java - 从对象数组中删除对象

Question

我正在使用 java 处理对象数组。

我已经完成了添加，它有效。我在实现删除(从数组中)时遇到问题。

对象来自名为 Student 的类，它有一个名称和 ID 作为成员

我的工作:

// delete an object
if (count == 0)
    System.out.println("Sorry there are no items in the system");
else {
    System.out.print("Please enter the ID of Student you'd like to Delete: "); 
    String searchID = in.nextLine();
    for (int i =1 ; i<count; i++) { // first : search for the object 
        if (searchID.equalsIgnoreCase(Students[i].getID())) {
            System.out.print("Are you sure you want do delete " 
                    + Students[i].getName()+ " from the System? ");
            String ans = in.nextLine();
            if (ans.equalsIgnoreCase("no")) { break; }
            if (ans.equalsIgnoreCase("yes")) { 
                Students[i] = Students[Students.length-1];
                break;
            }
        } else {
            System.out.println("Sorry, you need to type a valid ID to delete it's object.. ");
        }                     
    }

Answer 1

首先我无法理解你的代码的逻辑。您应该在收到用户的 100*2 输入之前检查答案。不管怎样，如果你真的想用简单的java数组来做到这一点，你应该这样做，然后删除空对象。这是一种低效的方法:

    String[] a = {"student1", "student2"};
    String[] b = {"strudnt3"};
    String[] c = new String[a.length + b.length];
    // removing one object
    a[1] = null;
    // copying both arrays to c
    System.arraycopy(a, 0, c, 0, a.length);
    System.arraycopy(b, 0, c, a.length, b.length);
    // ignore null objects
    System.out.println(Arrays.toString(c));

更好的方法是使用ArrayList:您可以轻松地从列表中添加和删除对象。在这里查看 JavaDoc http://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html

如果你想用ArrayList重写代码:

    // creat an ArrayList of the object
    ArrayList<Student> studentList = new ArrayList<Student>();

    // then, ask if the user wants to add object
    Scanner in = new Scanner (System.in);
    System.out.print("Would you like to add an object?");

    while (true) {
        String ans = in.nextLine();
        if (ans.equals("no")) 
        {
            break;
        }
        // else, create the object and add it to the ArrayList
        // you can add the attributes from the constructor
        studentList.add(new Student(22, "name"));
    }

然后您可以轻松地创建一个迭代器，在列表中执行循环并匹配您想要的任何字段，最后从列表中删除对象:

    if (//find the object) {
        studentList.remove(object)
    }

另请检查此问题以从 ArrayList 中删除对象: remove an object from a List