我创建一个自定义的ListView。我试着优化我的ListView的适配器的getView方法，但我仍然遇到滞后。

I've created a custom ListView. I've tried to optimize the getView method of my ListView's Adapter but I'm still experiencing lag.

我是什么在导致我的ListView滞后适配器做错了？

What am I doing wrong in the Adapter that causes my ListView to lag?

或者，如果它看起来不错，这可能是造成的滞后？

Or if it looks good, what could be causing the lag?

一排ListView中的XML是：

The xml of a row in the ListView is:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="6dip"
android:background="@color/all_white"
android:orientation="vertical">
<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:padding="6dip"
    android:background="@color/all_white"
    android:gravity="center">
   <TextView
    android:layout_width="40dip"
    android:layout_height="wrap_content"
    android:paddingTop="10dip"
    android:paddingBottom="10dip"
    />
<Button
    android:layout_width="197dip"
    android:layout_height="wrap_content"
    android:layout_marginRight="8dip"
    android:paddingTop="10dip"  
    android:paddingBottom="10dip"
    android:background="@drawable/button_300"
    android:textColor="@color/all_white"     
    />
<Button
    android:layout_width="197dip"
    android:layout_height="wrap_content"
    android:layout_marginRight="8dip"
    android:paddingTop="10dip"  
    android:paddingBottom="10dip" 
    android:background="@drawable/button_300"
    android:textColor="@color/all_white"     
    />
<Button
    android:layout_width="197dip"
    android:layout_height="wrap_content"
    android:layout_marginRight="8dip"
    android:paddingTop="10dip"  
    android:paddingBottom="10dip" 
    android:background="@drawable/button_300"
    android:textColor="@color/all_white"
    />
<Button
    android:layout_width="197dip"
    android:layout_height="wrap_content"
    android:layout_marginRight="8dip"
    android:paddingTop="10dip"  
    android:paddingBottom="10dip" 
    android:background="@drawable/button_300"
    android:textColor="@color/all_white"        
    />    
<Button
    android:layout_width="197dip"
    android:layout_height="wrap_content"
    android:layout_marginRight="8dip"
    android:paddingTop="10dip"  
    android:paddingBottom="10dip" 
    android:background="@drawable/button_300"
    android:textColor="@color/all_white"
    />
<Button
    android:layout_width="197dip"
    android:layout_height="wrap_content"
    android:layout_marginRight="8dip"
    android:paddingTop="10dip"  
    android:paddingBottom="10dip" 
    android:background="@drawable/button_300"
    android:textColor="@color/all_white"        
    />   
</LinearLayout>
</LinearLayout>

在code为我的适配器是：

The code for my Adapter is:

公共类MultiWorkspaceAdapter2延伸BaseAdapter {

public class MultiWorkspaceAdapter2 extends BaseAdapter {

/*
 * A map of the workspaces of a user, with key == first letter of the workspace title
 * and value == the list of WorkspaceInfos for that key.
 */
private LinkedHashMap<String, List<WorkspaceInfo>> _workspacesMap;

/*
 * Array of keys in order to get the values in getItem.
 */
private String[] _keys;

private Activity _activity;

public MultiWorkspaceAdapter2(Activity activity, LinkedHashMap<String,     List<WorkspaceInfo>> map) {
    _workspacesMap = map;
    _keys = (String[]) _workspacesMap.keySet().toArray(new String[_workspacesMap.size()]);
    _activity = activity;
}

public int getCount() {
    return _workspacesMap.size();
}

public Object getItem(int position) {
    _keys = (String[]) _workspacesMap.keySet().toArray(new String[_workspacesMap.size()]);
    List<WorkspaceInfo> list = new ArrayList<WorkspaceInfo>();
    try {
        if (_keys[position] != null) {
        list = _workspacesMap.get(_keys[position]);
        }
    } catch (ArrayIndexOutOfBoundsException e) {
        list = null;
    }
    return list;
}

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

public View getView(int position, View convertView, ViewGroup parent) {
    ViewGroup viewGroup = null;
    int numRows = 0;

    if (convertView != null) {
        viewGroup = (ViewGroup) convertView; 
    } else {
        LayoutInflater inflater = (LayoutInflater) _activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        viewGroup = (ViewGroup) inflater.inflate(R.layout.multi_workspace_layout, parent, false);

