android - ListView 得到显示，但应用程序在滚动和单击时崩溃

Question

我有一个ListView名为 custom_ 的自定义布局listview.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="20dp"
android:padding="5dp"
android:id="@+id/file_name"
/>

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textSize="18dp"
    android:id="@+id/file_path"/>

</LinearLayout>

这是我的CustomAdapter课：

public class CustomAdapter extends BaseAdapter {

ArrayList<File> result;
Context context;

private static LayoutInflater inflater=null;
public CustomAdapter(Activity parentActivity, ArrayList<File> fileList) {
    // TODO Auto-generated constructor stub
    result=fileList;
    context=parentActivity;
   inflater = ( LayoutInflater )context.
            getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
    // TODO Auto-generated method stub
    return result.size();
}

@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return position;
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return position;
}

public class Holder
{
    TextView file_name;
    TextView file_path;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub



    if (convertView == null)
    {
        LayoutInflater mInflater =   (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = mInflater.inflate(R.layout.custom_listview, null);
    }

    Holder holder=new Holder();
    holder.file_name=(TextView) convertView.findViewById(R.id.file_name);
    holder.file_path=(TextView) convertView.findViewById(R.id.file_path);
    //holder.img=(ImageView) rowView.findViewById(R.id.imageView1);
    holder.file_name.setText(result.get(position).getName());
    holder.file_path.setText(result.get(position).getPath());

    return convertView;
    }

    }

这是我onClickListener的ListView：

 public void onItemClick(AdapterView<?> parent, View view, int position,       long id) { 

    int color = Color.TRANSPARENT;
    Drawable background = parent.getChildAt(position).getBackground();
    if (background instanceof ColorDrawable)
        color = ((ColorDrawable) background).getColor();
  if(color == Color.CYAN)
  { parent.getChildAt(position).setBackgroundColor(Color.TRANSPARENT);}
    else {
      parent.getChildAt(position).setBackgroundColor(Color.CYAN);
      TextView t;
      t = (TextView) view.findViewById(R.id.file_path);
      files_selected.addElement(t.getText().toString());

      }
      }
      }

当我单击列表顶部的任何项目时，该应用程序运行良好。但是只要我向下滚动并单击任何项​​目，应用程序就会崩溃。请帮忙。谢谢！

Answer 1

不应该；

if (convertView == null)
{
   LayoutInflater mInflater =   (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
   convertView = mInflater.inflate(R.layout.custom_listview, null);

   Holder holder=new Holder();
   holder.file_name=(TextView) convertView.findViewById(R.id.file_name);
   holder.file_path=(TextView) convertView.findViewById(R.id.file_path);
   //holder.img=(ImageView) rowView.findViewById(R.id.imageView1);
   holder.file_name.setText(result.get(position).getName());
   holder.file_path.setText(result.get(position).getPath());
}else{ 
   viewHolder = (ViewHolder) view.getTag(); 
}       
view.setTag(viewHolder);

Answer 2

你忘了别的。尝试这个。如果您没有实现 else 部分，那么在滚动您的应用程序时会折叠。

Holder holder;

    if (convertView == null)
        {
     holder=new Holder();
            LayoutInflater mInflater =   (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = mInflater.inflate(R.layout.custom_listview, null);
     holder.file_name=(TextView) convertView.findViewById(R.id.file_name);
        holder.file_path=(TextView) convertView.findViewById(R.id.file_path);
    convertView.setTag(holder);
        }else{
    holder = (Holder) convertView.getTag();
    }

编辑：如果您设置了 if 条件if (convertView == null)并忘记设置 else 部分，那么recycling（滚动）的时间它将尝试重新创建并且行之间的文本更改、崩溃等都发生了。因此，每当您在 getView 中添加 if 条件时，您必须同时添加 if 和 else。