动态更改ListView的行布局

Question

我正在应用程序中的聊天模块,我希望来自两个参与者的消息反对对齐(其他用户左对齐和我自己的消息右对齐).现在,我的行布局通过静态布局xml传入(msg和avatar左对齐).有没有办法动态修改视图,或者有没有办法为UI系统传递备用行布局以便在运行时选择？

Answer 1

您可以在ArrayAdapter类的getView()方法中执行此操作(假设您正在定义自己的方法).ArrayAdapter

你可以这样:

private class YourAdapter extends ArrayAdapter<Message> {
        private final LayoutInflater mLayoutInflater;

    YourAdapter(YourListActivity activity) {
        super(mContext, 0);
        mLayoutInflater = LayoutInflater.from(activity);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            // Inflate your view
            convertView = mLayoutInflater.inflate(R.layout.list_view_item, parent, false);
            mViewHolder = new ViewHolder();
            mViewHolder.avatar = (ImageView) convertView.findViewById(R.id.placeholder);
            mViewHolder.message = (TextView) convertView.findViewById(R.id.message);

            convertView.setTag(mViewHolder);
        } else {
            mViewHolder = (ViewHolder) convertView.getTag();
        }

        final Message message = getItem(position);

        mViewHolder.message.setText(message.getMessage());
        // etc. Manipulate your views as you wish


        return convertView;
    }
}


   private static class ViewHolder {
        TextView message;
        ImageView avatar;
   }

getView每次ListView修改时都会调用(例如滚动时或添加新元素时),因此您可以根据需要操作每一行.不要忘记将数组适配器设置ListView为此类的实例.

listView.setListAdapter(new mYourAdapter);  

Answer 2

private LayoutInflater mInflater;
private static final int TYPE_ITEM1 = 0;
private static final int TYPE_ITEM2 = 1;
ArrayList<String> s= new ArrayList<String>();
int time;
String names[]={"raghu","pavan","rakesh","raghu","pavan"};
Context c;

@Override
public int getItemViewType(int position) {
    if((position%2)==0)
    {
        return 0;
    }
    return 1;       
}

@Override
public int getViewTypeCount() {
    return 2;
}

public Customlistadapter(CustomListView customListView, int time) {
    // TODO Auto-generated constructor stub
    for(int i=0;i<=10;i++)
    {
        s.add("Raghu");
    }
    this.mInflater = LayoutInflater.from(customListView);  
    c=customListView;
    this.time=time;
}
public int getCount() {
    return s.size();
}

public Object getItem(int arg0) {
    return s.get(arg0);
}

public long getItemId(int arg0) {
return 0;
}

@Override
public void notifyDataSetChanged() {
    super.notifyDataSetChanged();
    if(CustomListView.chk==true)
    {
    s.add("Raghu"); 
    }
    else if(CustomListView.chk==false)
    {
    s.remove(s.size()-1);
    }       
}
@Override
public void notifyDataSetInvalidated() {
    super.notifyDataSetInvalidated();
}
public View getView(final int arg0, View arg1, ViewGroup arg2) {
    ViewHolder vh;
    vh= new ViewHolder();
    int type = getItemViewType(arg0);
    System.out.println("getView " + arg0  + " type = "+type);
    if(arg1==null )
    {
         switch (type) {
         case TYPE_ITEM1:
             arg1=mInflater.inflate(R.layout.listview, arg2,false);             
            vh.tv= (TextView)arg1.findViewById(R.id.textView1);
            vh.tv1= (TextView)arg1.findViewById(R.id.textView2);
            vh.tv2=(TextView)arg1.findViewById(R.id.textView3);
            vh.tv.setText(s.get(arg0));
            vh.tv1.setText(s.get(arg0));
            vh.tv2.setText(Integer.toString(time));
             break;
         case TYPE_ITEM2:
             arg1=mInflater.inflate(R.layout.listviewimg, arg2,false);
            vh= new ViewHolder();
            vh.iv1= (ImageView)arg1.findViewById(R.id.iv1);
            vh.iv2= (ImageView)arg1.findViewById(R.id.iv2);
            vh.iv1.setBackgroundResource(R.drawable.ic_launcher);
            vh.iv2.setBackgroundResource(R.drawable.ic_launcher);
             break;
     }
        arg1.setTag(vh);
    }
    else
    {
        vh= (ViewHolder) arg1.getTag();
    }
    return arg1;
}

1.您的Cusom Adapter类扩展了基础适配器.2.覆盖getItemViewType()和getViewTypeCount()3.根据getView()中的类型对视图进行膨胀