Here is the solution. Please comment if you have beter approach

public static void main(String[] args) { Scanner in = new Scanner(System.in); int nooftestcases = in.nextInt();

    for (int i = 1; i <= nooftestcases; i++) {
        String test = in.next();
        int count=0;
        for (int j = 0; j < test.length()-1; j++) {
            if(test.charAt(j)==test.charAt(j+1))
                count++;
          } 
        System.out.println(count);
    }
}