!!! HELP !!!! AM I writing wrong syntax???

Question

Is this a right syntax to add a character in a String in JAVA .....
SUPPOSE THE STRING BE---
String b;
And I want to add a blank space at the end..
So can I write....
String m=b+" ";
Is it correct,and is there any other way...
And what if I want to add a character in between the String.
Please help!!!
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