删除重复项后对 alpha 进行排序的方法 java（集合）

Question

Working with collections and arraylists in java and writing a method to take user input (list) and put it into a method that removes the duplicates and then sorts the list alphabetically to print. The method I have written successfully removes duplicates, but will not sort alphabetically. Here is my method body:

public static void sortNoDups(ArrayList<String> list) {
        // e
        ArrayList<String> printedList = new ArrayList<>();
        System.out.println("\nWithout duplicates, sorted alphabetically:");
        for (String i : list) {
            if (!printedList.contains(i)) {
                printedList.add(i);
                Collections.sort(printedList);
                System.out.print(i + " ");

            }
        }
        System.out.println();
    }

I have also tried it without the line "Collections.sort(printedList)", and with "Collections.sort(list)" to no avail. Happy to include additional code from above if needed, but felt I should start specific to see if there are any glaring errors I'm just missing.

Answer 1

Your code is fine – it is correctly sorting printedList – but you aren't actually printing that out. Right now, your code is iterating through the original list . The thing you are printing is System.out.print(i + " "); which is just printing the next string from list .

To print the contents of the sorted printedList , add this to the end of your method:

for (String s : printedList) {
    System.out.println(s);
}

Also, you might want to move Collections.sort(printedList) to the end of the method as well. That way, you'll call sort one time at the end, instead of calling it each time in your for loop.