java - 如何从数组列表中删除元素？

Question

所以我想询问用户是否想从数组列表中删除一个元素。数组列表是从文件中读入的最喜欢的颜色的列表。假设数组列表的内容是 - 红、橙、绿、蓝。我想知道如何根据用户输入删除元素。会不会是这样的 -

System.in.println("Which color would you like to remove")
removeColor = reader.nextString
if removeColor (//using pseudo code here) contains removeColor, remove from ArrayList

我走在正确的道路上吗？到目前为止，这是我的代码。谢谢!

Scanner input = new Scanner(System.in);
        ArrayList <String> favoriteColors = new ArrayList <String>();
        boolean repeat = true;
        while (repeat) {

            System.out.println("Enter the name of the file which contains your favorite colors ");
            String fileName = input.nextLine().trim();

            try (BufferedReader reader = new BufferedReader(new FileReader(fileName))) {

                String line;
                System.out.println("Here are your favorite colors according to the file:");  
                 while ((line = reader.readLine()) != null) {    
                   System.out.println(line);   
                   favoriteColors.add((line));
                 }                                                

                 System.out.println("Add more? (y/n)");
                 if (input.next().startsWith("y")) {
                     System.out.println("Enter : ");
                     favoriteColors.add(input.next());
                 } else {
                     System.out.println("have a nice day");
                 }
                 for (int i = 0; i < favoriteColors.size(); i++) {
                     System.out.println(favoriteColors
                 if (input.next().startsWith("y")) {
                 System.out.println("Remove a color?")
                 if (input.next().startsWith("y")) {
                 /something along the lines of the pseudo code I wrote above

Answer 1

您需要了解 ArrayList 中的删除方法如何工作:

remove方法的实现如下:

public boolean remove(Object o) {
    if (o == null) {
        for (int index = 0; index < size; index++)
            if (elementData[index] == null) {
                fastRemove(index);
                return true;
            }
    } else {
        for (int index = 0; index < size; index++)
            if (o.equals(elementData[index])) {
                fastRemove(index);
                return true;
            }
    }
    return false;
}

than 表示列表中包含的对象必须能够实现此条件:

if (o.equals(elementData[index])) {

因此:

如果您的favoriteColors类只是字符串，那么它就可以工作

但是如果它们是您定制的，那么您需要在该类中实现 equals。