Question

我的代码这是一个适配器，我希望在列表视图中左右动态对齐我的布局......空指针异常将在relativeParams.leftMargin=80;

爪哇：

public View getView(int position, View view, ViewGroup parent)
    {
        ViewHolder viewHolder;
        ChatItem chatItem = getItem(position);
        viewAligned = view;
        if(view == null)
        {
            LayoutInflater layoutInflater = (LayoutInflater)  
            context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = layoutInflater.inflate(R.layout.cell_messages_layout, null);
            viewHolder = new ViewHolder();
            viewHolder.message = (TextView) view.findViewById(R.id.fromZoneMessage1);
            viewHolder.rl = (RelativeLayout) view.findViewById(R.id.messageLayout);
            view.setTag(viewHolder);
        }
        else
        {
            viewHolder = (ViewHolder) view.getTag();
        }

        viewHolder.message.setText(chatItem.getSenderMessage());
        if (chatItem.getAllignment() == 0)
        {
//          viewHolder.message.setGravity(Gravity.LEFT);
            viewHolder.message.setBackgroundResource(R.drawable.sent_message);
//          view.setBackgroundResource(R.drawable.sent_message);
        }
        else {
//          viewHolder.rl.setBackgroundResource(R.drawable.recieved_message);
//          view.holder.rl.set
//          viewHolder.message.setGravity(Gravity.RIGHT);
            viewHolder.message.setBackgroundResource(R.drawable.recieved_message);

            RelativeLayout.LayoutParams relativeParams = (RelativeLayout.LayoutParams) viewHolder.rl.getLayoutParams();
            relativeParams.leftMargin=80;
            viewHolder.rl.setLayoutParams(relativeParams);
//          LayoutParams lp = (LayoutParams) view.getLayoutParams();
        }
        return view;
    }

我的布局是....

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/messageLayout" 
   >


    <TextView 
        android:id="@+id/fromZoneMessage1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#000000"
        android:textSize="20dp"
        android:textStyle="bold"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="5dp"
        android:layout_marginBottom="5dp"
        android:layout_marginRight="10dp"
        android:padding="5dp"
        android:text="Hey Jack"
        />

</RelativeLayout>

请有人帮我把左边距放在我看来......

Answer 1

我只是将视图输入到相对布局并设置其重力...用于设置参数，意味着边缘我在主相对布局中采用了另一个虚拟相对布局并调整它。

您可以观看以下代码和相对布局

public View getView(int position, View view, ViewGroup parent)
    {
        ViewHolder viewHolder;
        ChatItem chatItem = getItem(position);
        viewAligned = view;
        if(view == null)
        {
            LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = layoutInflater.inflate(R.layout.cell_messages_layout, null);
            viewHolder = new ViewHolder();
            viewHolder.message = (TextView) view.findViewById(R.id.fromZoneMessage1);
            viewHolder.rl = (RelativeLayout) view.findViewById(R.id.messageLayout);
            view.setTag(viewHolder);
        }
        else
        {
            viewHolder = (ViewHolder) view.getTag();
        }

        viewHolder.message.setText(chatItem.getSenderMessage());
        if (chatItem.getAllignment() == 0)
        {

            viewHolder.message.setGravity(Gravity.LEFT);
            viewHolder.message.setBackgroundResource(R.drawable.recieved_message);
            ((RelativeLayout)view).setGravity(Gravity.RIGHT);
            android.widget.RelativeLayout.LayoutParams params = new LayoutParams(android.widget.RelativeLayout.LayoutParams.WRAP_CONTENT, android.widget.RelativeLayout.LayoutParams.WRAP_CONTENT);
            params.leftMargin = 50;
            viewHolder.rl.setLayoutParams(params);

                    }
        else {
            viewHolder.message.setGravity(Gravity.LEFT);
            viewHolder.message.setBackgroundResource(R.drawable.sent_message);
            ((RelativeLayout)view).setGravity(Gravity.LEFT);
            android.widget.RelativeLayout.LayoutParams params = new LayoutParams(android.widget.RelativeLayout.LayoutParams.WRAP_CONTENT, android.widget.RelativeLayout.LayoutParams.WRAP_CONTENT);
            params.rightMargin = 50;
            viewHolder.rl.setLayoutParams(params);
        }

        return view;
    }

布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
   >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/messageLayout" 
       >


    <TextView 
        android:id="@+id/fromZoneMessage1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#000000"
        android:textSize="20dp"
        android:textStyle="bold"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="5dp"
        android:layout_marginBottom="5dp"
        android:layout_marginRight="10dp"
        android:padding="5dp"
        android:text="Hey Jack"/>

</RelativeLayout>
</RelativeLayout>

Answer 2

尝试使用AbsListView.LayoutParams而不是使用RelativeLayout.LayoutParams，因为您的视图位于ListView中。

为视图设置左边距... NullPointerException即将到来

2 个答案: