动态更改ListView的行布局

Question

我正在应用程序中的聊天模块上工作，我希望来自两名参与者的反向对齐消息（其他用户左对齐，而我自己的消息右对齐）。现在，我的行布局通过静态布局xml传递（msg和avatar左对齐）。有没有办法动态地修改视图，还是有办法通过UI系统的替代行布局在运行时选择？

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ArrayAdapter）。

你可能有这样的事情：

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会得到您每次ListView被修改时（当您滚动或当新的元素添加到它像）叫，所以你可以操纵的每一行 如你所愿。 不要忘记将ListView的阵列适配器设置为此类的一个实例。

listView.setListAdapter(new mYourAdapter); 

Answer 2

我已经显示出这样做的一种方式（林不知道，如果它的最佳实践或不！）是在一个XML文件，这两种观点。在运行时，您可以获取对每个视图的引用（使用findViewById）并将可见属性设置为不想要的视图属性。

我试着找到一些示例代码，如果不清楚？

Answer 3

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Base Adapter。 2.覆盖getItemViewType（）和getViewTypeCount（） 3.充气取决于类型getView（）视图

Answer 4

我的代码：

private void setAlignment(ViewHolder holder, boolean isOutgoing, QBChatMessage chatMessage) { 

    if (!isOutgoing) { 
     LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) holder.contentWithBG.getLayoutParams(); 
     layoutParams.gravity = Gravity.LEFT; 
     holder.contentWithBG.setLayoutParams(layoutParams); 

     RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) holder.content.getLayoutParams(); 
     lp.addRule(RelativeLayout.ALIGN_PARENT_LEFT, 0); 
     lp.addRule(RelativeLayout.ALIGN_PARENT_RIGHT); 
     holder.content.setLayoutParams(lp); 

     layoutParams = (LinearLayout.LayoutParams) holder.txtInfo.getLayoutParams(); 
     layoutParams.gravity = Gravity.RIGHT; 
     holder.txtInfo.setLayoutParams(layoutParams); 

     if (holder.txtMessage != null) { 
      holder.contentWithBG.setBackgroundResource(R.drawable.bubblevioletcopy); 
      layoutParams = (LinearLayout.LayoutParams) holder.txtMessage.getLayoutParams(); 
      layoutParams.gravity = Gravity.RIGHT; 
      holder.txtMessage.setLayoutParams(layoutParams); 
      holder.lnr_image.setLayoutParams(layoutParams); 
     } else { 
      holder.contentWithBG.setBackgroundResource(android.R.color.transparent); 
     } 
    } else { 
     LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) holder.contentWithBG.getLayoutParams(); 
     layoutParams.gravity = Gravity.LEFT; 
     holder.contentWithBG.setLayoutParams(layoutParams); 

     RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) holder.content.getLayoutParams(); 
     lp.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, 0); 
     lp.addRule(RelativeLayout.ALIGN_PARENT_LEFT); 
     holder.content.setLayoutParams(lp); 

     layoutParams = (LinearLayout.LayoutParams) holder.txtInfo.getLayoutParams(); 
     layoutParams.gravity = Gravity.RIGHT; 
     holder.txtInfo.setLayoutParams(layoutParams); 

     if (holder.txtMessage != null) { 
      holder.contentWithBG.setBackgroundResource(R.drawable.bubblegraycopy); 
      layoutParams = (LinearLayout.LayoutParams) holder.txtMessage.getLayoutParams(); 
      layoutParams.gravity = Gravity.RIGHT; 
      holder.txtMessage.setLayoutParams(layoutParams); 
     } else { 
      holder.contentWithBG.setBackgroundResource(android.R.color.transparent); 
     } 
    } 
}