Strings

[Deepa Natarajan]

Q.1

public class Quest{
public static void main(String[] arg){
String s1 ="abc";
String s2 ="def";
String s3 =s1.concat(s2.toUpperCase());
system.out.println(s1+s2+s3);
}
}

Ans. abcdefabcDEF - I got this answer and it contradicts with the concept that String Objects are immutable.
How does it work?

Thanks,
Deepa

[ramu]

Hai Deepa,

String class is immutable. But StringBuffer class is mutable. String concatenation is immplemanted through
StringBuffer class and its append method.
Hope you understand

Deepa,

Strings are immutable. You can see that s1 or s2 remains unchanged.
The concat does not affect the string object on which it is called.
Also the toUppercase does not affect the string object.
These methods return a cha

Java language supports + operator which is same concat method in string.The + operator or concat method uses StringBuffer and append internally to change the String.So Strings are immutable is still true. The + operator/concat method is provided as this was available in C++,I guess.