记住listview

Question

我使用自定义适配器，布局和模型类的listview（包含文本和复选框）。我想在sqlite db中保存选中的复选框，这样当我导航到另一个活动然后返回时，所选的复选框仍保持选中状态。

public class MainActivity extends AppCompatActivity {

    MyCustomAdapter dataAdapter = null;


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

        displayListView();

        checkButtonClick();


    }

    private void displayListView()
    {

        //Array list of countries
        ArrayList<States> stateList = new ArrayList<States>();

        States _states = new States("AP","Andhra Pradesh",false);
        stateList.add(_states);
        _states = new States("DL","Delhi",true);
        stateList.add(_states);
        _states = new States("GA","Goa",false);
        stateList.add(_states);
        _states = new States("JK","Jammu & Kashmir",true);
        stateList.add(_states);
        _states = new States("KA","Karnataka",true);
        stateList.add(_states);
        _states = new States("KL","Kerala",false);
        stateList.add(_states);
        _states = new States("RJ","Rajasthan",false);
        stateList.add(_states);
        _states = new States("WB","West Bengal",false);
        stateList.add(_states);

        //create an ArrayAdaptar from the String Array
        dataAdapter = new MyCustomAdapter(this,R.layout.state_info, stateList);
        ListView listView = (ListView) findViewById(R.id.listView1);
        // Assign adapter to ListView
        listView.setAdapter(dataAdapter);

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener()
        {

            public void onItemClick(AdapterView<?> parent, View view, int position, long id)
            {
                // When clicked, show a toast with the TextView text
                States state = (States) parent.getItemAtPosition(position);
                Toast.makeText(getApplicationContext(),"Clicked on Row: " + state.getName(),
                        Toast.LENGTH_LONG).show();
            }
        });
    }

    private void checkButtonClick()
    {

        Button myButton = (Button) findViewById(R.id.findSelected);

        myButton.setOnClickListener(new View.OnClickListener()
        {

            @Override
            public void onClick(View v)
            {

                StringBuffer responseText = new StringBuffer();
                responseText.append("The following were selected...\n");

                ArrayList<States> stateList = dataAdapter.stateList;

                for(int i=0;i<stateList.size();i++)
                {
                    States state = stateList.get(i);

                    if(state.isSelected())
                    {
                        responseText.append("\n" + state.getName());
                    }
                }

                Toast.makeText(getApplicationContext(),
                        responseText, Toast.LENGTH_LONG).show();
            }
        });
    }


}

public class MyCustomAdapter extends ArrayAdapter<States> {

    public ArrayList<States> stateList;

    public MyCustomAdapter(Context context, int textViewResourceId, ArrayList<States> stateList)
    {
        super(context, textViewResourceId, stateList);
        this.stateList = new ArrayList<States>();
        this.stateList.addAll(stateList);
    }

    private class ViewHolder
    {
        TextView code;
        CheckBox name;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {

        ViewHolder holder = null;

        Log.v("ConvertView", String.valueOf(position));

        if (convertView == null)
        {

            LayoutInflater vi = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);

            convertView = vi.inflate(R.layout.state_info, null);

            holder = new ViewHolder();
            holder.code = (TextView) convertView.findViewById(R.id.code);
            holder.name = (CheckBox) convertView.findViewById(R.id.checkBox1);

            convertView.setTag(holder);

            holder.name.setOnClickListener( new View.OnClickListener()
            {
                public void onClick(View v)
                {
                    CheckBox cb = (CheckBox) v;
                    States _state = (States) cb.getTag();

                 /*   Toast.makeText(getApplicationContext(), "Clicked on Checkbox: " + cb.getText() + " is " + cb.isChecked(),
                            Toast.LENGTH_LONG).show();*/

                    _state.setSelected(cb.isChecked());
                }
            });

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

        States state = stateList.get(position);

        holder.code.setText(" (" + state.getCode() + ")");
        holder.name.setText(state.getName());
        holder.name.setChecked(state.isSelected());

        holder.name.setTag(state);

        return convertView;
    }

}

public class States {

    String code = null;
    String name = null;
    boolean selected = false;

    public States(String code, String name, boolean selected) {
        this.code = code;
        this.name = name;
        this.selected = selected;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public boolean isSelected() {
        return selected;
    }

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

Answer 1

Use Realm instead of Sqlite.

//在模型类中 公共类状态扩展了RealmObject {

String code = null;
String name = null;
boolean selected = false;

public States(String code, String name, boolean selected) {
    this.code = code;
    this.name = name;
    this.selected = selected;
}

public String getCode() {
    return code;
}

public void setCode(String code) {
    this.code = code;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public boolean isSelected() {
    return selected;
}

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

}`

//在适配器类中

RealmResults results = realm.where（States.class）.findAll（）;

            // Get the book title to show it in toast message
            States state = results.get(position);

           holder.code.setText(" (" + state.getCode() + ")");
           holder.name.setText(state.getName());
           holder.name.setChecked(state.isSelected());

           holder.name.setTag(state);

您可以按照以下链接了解如何在android studio中使用realm

use realm database example 1

use realm database example 2

Answer 2

There are two more ways like :

use android sqlite

use Shared Preference