Difference Between StringBuffer(String str) and StringBuffer(CharSequence chars)
java, string
Solution
A `CharSequence` is an interface; it happens that `String` implements it.
This means that for instance, when you call `.charAt()` on a `String`, what is really called is the implementation of `String` for this method of `CharSequence`.
As you can see from the javadoc of `CharSequence`, not many classes in the JDK actually implement this interface.
As to why two constructors, `StringBuffer` dates back to Java 1.0 and `CharSequence` appears in 1.4 only; however, this is also the case that `StringBuilder` (which you should use, really, instead of `StringBuffer`) has two constructors (one with a `CharSequence` as an argument, another with a `String` as an argument), so there are probably optimizations implied when a `String` is passed as an argument. As to what such optimizations could be, well, it is a case of "Use The Source, Luke"(tm).
As an example of a `CharSequence` implementation which is not in the JDK, you can for example see one of my projects: largetext. Note that among other things, generating a `Matcher` from a `Pattern` uses a `CharSequence` and not a `String` as an argument; and since `String` implements `CharSequence`, well, passing a `String` as an argument works.
Problem
1.I am confused between these two,Do they have different functionality if so then How ? ``` StringBuffer(CharSequence chars) ``` and ``` StringBuffer(String str) ``` 2. What is basic Difference between String And CharSequence(Specially functionality) ?