Can't set OnCheckedChangeListener to a Checkbox

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傲寒
傲寒 2021-01-02 01:01

I am trying to set a OnCheckedChangeListener to a CheckBox but my application exits in the run time. I also tried to set listeners for my Tex

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  •  清歌不尽
    2021-01-02 01:05

    You can't set the listener for your CheckBox from the ListView like that(it will probably throw a NullPointerException), instead set the listener in the getView() method(you'll also have to keep the CheckBox status so you don't end up with strange rows status). Bellow is an example:

    public class ListViewActivity extends ListActivity {
    
        public class MyCustomAdapter extends ArrayAdapter {
    
            private ArrayList status = new ArrayList();
    
            public MyCustomAdapter(Context context, int textViewResourceId,
                    String[] objects) {
                super(context, textViewResourceId, objects);
                for (int i = 0; i < objects.length; i++) {
                    status.add(false);
                }
            }
    
            @Override
            public View getView(final int position, View convertView,
                    ViewGroup parent) {
                View row = convertView;
                if (row == null) {
                    LayoutInflater inflater = getLayoutInflater();
                    row = inflater.inflate(R.layout.adapters_listviewactivity_row,
                            parent, false);
                }
    
                TextView label = (TextView) row.findViewById(R.id.weekofday);
                label.setText(month[position]);
                CheckBox checkBox = (CheckBox) row.findViewById(R.id.checkBox);
                checkBox.setOnCheckedChangeListener(new OnCheckedChangeListener() {
    
                    @Override
                    public void onCheckedChanged(CompoundButton buttonView,
                            boolean isChecked) {
                        Toast.makeText(getApplicationContext(), "" + position,
                                Toast.LENGTH_SHORT).show();
                        if (isChecked) {
                            status.set(position, true);
                        } else {
                            status.set(position, false);
                        }
                    }
                });
                checkBox.setChecked(status.get(position));
                return row;
            }
        }
    
        String[] month = { "January", "February", "March", "April", "May", "June",
                "July", "August", "September", "October", "November", "December" };
    
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setListAdapter(new MyCustomAdapter(ListViewActivity.this,
                    R.layout.main, month));
        }
    
    }
    

    For the TextView you'll have to do the same thing.

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