LinearLayout中Checkbox的最佳解决方案

Question

In my LinearLayout, there's a variable number of CheckBoxes. In a question I had a month ago someone said it´s better to add checkboxes dynamicly instead of make them not visible.

Integer[] count = new Integer[]{1,2,3,4,5,6,7,8,9,10};
size = mFrageList.get(position).getAuswahlList().size();
for (int i = 0; i < size; i++) {

    cBox = new CheckBox(this);
    cBox.setText(mFrageList.get(position).getAuswahlList().get(i));
    cBox.setId(count[i]);
    cBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

           if(isChecked){
                antwortencode[position] += "" + buttonView.getId();
                frageBeantworten.setText("Antwort :"+antwortencode[position]+" abgeben");

            } else {
                 String id = Integer.toString(buttonView.getId());
                 antwortencode[position] = antwortencode[position].replaceAll(id,"");
                 if(!antwortencode[position].isEmpty() || antwortencode[position]!= "") {
                     frageBeantworten.setText("Antwort :" + antwortencode[position] + " abgeben");
                  } else {
                      frageBeantworten.setText("Keine Checkbox(en) gewählt");
                  }
           }
       }
});

antworten.addView(cBox);

Currently, I'm able to save a string with the checked checkboxes, if I un-check a checkbox, it deletes it's value out of the string. If I update the activity, the string is saved, and the checkboxes get a new List from the mFrageList.get(position)getAuswahlList(); and fill a new string in the "antwortencode" List with their values.

If I go back to the last position, I have the string which was generated but the checkboxes aren't checked anymore. But they have the Strings from the old position. that means everything is saved except the state of the checkboxes. I cant set a cBox.setChecked(isChecked) or buttonView.setChecked(isChecked) or buttonView.setChecked(buttonView.isChecked()) or something which is nearly the same in syntax.

I don't know what I can do besides declaring 10 Checkboxes in a xml file to talk to them one by one and set the VISIBLE.false if the auswahlList.get(position).isEmpty().

IMPORTANT: My XML is a Scrollable Activity because the size of the content overextended the screen. Thats why i didn´t and can´t use a Listview. So i need a solution that uses a LinearLayout

Answer 1

The truth is, you should actually use a ListView . As long as you reuse a layout multiple times - do it.

There are 2 options:

• ListView as root - add other contents of your layout as different types of view

• ListView inside a scrollable layout - there are many lightweight implementations of ListView that allow it to wrap content, eg https://github.com/paolorotolo/ExpandableHeightListView

The other thing is how to maintain the state of Checkboxes - use model classes. It's extremely easy with a ListView as it forces you to use an Adapter which provides methods to iterate over all positions.

Example of an adapter:

public class CheckableItemAdapter extends BaseAdapter {

private List<Pair<Integer, Boolean>> items = new ArrayList<>();

public void setItems(List<Pair<Integer, Boolean>> items) {
    this.items = items;
}

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

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

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

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View view;
    ViewHolder holder;
    if (convertView == null) {
        view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_checkable, parent, false);
        holder = new ViewHolder(view);
        view.setTag(holder);
    } else {
        view = convertView;
        holder = (ViewHolder) view.getTag();
    }
    Pair<Integer, Boolean> item = items.get(position);
    holder.itemCheck.setChecked(item.second);
    return view;
}

static class ViewHolder {

    CheckBox itemCheck;

    public ViewHolder(View itemView) {
        itemCheck = (CheckBox) itemView.findViewById(R.id.check);
    }
}
}

Answer 2

I´ve managed to solve my problem alone, and now i want to share it, even if it isn´t the best example of programming.

  Integer[] count = new Integer[]{1,2,3,4,5,6,7,8,9,10}; //maximum of 10 Checkboxes
        size = mFrageList.get(position).getAuswahlList().size();
        for (int i = 0; i < size; i++) {
            cBox = new CheckBox(this);
            cBox.setText(mFrageList.get(position).getAuswahlList().get(i));
            cBox.setId(count[i]);

            try{ //this is where the magic happens
                if(antwortencode[position] != ""){ //cause i won´t want null in my db i´ve set "" as standard string in my activity for the List<String>
                    String code = antwortencode[position];
                    char[] c = code.toCharArray();
                    for(int j=0;j<=c.length;j++){
                        int x = c[j] -'0'; // 'char 1' - 'char 0' = Integer 1 , lol
                        if(cBox.getId()== x){ //compare them
                            cBox.toggle(); //if it fits, toggle
                        }
                    }
                }
            } catch (Exception e){
                    e.printStackTrace();
            } //and here it ends

            cBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

                    if(isChecked){
                        antwortencode[position] += "" + buttonView.getId();
                        frageBeantworten.setText("Antwort :"+antwortencode[position]+" abgeben");

                    } else {
                        String id = Integer.toString(buttonView.getId());
                        antwortencode[position] = antwortencode[position].replaceAll(id,"");
                        if(!antwortencode[position].isEmpty() || antwortencode[position]!= "") {
                            frageBeantworten.setText("Antwort :" + antwortencode[position] + " abgeben");
                        } else {
                            frageBeantworten.setText("Keine Checkbox(en) gewählt");
                        }
                    }
                }
            });

            antworten.addView(cBox);

Ty for the answers and for the correction of my question. Nostramärus