Question

What would be a concise regular regular expression to remove everything from a string that is not an alphabet

        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
    int T=0; 
    try{
        T= Integer.parseInt(br.readLine());

        while(T>0)
                String input=br.readLine();
                **String res= input.replaceAll("^[a-zA-Z]"," " );**
                System.out.println(res);

Also tried

      input.replaceAll("[^a-zA-Z]]"," " )

Neither of them is replacing anything from the input string.The input string remains just as it was

Edit:

         input.replaceAll("[^a-zA-Z]"," " )  //works well
         input.replaceAll("^[a-zA-Z]"," " )  //replaces first char of string

Answer 1

You need:

input = input.replaceAll("[^a-zA-Z]"," " );
^^^^^^^                          ^ ^

You need to make the input reference point to the String object returned by the replaceAll method to get the changed string as Strings are immutable.

The range A-z is not something you want. You need A-Z.

Also you have an extra ] in your pattern.

See it