Find duplicate characters in a String and count the number of occurances

public class ReadChars {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        String text = scanner.nextLine();

        for (int i = 0; i < text.length(); ) {
            int temp = 0;

            for (int j = 0; j < text.length(); j++) {
                char a = text.charAt(i);

                if (String.valueOf(a).toUpperCase().equals(String.valueOf(text.charAt(j)).toUpperCase())) {
                    temp++;
                }
            }

            System.out.println(text.charAt(i) + " " + String.valueOf(temp));
            temp = 0;
            text= text.toUpperCase().replace(""+text.toUpperCase().charAt(i), "");
        
        }
    }

}