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In Java, a String
object is immutable, meaning that once it is created, its contents cannot be changed. This means that any changes to a String
object result in the creation of a new String
object.
This behavior of String
objects being immutable is by design, and has several benefits. It makes String
objects thread-safe, which means that multiple threads can access a String
object without the risk of unexpected changes. It also allows for better memory management, as immutable objects can be cached and reused without having to worry about their contents changing.
Let’s take a look at an example to see how String
immutability works in practice:
javascript
String s1 = "Hello";
String s2 = s1;
s1 = s1 + " World";
In the above code, we create two String
objects, s1
and s2
, both containing the string “Hello”. We then modify s1
by concatenating the string ” World” to it. However, this does not change the value of s2
, which still contains the original string “Hello”. Instead, a new String
object is created with the value “Hello World”, and s1
now references this new object.
This immutability of String
objects means that any operations that modify the contents of a String
object, such as concatenation or substring operations, will result in the creation of a new String
object. This can have performance implications if these operations are performed frequently on large String
objects.
In conclusion, understanding the immutability of String
objects in Java are important for writing efficient and safe code. It is important to keep in mind that any modifications to a String
object result in the creation of a new object, and to use the appropriate data structures and algorithms to optimize performance when working with String
objects.