Question

    boolean run = true;
    while(true)
    {
        System.out.println("Enter A to add, S to search, E to exit");
        String temp = input.next();
    switch(temp)
    {
        case "A":
        case "a":
            System.out.println("Please enter the building name: ");
            newClassroom.setBuildingName(input.next());
            System.out.println("Please enter the room number: ");
            newClassroom.setRoomNumber(input.next());
            System.out.println("Please enter the capacity: ");
            newClassroom.setCapacity(input.nextInt());
            System.out.println("Please enter the academic department: ");
            newClassroom.setAcadDept(input.next());
            System.out.println("Please enter whether or not the room has a projector: ");
            newClassroom.setProjector(input.nextBoolean());
            List.add(newClassroom);
            break;
        case "S":
        case "s":
            System.out.println("Enter the building name and room number you wish to locate");
            //String buildingSearch = input.next();
            //int roomSearch = input.nextInt();
            System.out.println(List);
            //System.out.println(buildingSearch + roomSearch);
            Classroom temporary = new Classroom();
            temporary.setBuildingName(input.next());
            temporary.setRoomNumber(input.next());

            break;
        case "E":
        case "e":
            System.exit(0);
    }
    }
}

我正在尝试检查并查看ArrayList中是否包含对象。我尝试过使用contains，但有人说我应该尝试使用.equals（）代替。

Answer 1

两者都是必需的。您必须覆盖equals()类中的ClassRoom方法，该方法与其他ClassRoom对象进行比较，例如房间号（取决于您将如何实现它）。现在，当调用contains()方法时，它将通过调用ClassRoom方法并比较Room no来检查每个equals()对象。如果它已经存在，它将返回true。

class ClassRoom {
     int roomNo;

     public ClassRoom(int r) {
        // TODO Auto-generated constructor stub
         this.roomNo = r;
    }
    @Override
    public boolean equals(Object obj) {
        // TODO Auto-generated method stub
        ClassRoom cr = (ClassRoom)obj;
        return this.roomNo == cr.roomNo;
    }
 }

class TestContains {
    public static void main(String[] args)  {
        ClassRoom c1 = new ClassRoom(5);
        ClassRoom c2 = new ClassRoom(6);
        ClassRoom c3 = new ClassRoom(7);
        List<ClassRoom> list = new ArrayList<ClassRoom>();
        list.add(c1);
        list.add(c2);
        list.add(c3);

        ClassRoom c8 = new ClassRoom(8);
        ClassRoom c7 = new ClassRoom(7);
        System.out.println(list.contains(c8));
        System.out.println(list.contains(c7));



    }
}

输出：

假

真

检查输入对象是否包含在arrayList中

1 个答案: