops?

• StringBuffer

• Both StringBuffer and StringBuilder

• String

• StringBuilder

What is the main difference between StringBuffer and StringBuilder?

• StringBuffer is used for file operations, StringBuilder is not.

• StringBuffer is thread-safe, StringBuilder is not.

• StringBuffer is immutable, StringBuilder is mutable.

• StringBuffer is faster, StringBuilder is slower.

Which keyword is used to make StringBuffer thread-safe?

• transient

• volatile

• static

• synchronized

What is a common interview question regarding strings in Java?

• How to convert a string to an integer?

• How to create a string array?

• Difference between String and StringBuffer.

• How to reverse a string?