Question

我有一个ListView项目的点数（纬度和经度），我想默认选择最接近的3个，并让用户用列表中的任何其他点切换这3个点中的任何一个点（主要的）用于空间插值的3点的目的。这是可能的，或者我怎样才能做出类似的东西？

示例：

用户处于适当位置（lat，lon）。 ListView包含项目（x1，y1），（x2，y2），（x3，y3），（x4，y4），......

应用程序默认选择3个最接近的用户位置项，例如3个第一项。现在用户必须能够用（x4，y4）切换例如（x1，y1）。

感谢。

Answer 1

检查我的解决方案。我试图创造你需要的答案。这很简单。

以下是代码：

适配器

public class Adapter extends BaseAdapter {

    private final LayoutInflater layoutInflater;
private final Context context;
public final ArrayList<PointItem> pointItems;

private int firstActivePointPosition;
private int secondActivePointPosition;
private int thirdActivePointPosition;

private int clickCounter;

public Adapter(Context context, ArrayList<PointItem> pointItems) {
    this.context = context;
    this.layoutInflater = LayoutInflater.from(context);
    this.pointItems = pointItems;

    //Default points
    this.pointItems.get(0).isChecked = true;
    this.pointItems.get(1).isChecked = true;
    this.pointItems.get(2).isChecked = true;

    this.firstActivePointPosition = 0;
    this.secondActivePointPosition = 1;
    this.thirdActivePointPosition = 2;
}

@Override
public int getCount() {
    return pointItems.size();
}

@Override
public Object getItem(int position) {
    return pointItems.get(position);
}

@Override
public long getItemId(int position) {
    return 0;
}


public void checkActivePosition(int position) {
    if (!this.pointItems.get(position).isChecked) {
        this.pointItems.get(position).isChecked = true;

        if (clickCounter == 0) {
            this.pointItems.get(this.firstActivePointPosition).isChecked = false;
            this.firstActivePointPosition = position;
        } else if (clickCounter == 1) {
            this.pointItems.get(this.secondActivePointPosition).isChecked = false;
            this.secondActivePointPosition = position;
        } else if (clickCounter == 2) {
            this.pointItems.get(this.thirdActivePointPosition).isChecked = false;
            this.thirdActivePointPosition = position;

            this.clickCounter = -1;
        }

        this.clickCounter++;
        notifyDataSetChanged();
    }
}

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        PointItem pointItem = (PointItem) getItem(position);

        ViewHolder viewHolder;

        if (convertView == null) {
            convertView = layoutInflater.inflate(R.layout.point_item_layout, null);
            viewHolder = new ViewHolder(convertView);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        viewHolder.title.setText(pointItem.title);

        if (pointItem.isChecked) {
            viewHolder.title.setBackgroundColor(Color.YELLOW);
        } else {
            viewHolder.title.setBackgroundColor(Color.TRANSPARENT);
        }

        return convertView;
    }

    public static class ViewHolder {
        public TextView title;

        public ViewHolder(View view) {
            this.title = (TextView) view.findViewById(R.id.txt_title);
        }
    }

    public static class PointItem {
        public int x;
        public int y;

        public String title;

        public boolean isChecked;

        public PointItem(int x, int y) {
            this.x = x;
            this.y = y;

            this.title = String.format("(%d, %d)", this.x, this.y);
        }
    }
}

初始化

ArrayList<Adapter.PointItem> pointItems = new ArrayList<>();
        pointItems.add(new Adapter.PointItem(0, 0));
        pointItems.add(new Adapter.PointItem(1, 1));
        pointItems.add(new Adapter.PointItem(2, 2));
        pointItems.add(new Adapter.PointItem(3, 3));
        pointItems.add(new Adapter.PointItem(4, 4));
        pointItems.add(new Adapter.PointItem(5, 5));
        pointItems.add(new Adapter.PointItem(6, 6));
        pointItems.add(new Adapter.PointItem(7, 7));
        pointItems.add(new Adapter.PointItem(8, 8));
        pointItems.add(new Adapter.PointItem(9, 9));

        Adapter adapter = new Adapter(getBaseContext(), pointItems);

        ListView listView = (ListView) findViewById(R.id.listView);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Adapter adapter = (Adapter) parent.getAdapter();
                adapter.checkActivePosition(position);
            }
        });

选择并切换android中的项目

1 个答案:

适配器

初始化