Java code that requires refactoring

Main.java

package uk.ac.chester;

public class Main {

    public static void main(String[] args) {

        System.out.println("Please type a phrase");
        java.util.Scanner scanner = new java.util.Scanner(System.in);
        String text = scanner.nextLine();
        text = text.toLowerCase();
        int countA = 0;
        int countE = 0;
        int countI = 0;
        int countO = 0;
        int countU = 0;
        for (int i = 0; i<text.length(); i++){
            char letter = text.charAt(i);
            switch (letter){
                case 'a':
                    countA++;
                    break;
                case 'e':
                    countE++;
                    break;
                case 'i':
                    countI++;
                    break;
                case 'o':
                    countO++;
                    break;
                case 'u':
                    countI++;
                    break;
                default:
                    break;
            }
        }

        char mostCommonVowel = 'a';
        int highCount = countA;
        if (countE > countA){
            mostCommonVowel = 'e';
            highCount = countE;
        }
        if (countI > highCount){
            mostCommonVowel = 'i';
            highCount = countI;
        }
        if (countO > highCount){
            mostCommonVowel = 'o';
            highCount = countO;
        }
        if (countU > highCount){
            mostCommonVowel = 'u';
            highCount = countU;
        }
        System.out.println("The most common vowel is: " + mostCommonVowel);
    }
}