Question

我有一个列表片段，其中每个项目都包含一个复选框，用户可以选中并取消选中它。列表片段中的每个项目对应于类Task中的对象，该对象存储有关是否选中该复选框的信息。

我的问题是，如何修改Task对象以响应复选框的选中和取消选中？我知道您通常会创建一个Task对象，然后通知适配器以便UI响应更改，但是如何反转该过程？

列表片段：

public class ListViewDemoFragment extends ListFragment {
private static List<Task> mItems;        // ListView items list
private ListViewDemoAdapter mAdapter;
private IntentFilter intfil;
private DataBaseWrapper db;

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    mItems = new ArrayList<Task>();
    intfil = new IntentFilter("CUSTOM");
    db = new DataBaseWrapper(getActivity());
    mItems = db.getAllTasks();
    mAdapter = new ListViewDemoAdapter(getActivity(), mItems);
    setListAdapter(mAdapter);
    getListView().setOnItemLongClickListener(new OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
                                       int arg2, long arg3) {
            mItems.remove(arg2);
            mAdapter.notifyDataSetChanged();
            return true;
        }
    });
}

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    // remove the dividers from the ListView of the ListFragment
    getListView().setDivider(null);
}

@Override
public void onListItemClick(ListView l, View v, int position, long id) {
    // retrieve theListView item
    Task item = mItems.get(position);
    Toast.makeText(getActivity(), item.title, Toast.LENGTH_SHORT).show();
}

private BroadcastReceiver b = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String name = intent.getStringExtra("name");
        String dline = intent.getStringExtra("dline");
        int pri = intent.getIntExtra("pri", 2);
        //String des = intent.getStringExtra("des");
        Task t = new Task(pri, name, dline, false);
        mItems.add(t);
        mAdapter.notifyDataSetChanged();
        db.addTask(t);
    }
};


public void onResume() {
    super.onResume();
    getActivity().registerReceiver(b, intfil);
}

public void onDestroy() {
    super.onDestroy();
    getActivity().unregisterReceiver(b);
}

public void onPause() {
    super.onPause();
    db.close();
}

public List<Task> getlist() {
    return mItems;
}

}

适配器：

public class ListViewDemoAdapter extends ArrayAdapter<Task> {

public ListViewDemoAdapter(Context context, List<Task> items) {
    super(context, R.layout.listview_item, items);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    final ViewHolder viewHolder;

    if (convertView == null) {
        // inflate the GridView item layout
        LayoutInflater inflater = LayoutInflater.from(getContext());
        convertView = inflater.inflate(R.layout.listview_item, parent, false);

        // initialize the view holder
        viewHolder = new ViewHolder();
        viewHolder.ivIcon = (ImageView) convertView.findViewById(R.id.ivIcon);
        viewHolder.tvTitle = (TextView) convertView.findViewById(R.id.tvTitle);
        viewHolder.tvDescription = (TextView) convertView.findViewById(R.id.tvDescription);
        viewHolder.checkbox = (CheckBox) convertView.findViewById(R.id.checkbox);
        convertView.setTag(viewHolder);
    } else {
        // recycle the already inflated view
        viewHolder = (ViewHolder) convertView.getTag();
    }

    // update the item view
    Task item = getItem(position);
    Drawable d = null;
    switch (item.icon) {
        case 0:
            d = ContextCompat.getDrawable(getContext(), R.drawable.red);
            break;
        case 1:
            d = ContextCompat.getDrawable(getContext(), R.drawable.yellow);
            break;
        case 2:
            d = ContextCompat.getDrawable(getContext(), R.drawable.green);
            break;
    }
    viewHolder.ivIcon.setImageDrawable(d);
    viewHolder.tvTitle.setText(item.title);
    viewHolder.tvDescription.setText(item.deadline);
    viewHolder.checkbox.setChecked(item.check);
    return convertView;
    }

            /**
             * The view holder design pattern prevents using findViewById()
             * repeatedly in the getView() method of the adapter.
             */
    private static class ViewHolder {
    ImageView ivIcon;
    TextView tvTitle;
    TextView tvDescription;
    CheckBox checkbox;
}

}

任务类（列表中的项目）

public Task(int icon, String title, String deadline,boolean check) {
    this.icon = icon;
    this.title = title;
    this.deadline = deadline;
    this.check = check;
}


public String getName()
{return title;}

public int getIcon()
{return icon;}

public String getDeadline()
{return deadline;}

public boolean getCheck()
{return check;}

public void setCheck(Boolean b )
{
    check = b;
}

}

主要活动

public class MainActivity extends FragmentActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

public void add(View view) {
    startActivityForResult(new Intent(MainActivity.this, TaskInput.class), 1);
}

public void save(View view)
{
    DataBaseWrapper db = new DataBaseWrapper(this);
    db.deleteAll();
    ListViewDemoFragment f = (ListViewDemoFragment)getFragmentManager().findFragmentById(R.id.frag);
    for (Task item: f.getlist())
    {
        db.addTask(item);
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
    super.onActivityResult(requestCode, resultCode, data);
    if(requestCode==1)
    {
       sendBroadcast(data);
    }
}

Answer 1

尝试修改适配器，如下所示：

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    final ViewHolder viewHolder;

    final Task item = getItem(position);

    if (convertView == null) {
        // inflate the GridView item layout
        LayoutInflater inflater = LayoutInflater.from(getContext());
        convertView = inflater.inflate(R.layout.listview_item, parent, false);

        // initialize the view holder
        viewHolder = new ViewHolder();
        viewHolder.ivIcon = (ImageView) convertView.findViewById(R.id.ivIcon);
        viewHolder.tvTitle = (TextView) convertView.findViewById(R.id.tvTitle);
        viewHolder.tvDescription = (TextView) convertView.findViewById(R.id.tvDescription);
        viewHolder.checkbox = (CheckBox) convertView.findViewById(R.id.checkbox);
        viewHolder.checkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                item.setCheck(isChecked);
            }
        });
        convertView.setTag(viewHolder);
    } else {
        // recycle the already inflated view
        viewHolder = (ViewHolder) convertView.getTag();
    }

    Drawable d = null;
    switch (item.icon) {
        case 0:
            d = ContextCompat.getDrawable(getContext(), R.drawable.red);
            break;
        case 1:
            d = ContextCompat.getDrawable(getContext(), R.drawable.yellow);
            break;
        case 2:
            d = ContextCompat.getDrawable(getContext(), R.drawable.green);
            break;
    }
    viewHolder.ivIcon.setImageDrawable(d);
    viewHolder.tvTitle.setText(item.title);
    viewHolder.tvDescription.setText(item.deadline);
    viewHolder.checkbox.setChecked(item.check);
    return convertView;
}

在更改的listfragment中存储数据

1 个答案: