Android自定义ListView复选框保存状态

Question

I need to be able to save the state of the checkboxes. When the app the closes, it should save which checkboxes were checked and when the app comes back on, the checkboxes that were checked should be checked at startup. It uses a custom adapter listview. Thank You for your time.

public class OrderActivity extends AppCompatActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_order);

        getSupportActionBar().setTitle("Order");
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        ListView listview;
        CustomChoiceListViewAdapter adapter;
        adapter = new CustomChoiceListViewAdapter();
        listview = (ListView) findViewById(R.id.listview1);
        listview.setAdapter(adapter);

        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a1), "1");
        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a2), "2");
        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a3), "3");
        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a4), "4");
        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a5), "5");
        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a6), "6");
        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a7), "7");
        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a8), "8");
        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a9), "9");
        adapter.addItem(ContextCompat.getDrawable(this, R.drawable.a10), "10");
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                finish();
                return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

.

public class ListViewItem {
    private Drawable icon;
    private String text;

    public void setIcon(Drawable icon) {
        this.icon = icon;
    }

    public void setText(String text) {
        this.text = text;
    }

    public Drawable getIcon() {
        return this.icon;
    }

    public String getText() {
        return this.text;
    }
}

.

public class CustomChoiceListViewAdapter extends BaseAdapter{

    private ArrayList<ListViewItem> listViewItemList = new ArrayList<ListViewItem>() ;
    public CustomChoiceListViewAdapter() { }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        final int pos = position;
        final Context context = parent.getContext();

        if (convertView == null) {
            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.item_order, parent, false);
        }

        ImageView iconImageView = (ImageView) convertView.findViewById(R.id.imageview1) ;
        TextView textTextView = (TextView) convertView.findViewById(R.id.text_name) ;

        ListViewItem listViewItem = listViewItemList.get(position);

        iconImageView.setImageDrawable(listViewItem.getIcon());
        textTextView.setText(listViewItem.getText());

        return convertView;
    }

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


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

    public void addItem(Drawable icon, String text) {
        ListViewItem item = new ListViewItem();

        item.setIcon(icon);
        item.setText(text);

        listViewItemList.add(item);
    }
}

.

public class CheckableLinearLayout extends LinearLayout implements Checkable {

    public CheckableLinearLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        // mIsChecked = false ;
    }

    @Override
    public boolean isChecked() {
        CheckBox cb = (CheckBox) findViewById(R.id.checkBox1);
        return cb.isChecked();
        // return mIsChecked ;
    }

    @Override
    public void toggle() {
        CheckBox cb = (CheckBox) findViewById(R.id.checkBox1);
        setChecked(cb.isChecked() ? false : true);
        // setChecked(mIsChecked ? false : true) ;
    }

    @Override
    public void setChecked(boolean checked) {
        CheckBox cb = (CheckBox) findViewById(R.id.checkBox1);

        if (cb.isChecked() != checked) {
            cb.setChecked(checked);
        }


    }
}

Answer 1

You can use SharedPreferences to store states of your checkboxes for later use. However, you need to have identification number for each checkbox to do this. Store it in this form: ".12.32.54.62." where 12, 32, 54, 62 are identification numbers of checked boxes. Reading and writing to SharedPreferences file may take some time, but I don't think it will affect your performance that much. On the other hand, I think there is room for improvement in below code:

public class CheckableLinearLayout extends LinearLayout implements Checkable {

String mId;
SharedPreferences mShPreferences;

public CheckableLinearLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
    mShPreferences = context.getSharedPreferences(
            "com.yourpackagename.PREFERENCE_FILE_KEY", Context.MODE_PRIVATE);
}

@Override
public boolean isChecked() {
    CheckBox cb = (CheckBox) findViewById(R.id.checkBox1);
    String key = "." + mId + ".";
    return mShPreferences.getString("checkboxes", cb.isChecked() ? key : "").contains(key);
}

@Override
public void toggle() {
    CheckBox cb = (CheckBox) findViewById(R.id.checkBox1);
    setChecked(!cb.isChecked());
}

@Override
public void setChecked(boolean checked) {
    CheckBox cb = (CheckBox) findViewById(R.id.checkBox1);

    if (cb.isChecked() != checked) {

        cb.setChecked(checked);

        String checkboxes = mShPreferences.getString("checkboxes", ".");

        SharedPreferences.Editor editor = mShPreferences.edit();

        String key = "." + mId + ".";

        if (checked && !checkboxes.contains(key))
            editor.putString("checkboxes", checkboxes + mId + ".");
        else if (!checked && checkboxes.contains(key))
            editor.putString("checkboxes", checkboxes.replace(key, "."));

        editor.apply();
    }
}

public void setId(String id) {
    this.mId = id;
}
}