如何从一个void方法中跳出并返回到switch方法？

public static void decrypt() throws FileNotFoundException {
    Scanner kbrd = new Scanner(System.in);
    System.out.println("Enter Key-file name: ");
    String filename = kbrd.nextLine();
    System.out.println("Enter Message-filename: ");
    String mssgFilename = kbrd.nextLine();
    String[] keyArray = loadMessage(filename);
    String[] message = loadMessage(mssgFilename);
    String[] cipher = xor2(message, keyArray);
    String readable = showText(cipher);
    System.out.println("The text:" + readable);
    return;
}

接下来是切换方法

System.out.println("Encrypt  1.");
    System.out.println("Decrypt  2.");
    System.out.println("Make Key 3.");
    System.out.println("Quit     4.");
    Scanner scan = new Scanner(System.in);
    String choice = scan.nextLine();
    do {
        switch (choice) {
        case "1":
            encrypt();
            break;
        case "2":
            decrypt();
            break;
        case "3":
            makeKey();
            break;
        }
    } while (choice != "4");

问题是，不管我选择什么，它都会停留在那个方法中，尽管最后有return语句，这不应该让我回到switch方法吗？