Question

我正在使用带有baseadapter的listview，并且在列表视图滚动时它会崩溃。

我getView类的BaseAdapter方法

    @Override
public View getView(final int arg0, View arg1, ViewGroup arg2) {
    // TODO Auto-generated method stub

    LayoutInflater inflater = activity.getLayoutInflater();
    ViewHolder holder=null;

    if(arg1 == null){

        //Login category
        if(categoryList.get(arg0).getType()==1){
            arg1 = inflater.inflate(R.layout.switch_profile_header, null);
            holder=new ViewHolder();
            holder.layout=(RelativeLayout)arg1.findViewById(R.id.switch_profile_header_view);
            holder.categoryName =(TextView)arg1.findViewById(R.id.categoryName);
            holder.isLogin=categoryList.get(arg0).getIsLogin();
            arg1.setTag(holder);
        }
        //Other category
        else if(categoryList.get(arg0).getType()==0){
            arg1 = inflater.inflate(R.layout.switch_profile_listrow, null);
            holder=new ViewHolder();
            holder.layout=(RelativeLayout)arg1.findViewById(R.id.switch_profile_listrow_view);
            holder.categoryName =(TextView)arg1.findViewById(R.id.categoryName);
            holder.isLogin=categoryList.get(arg0).getIsLogin();
            holder.isDelete=(ImageView)arg1.findViewById(R.id.categoryDelete);
            holder.login=(ImageView)arg1.findViewById(R.id.categoryLogin);
            arg1.setTag(holder);
        }


    }else {
        holder = (ViewHolder) arg1.getTag();
    }
    //Login category
    if(categoryList.get(arg0).getType()==1){
        holder.categoryName.setText(Html.fromHtml(categoryList.get(arg0).getCategoryName()));
        holder.layout.setBackgroundColor(Color.parseColor("#efefef"));
    }
    //Login category
    else if(categoryList.get(arg0).getType()==0){
        if(flag==false){
            holder.isDelete.setVisibility(View.INVISIBLE);
        }else{
            holder.isDelete.setVisibility(View.VISIBLE);
        }

        if(categoryList.get(arg0).getIsLogin().equalsIgnoreCase("1")){
            holder.isDelete.setVisibility(View.INVISIBLE);
            holder.login.setVisibility(View.INVISIBLE);
        }else if(flag) {
            holder.isDelete.setVisibility(View.VISIBLE);
            holder.login.setVisibility(View.VISIBLE);
        }

        holder.categoryName.setText(Html.fromHtml(categoryList.get(arg0).getCategoryName()));
        if(categoryList.get(arg0).getIsLogin().equalsIgnoreCase("1")){
            holder.layout.setBackgroundColor(Color.parseColor("#efefef"));
        }else{
            holder.layout.setBackgroundColor(Color.parseColor("#f0f0f0"));
        }


    return arg1;
}

我的Logcat

 Process: com.Tiger.Tiger, PID: 14059
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setVisibility(int)' on a null object reference
        at com.TenderTiger.Adapter.SwitchProfileAdapter.getView(SwitchProfileAdapter.java:117)
        at android.widget.HeaderViewListAdapter.getView(HeaderViewListAdapter.java:220)
        at android.widget.AbsListView.obtainView(AbsListView.java:2344)
        at android.widget.ListView.makeAndAddView(ListView.java:1864)
        at android.widget.ListView.fillDown(ListView.java:698)
        at android.widget.ListView.correctTooLow(ListView.java:1474)

Answer 1

因为我必须在getView方法中夸大两种不同的布局。
正如Blackbelt所建议的那样，我必须在getViewTypeCount类中实现BaseAdapter方法。
我做了上面的工作并且工作正常，但是当我滚动它会强制关闭。

我们必须实施

getViewTypeCount以及getItemViewType将其付诸实践

1）getViewTypeCount方法返回布局总数
2）getItemViewType方法返回哪个行以适当的条件膨胀。

所以最后我的代码看起来像这个

private static final int TYPE_HEADER = 0;
private static final int TYPE_ROW = 1;

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

@Override
public int getItemViewType(int position) {
    return (categoryList.get(position).getType()==1)?TYPE_HEADER :TYPE_ROW;
}

最后是我的getView方法

    @Override
public View getView(final int position, View convertView, ViewGroup arg2) {
    // TODO Auto-generated method stub

    LayoutInflater inflater = activity.getLayoutInflater();
    ViewHolder holder=null;
    if(convertView == null) {
        if (getItemViewType(position) == TYPE_HEADER) { // Header
            convertView = inflater.inflate(R.layout.switch_profile_header, null);
            holder = new ViewHolder();
            holder.layout = (RelativeLayout) convertView.findViewById(R.id.switch_profile_header_view);
            holder.categoryName = (TextView) convertView.findViewById(R.id.categoryName);
            holder.isLogin = categoryList.get(position).getIsLogin();
            convertView.setTag(holder);

        } else {
            //row
            convertView = inflater.inflate(R.layout.switch_profile_listrow, null);
            holder = new ViewHolder();
            holder.layout = (RelativeLayout) convertView.findViewById(R.id.switch_profile_listrow_view);
            holder.categoryName = (TextView) convertView.findViewById(R.id.categoryName);
            holder.isLogin = categoryList.get(position).getIsLogin();
            holder.isDelete = (ImageView) convertView.findViewById(R.id.categoryDelete);
            holder.login = (ImageView) convertView.findViewById(R.id.categoryLogin);
            convertView.setTag(holder);
        }
    }else {
        holder = (ViewHolder) convertView.getTag();
    }

    //Header
    if(getItemViewType(position) == TYPE_HEADER){

    }
    //row
    else if(getItemViewType(position) == TYPE_ROW){

    }

    return convertView;
}

使用ViewHolder的Baseadapter，在滚动时崩溃

1 个答案: