Android 带有复选框的列表视图填充了对象

Question

以下代码是从数据库中获取的项目列表，我应该选择对象并通过按下按钮将它们显示在另一个列表视图中。请在给定情况下帮助我提供建议。谢谢！

public class ParticipantsSelectedActivity extends AppCompatActivity implements View.OnClickListener{

DataBaseHandler myDb;
ListView listViewParticipants;
ParticipantsSelectedListAdapter participantsSelectedListAdapter;
Participants participants;
Button btn_save_participants_selected;
CheckBox ckb;

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

    myDb = new DataBaseHandler(this);
    ckb = (CheckBox)findViewById(R.id.ckb);

    listViewParticipants = (ListView) findViewById(R.id.listViewParticipantsSelected);
    btn_save_participants_selected = (Button) findViewById(R.id.btn_save_participants_selected);

    final ArrayList<Participants> listData = new ArrayList<>();
    final Cursor cursor = myDb.getListParticipants();

    if(cursor.getCount() == 0){
        Toast.makeText(this, "There is no participants", Toast.LENGTH_SHORT).show();
    }else {
        while(cursor.moveToNext()){
            int id =(Integer.valueOf(cursor.getString(0)));
            String firstName = cursor.getString(1);
            String position = cursor.getString(3);

            participants = new Participants(id,firstName,position, true);
            listData.add(participants);


            participantsSelectedListAdapter = new ParticipantsSelectedListAdapter(this,android.R.layout.simple_list_item_multiple_choice,listData);
            listViewParticipants.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
            listViewParticipants.setAdapter(participantsSelectedListAdapter);
            btn_save_participants_selected.setOnClickListener(this);

        }

    }
        /*

    listViewParticipants.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Participants participants = listData.get(position);

            Toast.makeText(getApplicationContext(), "Clicked on Id..." + participants.getId(), Toast.LENGTH_SHORT).show();
        }
    });

    */

}


@Override
public void onClick(View v) {
    //another activity to fill another listView
}



}

这是自定义适配器

public class ParticipantsSelectedListAdapter extends ArrayAdapter<Participants> {

public ParticipantsSelectedListAdapter(Context context,int a, ArrayList<Participants> participants) {
    super(context, 0, participants);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    // Get the data item for this position
    Participants participants = getItem(position);
    // Check if an existing view is being reused, otherwise inflate the view
    if (convertView == null) {
        convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_participants_selected, parent, false);
    }
    // Lookup view for data population
    TextView tvFirstName = (TextView) convertView.findViewById(R.id.tvFirstName);
    TextView tvPosition = (TextView) convertView.findViewById(R.id.tvPosition);
    CheckBox ckb = (CheckBox) convertView.findViewById(R.id.ckb);

    // Populate the data into the template view using the data object
    tvFirstName.setText(participants.getFirstName());
    tvPosition.setText(participants.getPosition());
    ckb.setChecked(false);

    // Return the completed view to render on screen

    return convertView;
}

}

这是 XML 项

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <CheckBox
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:focusable="false"
        android:id="@+id/ckb"/>
    <TextView
        android:id="@+id/tvFirstName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/tvPosition"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

Answer 1

在您的模型 class 中，为参与者添加一个这样的布尔变量以进行选择和取消选择：

在Participant.class

private boolean isSelected;

public void setSelected(boolean selection){
this.isSelected = selection;
}

public boolean isSelected(){
this.isSelected;
}

在数据库数据检索上，您一次又一次地设置适配器是错误的，不需要这样做。添加了 OnClick 事件以从参与者列表中获取选定的项目。

public class ParticipantsSelectedActivity extends AppCompatActivity implements View.OnClickListener {

    DataBaseHandler myDb;
    ListView listViewParticipants;
    ParticipantsSelectedListAdapter participantsSelectedListAdapter;
    Participants participants;
    Button btn_save_participants_selected;
    CheckBox ckb;
    final ArrayList<Participants> listData = new ArrayList<>();

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

        myDb = new DataBaseHandler(this);
        ckb = (CheckBox) findViewById(R.id.ckb);

        listViewParticipants = (ListView) findViewById(R.id.listViewParticipantsSelected);
        btn_save_participants_selected = (Button) findViewById(R.id.btn_save_participants_selected);


        final Cursor cursor = myDb.getListParticipants();

        if (cursor.getCount() == 0) {
            Toast.makeText(this, "There is no participants", Toast.LENGTH_SHORT).show();
        } else {
            while (cursor.moveToNext()) {
                int id = (Integer.valueOf(cursor.getString(0)));
                String firstName = cursor.getString(1);
                String position = cursor.getString(3);

                participants = new Participants(id, firstName, position, true);
                listData.add(participants);
            }

            //Setting adapter after all data retrieve from database
            participantsSelectedListAdapter = new ParticipantsSelectedListAdapter(this, android.R.layout.simple_list_item_multiple_choice, listData);
            listViewParticipants.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
            listViewParticipants.setAdapter(participantsSelectedListAdapter);
            btn_save_participants_selected.setOnClickListener(this);

        }
        /*

    listViewParticipants.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Participants participants = listData.get(position);

            Toast.makeText(getApplicationContext(), "Clicked on Id..." + participants.getId(), Toast.LENGTH_SHORT).show();
        }
    });

    */

    }

    @Override
    public void onClick(View v) {
        //another activity to fill another listView
        if (v.getId() == R.id.btn_save_participants_selected) {
            ArrayList<Participants> selectedListData = new ArrayList<>();
            if (listData != null && listData.size() > 0) {
                for (int i = 0; i < listData.size(); i++) {
                    if (listData.get(i).isSelected()) {
                        selectedListData.add(listData.get(i));
                    }
                }
                //Pass this selectedListData to new activity to show a new Listview
            }
        }

    }
}

选择和取消选择的适配器代码发生变化。

public ParticipantsSelectedListAdapter(Context context, int a, ArrayList<Participants> participants) {
        super(context, 0, participants);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Get the data item for this position
        final Participants participants = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        if (convertView == null) {
            convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_participants_selected, parent, false);
        }
        // Lookup view for data population
        TextView tvFirstName = (TextView) convertView.findViewById(R.id.tvFirstName);
        TextView tvPosition = (TextView) convertView.findViewById(R.id.tvPosition);
        CheckBox ckb = (CheckBox) convertView.findViewById(R.id.ckb);

        // Populate the data into the template view using the data object
        tvFirstName.setText(participants.getFirstName());
        tvPosition.setText(participants.getPosition());

        if(participants.isSelected) {
            ckb.setChecked(true);
        }else {
            ckb.setChecked(false);
        }

        ckb.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                participants.setSelected(!participants.isSelected());
                notifyDataSetChanged();
            }
        });

        // Return the completed view to render on screen

        return convertView;
    }

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