How to toggle ListView item colors and Save it?

问题

I'm working on an Attendance app. The app has ListActivity consisting of a list of students. I want to change color to RED and GREEN indicating absent and present. The problem is if I have long list of students than screen. The items that are down or up the current view loses color. Is my approach correct? How can I save the color of each individual list item. Of course if there is another best approch other than using ListView, I'm open to suggestions.

Here is the ListActivity containing the list

public class ListActivity extends Activity implements Serializable{
private String userName;
private TextView nameTextView;
private ListView nameList;
private CustomAdapter adapter;
private boolean colorRed;
private Class myClass;

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

    myClass = new Class();
    colorRed = false;
//         Open the students list from file if exists
    openFromFile();

    nameList = (ListView) findViewById(R.id.nameListView);
    nameTextView = (TextView) findViewById(R.id.nameTextView);
    Bundle extras = getIntent().getExtras();
    if (extras != null) {
        userName = extras.getString("NAME");
        nameTextView.setText("Hi! " + userName);
    }

    adapter = new CustomAdapter(this, myClass.getStudentNames());
    nameList.setAdapter(adapter);
    TextView tv = (TextView) findViewById(R.id.sNametv);
    nameList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {

            if (colorRed == true) {
                view.setBackgroundColor(ContextCompat.getColor(getBaseContext(), R.color.colorPresent));
                colorRed = false;
            } else {
                view.setBackgroundColor(ContextCompat.getColor(getBaseContext(), R.color.colorAbsent));
                colorRed = true;
            }

//              ALso  could use this
//              adapterView.getChildAt(position).setBackgroundColor(Color.RED);

        }
    });
}

I'm using a boolean colorRed for checking color as I'm not able to compare view color with color from colors xml.

nameList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
            if (colorRed == true) {
                view.setBackgroundColor(ContextCompat.getColor(getBaseContext(), R.color.colorPresent));
                colorRed = false;
            } else {
                     view.setBackgroundColor(ContextCompat.getColor(getBaseContext(),    R.color.colorAbsent));
                colorRed = true;
            }
        }
    });

CustomAdapter Class for ListView

public class CustomAdapter extends ArrayAdapter<String> {

public CustomAdapter(Context context, ArrayList<String> names) {
    super(context, R.layout.custom_layout, names);

}

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

    LayoutInflater inflater = LayoutInflater.from(getContext());
    View customView = inflater.inflate(R.layout.custom_layout, parent, false);
    String singleName = getItem(position);
    TextView tv = (TextView) customView.findViewById(R.id.sNametv);
    tv.setText(singleName);

    return customView;
}
}

I've double checked it's a unique question! Rest Assured...

Thank You in Advance

回答1:

Create Listener Interface:

public interface ListListener {
     void clickListItem(int position);
}

Here is Model class:

public class Route {
    String studentName;
    boolean colorRed;

    public Route(String studentName, boolean colorRed) {
        this.studentName=studentName;
        this.colorRed=colorRed;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    public boolean isColorRed() {
        return colorRed;
    }

    public void setColorRed(boolean colorRed) {
        this.colorRed = colorRed;
    }
}

Create Adapter class:

public class AAdapter  extends BaseAdapter implements View.OnClickListener {

    Context context;
    private List<Route> routes;
    Holder holder;
    private static LayoutInflater inflater=null;
    ListListener listListener;

    public AAdapter(Context context, List<Route> names,ListListener listListener) {
       this.routes=names;
        this.context=context;
        this.listListener=listListener;
        inflater = ( LayoutInflater )context.
                getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public void onClick(View view) {
        listListener.clickListItem((Integer)view.getTag());
    }

    private class Holder
    {
        TextView tv;
    }

    @Override
    public Route getItem(int position) {
        return routes.get(position);
    }

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

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

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

        if (convertView==null){
            holder=new Holder();

            convertView=inflater.inflate(R.layout.custom_layout,null);

            holder.tv=(TextView)convertView.findViewById(R.id.textView);
            holder.tv.setOnClickListener(this);
            convertView.setTag(holder);

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

        holder.tv.setText(routes.get(position).getStudentName());
        holder.tv.setTag(position);

        if (!routes.get(position).colorRed){
            holder.tv.setBackgroundColor(Color.GREEN);
        }else {
            holder.tv.setBackgroundColor(Color.RED);
        }
        return convertView;
    }
}

Now MainActivity Class:

public class MainActivity extends AppCompatActivity implements ListListener{

    AAdapter adapter;
    ListView lv;
    List<Route> myNames;
    ListListener listListener=MainActivity.this;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv=(ListView)findViewById(R.id.listnames);


        myNames=new ArrayList<>();

        /* DEMO DATA U NEED TO FETCH YOUR DATA */
        myNames.add(new Route("FIRST",false));
        myNames.add(new Route("Second",false));
        myNames.add(new Route("Third",false));
        myNames.add(new Route("Fourth",false));
        myNames.add(new Route("Fifth",false));

        myNames.add(new Route("FIRST",false));
        myNames.add(new Route("Second",false));
        myNames.add(new Route("Third",false));
        myNames.add(new Route("Fourth",false));
        myNames.add(new Route("Fifth",false));

        myNames.add(new Route("FIRST",false));
        myNames.add(new Route("Second",false));
        myNames.add(new Route("Third",false));
        myNames.add(new Route("Fourth",false));
        myNames.add(new Route("Fifth",false));

        myNames.add(new Route("FIRST",false));
        myNames.add(new Route("Second",false));
        myNames.add(new Route("Third",false));
        myNames.add(new Route("Fourth",false));
        myNames.add(new Route("Fifth",false));


        adapter = new AAdapter(this, myNames,listListener);
        lv.setAdapter(adapter);
        adapter.notifyDataSetChanged();
    }

    @Override
    public void clickListItem(int position) {
        if(myNames.get(position).colorRed){
           myNames.get(position).colorRed=false;
        }else {
            myNames.get(position).colorRed=true;
        }
        adapter.notifyDataSetChanged();
    }
}

来源：https://stackoverflow.com/questions/40564450/how-to-toggle-listview-item-colors-and-save-it