Question

my application on the first lunch uses 6.5mb, and then when I enter an activity with 3 tabs, with a tab that displays a listview, it uses 14 mb!!

This happened when I went from a “bad code” with SimpleAdapter to my Custom Adapter.

What I want is 2 strings on each side in a listview. the strings are in an array, here is the way I was using that people told me is an incorrect way to do:

String[] array= getResources().getStringArray(R.array.Names_List);

int lengthtmp= array.length;
for(int i=0;i<lengthtmp;i++)
{
    counter++;
    AddToList(array[i]);            
}

adapter = new SimpleAdapter(this,list,R.layout.start_row,new String[] {"number","suraname"},new int[] {R.id.Start_Numbering,R.id.Start_Name});


private void AddToList(String name) {
HashMap<String,String> temp = new HashMap<String,String>();


temp.put("number", Integer.toString(SortingPictures[counter-1]));

temp.put("suraname", name);
list.add(temp);

  }

With this code, the activity takes 10mb of ram. After changing my code to use a Custom adapter, it uses 14 mb:

 public class ListView_Start_Adapter extends BaseAdapter{
private String[] SuraNames;
private int[] PageNumber;
private Context mContext;
RelativeLayout relativeView;
TextView tv_SuraName;
TextView tv_PageNumber;
RelativeLayout.LayoutParams param;

public ListView_Start_Adapter(Context context, String[] SuraNames, int[] PageNumber){
    mContext=context;
    this.SuraNames=SuraNames;
    this.PageNumber=PageNumber;
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return SuraNames.length;
}

@Override
public Object getItem(int arg0) {
    // TODO Auto-generated method stub
    return SuraNames[arg0];
}

@Override
public long getItemId(int arg0) {
    // TODO Auto-generated method stub
    return PageNumber[arg0];
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub
    relativeView= new RelativeLayout(mContext);
    tv_SuraName = new TextView(mContext);
    tv_PageNumber = new TextView(mContext);

    tv_SuraName.setText(SuraNames[position]);
    tv_PageNumber.setText(Integer.toString(PageNumber[position]));

    param = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.FILL_PARENT, RelativeLayout.LayoutParams.FILL_PARENT);
    param.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);

    relativeView.addView(tv_SuraName, param);
    relativeView.addView(tv_PageNumber);

    return relativeView;

}

  }

Can anyone tell me why so much ram used when using a Custom adapter? Is there something wrong with this Custom adapter?

EDIT1: Is this a better code that the one suggested by dziobas:

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

    if(convertView == null) {
        convertView = mInflater.inflate(R.layout.start_row, parent,false);
        holder=new ViewHolder();

        holder.tv_SuraName   =(TextView)convertView.findViewById(R.id.Start_Name);
        holder.tv_PageNumber = (TextView)convertView.findViewById(R.id.Start_Numbering);
        convertView.setTag(holder);
    } else {
        holder  = (ViewHolder) convertView.getTag();
    }

    holder.tv_SuraName.setText(SuraNames[position]);
    holder.tv_PageNumber.setText(Integer.toString(PageNumber[position]));

    return convertView;
}

I get ExceptionNullPointer in this line: ” convertView = mInflater.inflate(R.layout.start_row, parent,false);
” Why?

Answer 1

You’re not recycling view in getView.

It’ll much better like this:

public class ListView_Start_Adapter extends BaseAdapter {
    private String[]            SuraNames;
    private int[]               PageNumber;
    RelativeLayout.LayoutParams param;
    Context                     mContext;

    public ListView_Start_Adapter(Context context, String[] SuraNames, int[] PageNumber) {
        mContext        = context;
        this.SuraNames  = SuraNames;
        this.PageNumber = PageNumber;
        param           = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.FILL_PARENT, RelativeLayout.LayoutParams.FILL_PARENT);
        param.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
    }

    @Override
    public int getCount() {
        return SuraNames.length;
    }

    @Override
    public Object getItem(int arg0) {
        return SuraNames[arg0];
    }

    @Override
    public long getItemId(int arg0) {
        return PageNumber[arg0];
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder     holder;
        RelativeLayout rowView;

        if(convertView == null) {
            //create view
            rowView              = new RelativeLayout(mContext);
            holder               = new ViewHolder();
            holder.tv_SuraName   = new TextView(mContext);
            holder.tv_PageNumber = new TextView(mContext);
            rowView.addView(holder.tv_SuraName, param);
            rowView.addView(holder.tv_PageNumber);
            rowView.setTag(holder);
        } else {
            //recycle view
            rowView = (RelativeLayout) convertView;
            holder  = (ViewHolder) convertView.getTag();
        }

        //fill views
        holder.tv_SuraName.setText(SuraNames[position]);
        holder.tv_PageNumber.setText(Integer.toString(PageNumber[position]));

        return rowView;
    }

    class ViewHolder {
        RelativeLayout relativeView;
        TextView       tv_SuraName;
        TextView       tv_PageNumber;
    }
}

And change view creation. Use LayoutInflater and use xml for layout.

See this presentation for more info about listview adapter efficiency.