Question

我拥有的内容：带有Textviews和复选框的自定义列表视图 问题：如果我检查屏幕上显示的初始项目然后滚动列表，当我返回列表顶部（向上滚动）时，它们的值被正确保存。但是，如果我滚动列表，例如我想检查列表中的最后一个树复选框，那么如果我上下滚动它们就会被取消选中....为什么？**
我已经在其他论坛中看到了针对同一问题的各种解决方案，也在stackoverflow上看到过，但问题仍然存在在我的getView函数下面，我认为没问题：

    @Override
      public View getView(final int position, View convertView, ViewGroup parent) {
    final ViewHolder viewHolder;
    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.item_select_friends, null);
        viewHolder=new ViewHolder();
        viewHolder.nameText=(TextView) convertView.findViewById(R.id.personName);
        viewHolder.surnameText=(TextView) convertView.findViewById(R.id.personSurname);
        viewHolder.contactImage=(ImageView) convertView.findViewById(R.id.personImage);
        viewHolder.checkBox=(CheckBox)convertView.findViewById(R.id.checkBox);

        convertView.setTag(viewHolder);

        viewHolder.nameText.setTag(viewHolder.nameText);
        viewHolder.nameText.setTag(viewHolder.surnameText);
        viewHolder.contactImage.setTag(data[position]);
        viewHolder.checkBox.setChecked(data[position].isCheck());  
        viewHolder.checkBox.setOnClickListener(new OnClickListener() {  

            public void onClick(View arg0) {  

                if(viewHolder.checkBox.isChecked()==true)   
                    data[position].setCheck(true);  
                else  
                    data[position].setCheck(false);  
            }  
        });
    }
    else{
        viewHolder = (ViewHolder) convertView.getTag();
    }

    viewHolder.nameText.setText(data[position].getName());
    viewHolder.surnameText.setText(data[position].getSurname());
    viewHolder.contactImage.setImageResource(data[position].getPhotoRes());
    viewHolder.contactImage.setScaleType(ScaleType.FIT_XY);
    viewHolder.checkBox.setChecked(data[position].isCheck());
    return convertView;
}

已解决：我解决了我的问题getView whit这段代码：

    public class NewQAAdapterSelectFriends extends BaseAdapter {
private LayoutInflater mInflater;
private Person[] data;
boolean[] checkBoxState;
ViewHolder viewHolder;

public NewQAAdapterSelectFriends(Context context) { 
    mInflater = LayoutInflater.from(context);
}


public void setData(Person[] data) {
    this.data = data;
    checkBoxState=new boolean[data.length];
}

@Override
public int getCount() {
    return data.length;
}

@Override
public Object getItem(int item) {
    return data[item];
}

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



@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.item_select_friends, null);
        viewHolder=new ViewHolder();

        viewHolder.nameText=(TextView) convertView.findViewById(R.id.personName);
        viewHolder.surnameText=(TextView) convertView.findViewById(R.id.personSurname);
        viewHolder.contactImage=(ImageView) convertView.findViewById(R.id.personImage);
        viewHolder.checkBox=(CheckBox)convertView.findViewById(R.id.checkBox);

        convertView.setTag(viewHolder);

    }
    else{
        viewHolder = (ViewHolder) convertView.getTag();
    }

    viewHolder.nameText.setText(data[position].getName());
    viewHolder.surnameText.setText(data[position].getSurname());
    viewHolder.contactImage.setImageResource(data[position].getPhotoRes());
    viewHolder.contactImage.setScaleType(ScaleType.FIT_XY);
    viewHolder.checkBox.setChecked(checkBoxState[position]);
    viewHolder.checkBox.setOnClickListener(new View.OnClickListener() {

           public void onClick(View v) {
               if(((CheckBox)v).isChecked()){
                   checkBoxState[position]=true;
                   data[position].setCheck(true);
               }else{
                   checkBoxState[position]=false;
                   data[position].setCheck(false);
               }
            }
        });
    return convertView;
}


static class ViewHolder {
    TextView nameText;
    TextView surnameText;
    ImageView contactImage;
    CheckBox checkBox;
}

