toUpperCase in Java does not work

I have a string:

String c = "IceCream";

If I use toUpperCase() function then it returns the same string, but I want to get "ICECREAM".

Where is the problem?

Solution 1:

The code

String c = "IceCream";
String upper = c.toUpperCase();
System.out.println(upper);

correctly prints "ICECREAM". However, the original string c isn't changed. Strings in Java are immutable so all operations on the string return a new copy.

Solution 2:

Are you expecting the original variable, c, to have been changed by toUpperCase()? Strings are immutable; methods such as .toUpperCase() return new strings, leaving the original un-modified:

String c = "IceCream";
String d = c.toUpperCase();
System.out.println(c); // prints IceCream
System.out.println(d); // prints ICECREAM

Solution 3:

The object can't be changed, because String is immutable. However, you can have the reference point to a new instance, which is all uppercase:

String c = "IceCream";
c = c.toUpperCase();