As per my knowledge,
a mutable string can be changed, and an immutable string cannot be changed.
Here I want to change the value of String like this,
String str="Good";
str=str+" Morning";
and other way is,
StringBuffer str= new StringBuffer("Good");
str.append(" Morning");
In both the cases I am trying to alter the value of str. Can anyone tell me, what is difference in both case and give me clear picture of mutable and immutable objects.
10 Answers
Case 1:
String str = "Good";
str = str + " Morning";
In the above code you create 3 String Objects.
- "Good" it goes into the String Pool.
- " Morning" it goes into the String Pool as well.
- "Good Morning" created by concatenating "Good" and " Morning". This guy goes on the Heap.
Note: Strings are always immutable. There is no, such thing as a mutable String. str is just a reference which eventually points to "Good Morning". You are actually, not working on 1 object. you have 3 distinct String Objects.
