android - How to get selected list items from a Listview with checkBox and Custom Adapter?

Question

I have a ListView with CheckBox on it. and i am using Custom Adapter to populate the ListView.

In my xml file i have a Button at bottom. what i want is let user select number of rows in ListView and when he/she clicked on the Button get the position of the selected items so that i could get the object for particular row for further calculations.

Answer 1

Below Snippet does exactly what you want.

package com.windrealm.android;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class PlanetsActivity extends Activity
{

    private ListView mainListView;
    private Planet[] planets;
    private ArrayAdapter<Planet> listAdapter;
    private Button check;
    private Context context;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        context = PlanetsActivity.this;
        check = (Button) findViewById(R.id.check);
        // Find the ListView resource.
        mainListView = (ListView) findViewById(R.id.mainListView);

        // When item is tapped, toggle checked properties of CheckBox and
        // Planet.
        mainListView
                .setOnItemClickListener(new AdapterView.OnItemClickListener()
                {
                    @Override
                    public void onItemClick(AdapterView<?> parent, View item,
                            int position, long id)
                    {
                        Planet planet = listAdapter.getItem(position);
                        planet.toggleChecked();
                        PlanetViewHolder viewHolder = (PlanetViewHolder) item
                                .getTag();
                        viewHolder.getCheckBox().setChecked(planet.isChecked());
                    }
                });

        // Create and populate planets.
        planets = (Planet[]) getLastNonConfigurationInstance();
        if (planets == null)
        {
            planets = new Planet[]
            { new Planet("Mercury"), new Planet("Venus"), new Planet("Earth"),
                    new Planet("Mars"), new Planet("Jupiter"),
                    new Planet("Saturn"), new Planet("Uranus"),
                    new Planet("Neptune"), new Planet("Ceres"),
                    new Planet("Pluto"), new Planet("Haumea"),
                    new Planet("Makemake"), new Planet("Eris") };
        }
        ArrayList<Planet> planetList = new ArrayList<Planet>();
        planetList.addAll(Arrays.asList(planets));

        // Set our custom array adapter as the ListView's adapter.
        listAdapter = new PlanetArrayAdapter(this, planetList);
        mainListView.setAdapter(listAdapter);

        check.setOnClickListener(new OnClickListener()
        {

            @Override
            public void onClick(View view)
            {
                for (int i = 0; i < listAdapter.getCount(); i++)
                {
                    Planet planet = listAdapter.getItem(i);
                    if (planet.isChecked())
                    {
                        Toast.makeText(context,
                                planet.getName() + " is Checked!!",
                                Toast.LENGTH_SHORT).show();
                    }
                }

            }
        });
    }

    /** Holds planet data. */
    private static class Planet
    {
        private String name = "";
        private boolean checked = false;

        public Planet()
        {
        }

        public Planet(String name)
        {
            this.name = name;
        }

        public Planet(String name, boolean checked)
        {
            this.name = name;
            this.checked = checked;
        }

        public String getName()
        {
            return name;
        }

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

        public boolean isChecked()
        {
            return checked;
        }

        public void setChecked(boolean checked)
        {
            this.checked = checked;
        }

        public String toString()
        {
            return name;
        }

        public void toggleChecked()
        {
            checked = !checked;
        }
    }

    /** Holds child views for one row. */
    private static class PlanetViewHolder
    {
        private CheckBox checkBox;
        private TextView textView;

        public PlanetViewHolder()
        {
        }

        public PlanetViewHolder(TextView textView, CheckBox checkBox)
        {
            this.checkBox = checkBox;
            this.textView = textView;
        }

        public CheckBox getCheckBox()
        {
            return checkBox;
        }

        public void setCheckBox(CheckBox checkBox)
        {
            this.checkBox = checkBox;
        }

        public TextView getTextView()
        {
            return textView;
        }

        public void setTextView(TextView textView)
        {
            this.textView = textView;
        }
    }

    /** Custom adapter for displaying an array of Planet objects. */
    private static class PlanetArrayAdapter extends ArrayAdapter<Planet>
    {

        private LayoutInflater inflater;

        public PlanetArrayAdapter(Context context, List<Planet> planetList)
        {
            super(context, R.layout.simplerow, R.id.rowTextView, planetList);
            // Cache the LayoutInflate to avoid asking for a new one each time.
            inflater = LayoutInflater.from(context);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent)
        {
            // Planet to display
            Planet planet = (Planet) this.getItem(position);

            // The child views in each row.
            CheckBox checkBox;
            TextView textView;

            // Create a new row view
            if (convertView == null)
            {
                convertView = inflater.inflate(R.layout.simplerow, null);

                // Find the child views.
                textView = (TextView) convertView
                        .findViewById(R.id.rowTextView);
                checkBox = (CheckBox) convertView.findViewById(R.id.CheckBox01);

                // Optimization: Tag the row with it's child views, so we don't
                // have to
                // call findViewById() later when we reuse the row.
                convertView.setTag(new PlanetViewHolder(textView, checkBox));

                // If CheckBox is toggled, update the planet it is tagged with.
                checkBox.setOnClickListener(new View.OnClickListener()
                {
                    public void onClick(View v)
                    {
                        CheckBox cb = (CheckBox) v;
                        Planet planet = (Planet) cb.getTag();
                        planet.setChecked(cb.isChecked());
                    }
                });
            }
            // Reuse existing row view
            else
            {
                // Because we use a ViewHolder, we avoid having to call
                // findViewById().
                PlanetViewHolder viewHolder = (PlanetViewHolder) convertView
                        .getTag();
                checkBox = viewHolder.getCheckBox();
                textView = viewHolder.getTextView();
            }

            // Tag the CheckBox with the Planet it is displaying, so that we can
            // access the planet in onClick() when the CheckBox is toggled.
            checkBox.setTag(planet);

            // Display planet data
            checkBox.setChecked(planet.isChecked());
            textView.setText(planet.getName());

            return convertView;
        }

    }

    public Object onRetainNonConfigurationInstance()
    {
        return planets;
    }
}