String vs String buffer java interview Question part-9

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In Java, both String and StringBuffer are used to manipulate strings, but they have some differences in terms of mutability, performance, and usage.

String:

Immutable: Once a String object is created, it cannot be changed. Any operation that appears to modify a String actually creates a new String object.
Thread-safe: Since String objects are immutable, they are inherently thread-safe and can be safely shared among multiple threads.
Concatenation: When concatenating multiple strings using the + operator, it creates a new String object each time, which can be inefficient if done repeatedly in a loop.
Usage: String is suitable when you have a fixed value or a constant string that doesn't require frequent modifications.
StringBuffer:

Mutable: StringBuffer objects are mutable, meaning you can modify their contents without creating a new object. This can be useful when you need to perform multiple modifications to a string.

Not thread-safe by default: StringBuffer methods are not synchronized by default. However, it provides synchronized methods (append, insert, etc.) that can be used for thread-safe operations.
Efficient concatenation: StringBuffer provides a append method to efficiently concatenate strings. It modifies the existing StringBuffer object instead of creating new objects.
Usage: StringBuffer is recommended when you need to perform multiple modifications to a string, such as concatenation in a loop, where efficiency is a concern.
In Java 5 and later versions, StringBuilder is introduced as an alternative to StringBuffer. StringBuilder has similar characteristics to StringBuffer but is not thread-safe. It is typically preferred in single-threaded environments where synchronization is not required.

In summary, if you need an immutable and thread-safe string, use String. If you need a mutable string for efficient modifications, especially in a multi-threaded environment, use StringBuffer or StringBuilder.

string s1=new string("Bikash");
s.concat("software");
sop(s);
Output=Bikash

stringBuffer s1=new stringBuffer("Bikash");
s1.append("software");
sop(s);

Output:-Bikash software