        _keys = (String[]) _workspacesMap.keySet().toArray(new String[_workspacesMap.size()]);
        List<WorkspaceInfo> workspaces = new ArrayList<WorkspaceInfo>();
        try {
            if (_keys[position] != null) {
                workspaces = _workspacesMap.get(_keys[position]);
                //Collections.sort(workspaces, new InfoNameComparator());
            }
        } catch (ArrayIndexOutOfBoundsException e) {
            //
        }

        numRows = viewGroup.getChildCount();

        //Find how many buttons are in a row.
        int buttonsInRow = ((ViewGroup) viewGroup.getChildAt(0)).getChildCount();

        int totalRows = 0;
        int size = workspaces.size();
        if (size > 0) {
            totalRows = size / buttonsInRow + 1;
        }

        if (numRows < totalRows) {
            for (int i = numRows; i < totalRows; i++) {
                View view;
                LayoutInflater inflater2 = (LayoutInflater) _activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                view = (View) inflater2.inflate(R.layout.list_row_multi_ws, viewGroup, false);
                viewGroup.addView(view, i);
            }
        } else if (numRows > totalRows) {
            for (int i = numRows; i > totalRows; i--) {
                viewGroup.removeViewAt(totalRows);
            }
        }

        //Iterate over workspaces
        Iterator<WorkspaceInfo> iterator = workspaces.iterator();
        for (int i = 0; i < viewGroup.getChildCount(); i++) {
            //Linear layout child containing buttons and textview.
            ViewGroup temp = (ViewGroup) viewGroup.getChildAt(i);
            for (int j = 0; j < temp.getChildCount(); j++) {
                if (j == 0) {
                    //The letter these workspaces start with
                    TextView textview = (TextView) temp.getChildAt(j);
                    String letter = _keys[position];
                    textview.setText(_keys[position]);
                    if (i != 0 && temp.getId() != R.id.workspaces_portrait) {
                        textview.setVisibility(View.INVISIBLE);
                    } else if (i != 0) {
                        textview.setVisibility(View.GONE);
                    }
                } else {
                    //A workspace button
                    Button button = (Button) temp.getChildAt(j);
                    if (iterator.hasNext()) {
                        //Get the next workspace
                        final WorkspaceInfo workspace = iterator.next();
                        //Get the title of the workspace and set as text.
                        String buttonText = workspace.getTitle();
                        button.setText(buttonText);
                        button.setVisibility(View.VISIBLE);
                        //Add OnClickListener
                        button.setOnClickListener(new OnClickListener() {
                            public void onClick(View v) {
                                //If the workspace is pending,  handle the invitation.
                                if (workspace.getStatus() == StaticFields.PENDING_WORKSPACE) {
                                    ((SkootWorkspacesActivity) _activity).handleInvitation(workspace);
                                } else {
                                    //open the workspace
                                    ((SkootWorkspacesActivity) _activity).openWorkspace(workspace);
                                }
                            }
                          });
                        button.setOnLongClickListener(new OnLongClickListener() {
                            public boolean onLongClick(View v) {
                                ((SkootWorkspacesActivity) _activity).makeDeleteDialog(workspace);
                                return true;
                            }
                          });
                    } else {
                        button.setVisibility(View.GONE);
                    }
                }
            }
        }

    }
    return viewGroup;
}

我这个适配器添加到MergeAdapter和做与MergeAdapter ListView的setAdapter。

I add this adapter to a MergeAdapter and do setAdapter on the ListView with the MergeAdapter.

感谢

推荐答案

有关问题的最佳解决方案（ListView的滞后）是持有人即使用Holder类样品code

The Best solution for your problem (ListView to lag) is Holder i.e using Holder class Sample code

在适配器类创建ViewHolder类的对象构造

Create an object for ViewHolder class in the Adapter class Constructor

ViewHolder支架=新ViewHolder（）;

ViewHolder holder=new ViewHolder();

public View getView(int position, View convertView, ViewGroup parent) {
        AppInfo entry = mListAppInfo.get(position);
        ViewHolder holder = null;

        if(convertView == null) {
            LayoutInflater inflater = LayoutInflater.from(mContext);
            convertView = inflater.inflate(R.layout.layout_appinfo, null);
            holder = new ViewHolder();
            holder.ivIcon = (ImageView)convertView.findViewById(R.id.ivIcon);
            holder.tvName = (TextView)convertView.findViewById(R.id.tvName);
            convertView.setTag(holder);
        }
        else {
            holder = (ViewHolder)convertView.getTag();
        }

        holder.ivIcon.setImageBitmap(entry.getIcon());
        holder.tvName.setText(entry.getName());

        return convertView;
    }

    static class ViewHolder {
        ImageView ivIcon;
        TextView tvName;
    }