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I know we can convert a string builder to string using toString() and new String(stringbuilder) functions and constructor.. But I want to know the reason why this statement raises an error as "StringBuilder cannot be converted to String"
Java
String s = (String) StringBuilder;


What I have tried:

Convert stringbuilder to string using string literal
Posted
Updated 14-Feb-18 1:07am
v3

Because a StringBuilder is a different class, and cannot be directly used as a String. You must use the toString() method, as described in the documentation.
 
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v2
There is no such thing as a StringBuilder to String conversion.
StringBuilder class provides you with a toString method which allows you to get the string which is actually stored in the internal buffer of the StringBuilder object.
You have to use
Java
String s = sb.ToString();
, sb being a variable of the StringBuilder class.
Java
// Bad code!
String s = (String)StringBuilder;

is not correct on at least two levels:

  • You cannot cast a StringBuilder variable to a string directly.
  • StringBuilder is a class, not a variable. You cannot cast a class to anything, you only cast variables.
 
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Well, I guess in case of type casting you'll have to take check for the "IS-A" test which would fail in this case as StringBuilder is NOT a String. In case of conversion you explicitly have to use the "toString()"(note that 't' isn't capital).
 
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