}

我已经看过这个教程来做我的getView：http://androidcocktail.blogspot.it/2012/04/adding-checkboxes-to-custom-listview-in.html

Answer 1

即使在方法中使用new创建类，也为变量创建了不同的范围。换句话说：

// Creating a new scope here -->       vvv
viewHolder.checkBox.setOnClickListener(new OnClickListener() {
    // Any variables not visible to the entire class, won't work properly in here! 
    //  (variables like: viewHolder, position, possibly data) 
    public void onClick(View arg0) {  
        if(viewHolder.checkBox.isChecked()==true)   
            data[position].setCheck(true);  
        else  
            data[position].setCheck(false);  
    }  
}); // Exited "new class'" scope

position与您认为的position不同。请尝试保存position的值，以便再次引用它：

viewHolder.checkBox = (CheckBox) convertView.findViewById(R.id.checkBox);
viewHolder.position = position;
convertView.setTag(viewHolder);
...

viewHolder.checkBox.setOnClickListener(new OnClickListener() {  
    public void onClick(View view) {
        ViewHolder viewHolder = (ViewHolder) view.getTag();
        data[viewHolder.position].setCheck(viewHolder.checkBox.isChecked());   
    }  
});

由于您正在处理CheckBox，我建议您使用OnCheckedChangeListener。

但如果更改ChoiceMode，则可能不需要为ListView行定义任何侦听器：

listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);

Answer 2

在viewHolder.checkBox.setChecked(checkBoxState[position]);或viewHolder.checkBox.setOnCheckedChangedListener之后添加viewHolder.checkBox.setOnClickListener。

因为在滚动之后，当listview回收它的视图时，它会在旧的侦听器的基础上使用setChecked，在某些情况下可能会丢失值。

所以这是流程 -

getView()
---
---
---
viewHolder.checkBox.setOnCheckedChangedListener()
---
---
---
viewHolder.checkBox.setChecked()

Answer 3

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder>
{
    boolean[] checkBoxState;


    public MyAdapter(Context context, ArrayList<String> list ) {
        checkBoxState = new boolean[list.size()];
    }

    @Override
    public void onBindViewHolder( final ViewHolder holder,  final int position) {
        holder.checkBox.setTag(position); 

            holder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener(){
                @Override
                public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
                    if(compoundButton.isPressed()) // check whether user pressed the checkbox.
                    {
                        int getPosition = (Integer) compoundButton.getTag();  // Here we get the position that we have set for the checkbox using setTag.
                        checkBoxState[getPosition] = compoundButton.isChecked(); // Set the value of checkbox to maintain its state.
                    }
                }
            });

            holder.checkBox.setChecked(checkBoxState[position]);
    }   

    public class ViewHolder extends RecyclerView.ViewHolder  {
        public CheckBox checkBox;
        public ViewHolder(View v,MainActivity mainActivity) {
            super(v);
            checkBox= (CheckBox) v.findViewById(R.id.checkBox);
        }
    }

    @Override
    public int getItemCount() {
        return list.size();
    }
}

滚动时，可以自动调用onCheckedChanged（）方法。因此，您可能需要使用isPressed（）方法来检查用户是否按下了复选框。我的适配器类如上所示。请注意，当您向列表中添加新元素时，应更新布尔数组checkBoxState，例如，当您向列表中添加元素时，应调用以下内容：

checkBoxState = new boolean[list.size()+1];

或使用arraylist来保存布尔变量并向此arraylist添加元素，无论你想要什么。

我还为此解决方案实施了一个项目。你可以在这里下载： https://www.dropbox.com/s/ssm58w62gw32i29/recyclerView_checkbox_highlight.zip?dl=0

屏幕截图如下：

滚动我的自定义ListView时，复选框丢失了选中的值

3 个答案: