如何在自定义对象的android中使用ArrayAdapter

Question

如何在Listview中使用自定义对象的属性.如果我使用字符串列表实现ArrayAdapter,它在Listview中显示正常,但是当我使用自定义对象列表时,它只输出内存地址.

我到目前为止的代码:

ArrayList<CustomObject> allObjects = new ArrayList<>();

allObjects.add("title", "http://url.com"));


  ArrayAdapter<NewsObject> adapter = new ArrayAdapter<NewsObject>(this,
                android.R.layout.simple_list_item_1, android.R.id.text1, allNews);


        // Assign adapter to ListView
        listView.setAdapter(adapter);


        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                Uri uri = Uri.parse( "http://www.google.com" );
                startActivity(new Intent(Intent.ACTION_VIEW, uri));
            }
        });

这里有一个类似的问题,但这不是我需要的,因为我只需要在列表视图中显示标题,然后点击提取网址.

Answer 1

ArrayAdapter显示toString()方法返回的值,因此您需要在自定义Object类中重写此方法以返回所需的String.您还需要至少具有URL的getter方法,以便您可以在click事件中检索该方法.

public class NewsObject {
    private String title;
    private String url;

    public NewsObject(String title, String url) {
        this.title = title;
        this.url = url;
    }

    public String getUrl() {
        return url;
    }

    @Override
    public String toString() {
        return title;
    }
    ...
}

在该onItemClick()方法中,position将是与您单击的列表项对应的自定义对象的ArrayList中的索引.检索URL,解析它并调用startActivity().

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            NewsObject item = allNews.get(position);
            String url = item.getUrl();
            Uri uri = Uri.parse(url);
            startActivity(new Intent(Intent.ACTION_VIEW, uri));
        }
    });

请注意,我假设您的自定义类是NewsObject,因为这是您的适配器示例使用的.

Answer 2

如果你想使用自定义类的方法，你需要实现一个 custor ArrayAdapter 类......如何创建它？

第一步

获取您的项目并创建一个新类。然后扩展类ArrayAdapter<YourObject>{}并在你需要的属性中声明......我的例子：

public class Room_Adapter extends ArrayAdapter<Room_Object> {

//Declaration of Atributes
private ArrayList<Room_Object> Rooms_Array;
private final Activity context;
private final ListView lvBuinding;

第二

为这个类声明一个构造函数，你总是需要一个 Activity 和 ArrayList，如果你需要，把它放在其他里面......在我的情况下，我需要列表视图......我的例子：

public Room_Adapter(Activity context, ArrayList<Room_Object> Rooms_Array,ListView lvBuinding) {
    super(context, R.layout.room_layout, Rooms_Array);

    this.context = context;
    this.Rooms_Array = Rooms_Array;
    this.lvBuinding = lvBuinding;
}

super 方法需要您的活动、自定义布局（如果有）和您的数组。

第三

如果您有自定义行布局，请声明一个静态类或创建一个新类。我的例子有一个静态类：

public static class Room_View{

    //Declaration of Atributes
    TextView RoomName;
    ImageView RoomState;
    TextView NoTroubles;

    Button btnRoomRow;

    ImageButton btnShowRoomTasks;
    ImageButton btnAddTasks;

    RelativeLayout RowLayout;
}

第四

覆盖方法 getView。

@Override
public View getView(int position, View ConvertView, ViewGroup parent) {

    //Declaration of Variables
    Room_View rowView; //Custom static class with controls
    LayoutInflater inflator = context.getLayoutInflater();

    if (ConvertView == null) {
        rowView = new Room_View();
        ConvertView = inflator.inflate(R.layout.room_layout,null,true); //Inflate your view with your custom view.


        rowView.RoomName = (TextView) ConvertView.findViewById(R.id.txtvRoom);
        rowView.RoomState = (ImageView) ConvertView.findViewById(R.id.ivRoomState);
        rowView.NoTroubles = (TextView) ConvertView.findViewById(R.id.txtvNoTroubles);

        rowView.btnRoomRow = (Button) ConvertView.findViewById(R.id.btnRoomRow);

        rowView.btnAddTasks = (ImageButton) ConvertView.findViewById(R.id.btnAddTask);
        rowView.btnShowRoomTasks = (ImageButton) ConvertView.findViewById(R.id.btnShowRoomTasks);

        rowView.RowLayout = (RelativeLayout) ConvertView.findViewById(R.id.rowLayout);


        ConvertView.setTag(rowView);
    }
    else
    {
        rowView = (Room_View) ConvertView.getTag();
    }

    //Here custom your control stats
    Room_Object Room = Rooms_Array.get(position);
    rowView.RoomName.setText(Room.getRoomName());

    rowView.NoTroubles.setVisibility(View.INVISIBLE);
    rowView.btnShowRoomTasks.setClickable(true);
    rowView.btnShowRoomTasks.setImageResource(R.drawable.list_3a4b66_50);
    rowView.btnShowRoomTasks.setOnClickListener(OnShowTasksClickListener);

    //This is for add ClickListiner in my buttons...
    rowView.btnAddTasks.setOnClickListener(OnAddTasksClickListener);
    rowView.btnRoomRow.setOnClickListener(OnAddTasksClickListener);

    if(Room.getStatus().equals("Checked")){
        rowView.RowLayout.setBackgroundColor(0xFFC7E6C7);
        rowView.btnShowRoomTasks.setClickable(false);
        rowView.btnShowRoomTasks.setImageResource(R.drawable.list_999999_50);
        rowView.RoomState.setImageResource(R.drawable.check_3ebf4b_50);
    }
    else if(Room.getStatus().equals("Blocked")){
        rowView.RowLayout.setBackgroundColor(0xFFDBC3E5);
        rowView.RoomState.setImageResource(R.drawable.key_9330e0_50);
    }
    else if(Room.getStatus().equals("Dirty")){
        rowView.RowLayout.setBackgroundColor(0xfffceedb);
        rowView.RoomState.setImageResource(R.drawable.icon_housekeeping_3_yellow);
    }
    else if(Room.getStatus().equals("Troubled")){
        rowView.RowLayout.setBackgroundColor(0xFFF4CECD);
        rowView.RoomState.setImageResource(R.drawable.wrench_eb3232_50);

        rowView.NoTroubles.setVisibility(View.VISIBLE);
        try {
            rowView.NoTroubles.setText(Integer.toString(Room.getNoTasks()));
        }
        catch (Exception ex){
            Log.e("-- Error --",ex.getMessage());
        }
    }

    //
    //Pay attention *************************************************
    //

    //Now if you needs to use your custom external class this is the site, now imagine that you need gets string from your custom class in the text view, then:

    //Declare class
    CustomClass object = new CustomClass();

    rowView.(CUSTOM CONTROL FROM YOUR STATIC CLASS).(METHOD OF CONTROL)(object.(CUSTOM METHOD OF YOUR OBJECT));

    //For example If you follows my sample then:
    rowView.NoTroubles.setText(object.getNumberOfTroubles().toString);


    return ConvertView;
}

//Listener Methods for my button controls
private View.OnClickListener OnShowTasksClickListener = new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        int positionSelected = lvBuinding.getPositionForView((View) v.getParent());
        int totalRooms = lvBuinding.getCount() - 1;
        int actualRoom = totalRooms - positionSelected;

        try{
            //Your code;
        }
        catch (Exception ex){
            Log.e("-- CustomError --", ex.getMessage());
        }
    }
};

private View.OnClickListener OnAddTasksClickListener = new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        int positionSelected = lvBuinding.getPositionForView((View) v.getParent());
        int totalRooms = lvBuinding.getCount() - 1;
        int actualRoom = totalRooms - positionSelected;

        try{
            //Your code;
        }
        catch (Exception ex){
            Log.e("-- CustomError --", ex.getMessage());
        }
    }
};
}

我认为这是您需要的，如果您需要更多信息或同样的建议，我会尽力帮助您...祝您好运，Eduardo！