String stuff

[meeta gaur]

class Example
{
	public static void main(String[] args) 
	{
		String s="I [surl='http://www.LearnNowJava.com' class='scratch' title='Hot Dog! LearnNowJava is keen on JavaRanch!']learn java[/surl].";
	
		String sub=s.subSequence(5,12);  
		System.out.println(sub);
		
	}
}

Example.java:12: error: incompatible types
String sub=s.subSequence(5,12);
^
required: String
found: CharSequence
1 error

String class implements CharSequence interface then why can't it hold returned object ?

[Henry Wong]

meeta gaur wrote:

class Example
{
	public static void main(String[] args) 
	{
		String s="I [surl='http://www.LearnNowJava.com' class='scratch' title='Hot Dog! LearnNowJava is keen on JavaRanch!']learn java[/surl].";
	
		String sub=s.subSequence(5,12);  
		System.out.println(sub);
		
	}
}

Example.java:12: error: incompatible types
String sub=s.subSequence(5,12);
^
required: String
found: CharSequence
1 error

String class implements CharSequence interface then why can't it hold returned object ?

All String objects are IS-A CharSequence, but not all CharSequence objects are IS-A String.

Henry

[Joanne Neal]

meeta gaur wrote:String class implements CharSequence interface then why can't it hold returned object ?

Because CharBuffer, Segment, StringBuffer and StringBuilder also implement CharSequence and so the compiler doesn't know that it will definitely be a String that is returned.
You can override this by putting an explicit cast in your code

String sub= (String ) s.subSequence(5,12); 

This says to the compiler - I know that the object returned from the method could be something other than a String, but I'm telling you it will be a String
Of course, if, at run time, something other than a String is returned, you will get a ClassCastException.

[meeta gaur]

Thanks to all.