java - 回收 View 时抽屉导航项目消失

Question

当我第一次启动应用程序时，我以正确的方式获得了抽屉导航。当我向下滚动抽屉时，问题就出现了。元素开始消失，其中一些甚至交换了位置。我试图找出问题所在，但找不到。希望你能帮助我。

我已经使用 getItemViewType(int) 和 getViewTypeCount() 更新了我的代码，但回收 View 时问题仍然存在。

我在这里留下一些代码:

新代码

public class NavDrawerListAdapter extends BaseAdapter {

    private static final int TYPE_ITEM = 0;
    private static final int TYPE_HEADER = 1;
    private static final int TYPE_SWITCH = 2;
    private static final int TYPE_MAX_COUNT = 3;

    private Context mContext;
    private ArrayList<NavDrawerItem> navDrawerItems;
    LayoutInflater inflater;

    public NavDrawerListAdapter(Context context, ArrayList<NavDrawerItem> navDrawerItems){
        this.mContext = context;
        this.navDrawerItems = navDrawerItems;
        inflater = (LayoutInflater)
                context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        return navDrawerItems.size();
    }

    @Override
    public Object getItem(int position) {       
        return navDrawerItems.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public int getItemViewType(int position) {
        // TODO Auto-generated method stub
        //return super.getItemViewType(position);

        if((!navDrawerItems.get(position).getHeaderVisibility())
                &&(!navDrawerItems.get(position).getSwitchVisibility()))
                    return TYPE_ITEM;
        else if((navDrawerItems.get(position).getHeaderVisibility())
                &&(!navDrawerItems.get(position).getSwitchVisibility()))
                    return TYPE_HEADER;
        else if((!navDrawerItems.get(position).getHeaderVisibility())
                &&(navDrawerItems.get(position).getSwitchVisibility()))
            return TYPE_SWITCH;
        else return TYPE_ITEM;
    }

    @Override
    public int getViewTypeCount() {
        // TODO Auto-generated method stub
        //return super.getViewTypeCount();
        return TYPE_MAX_COUNT;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        Log.d("NavDrawerAdapterTest: ", "getView: " + position + " " + convertView);

        Log.d("NavDrawerAdapter: ", "0");
        ViewHolderItem viewHolder;
        int type = getItemViewType(position);
        Log.d("NavDrawerAdapter: ", "1");

        if (convertView == null) {                    

            Log.d("NavDrawerAdapter: ", "2a");

            /*LayoutInflater inflater = (LayoutInflater)
                    context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);*/
            viewHolder = new ViewHolderItem();

            switch (type) {

                case TYPE_ITEM:
                    convertView = inflater.inflate(R.layout.drawer_list_item, null);

                    viewHolder.textViewTitleItem = (TextView) convertView.findViewById(R.id.title);
                    viewHolder.imageViewIconItem = (ImageView) convertView.findViewById(R.id.icon);

                    viewHolder.imageViewIconItem.setImageResource(navDrawerItems.get(position).getIcon());        
                    viewHolder.textViewTitleItem.setText(navDrawerItems.get(position).getTitle());
                    break;

                case TYPE_HEADER:
                    convertView = inflater.inflate(R.layout.drawer_list_item_header, null);

                    viewHolder.textViewHeaderItem = (TextView) convertView.findViewById(R.id.drawerHeader);
                    viewHolder.dividerViewItem = (View) convertView.findViewById(R.id.drawerView);

                    viewHolder.textViewHeaderItem.setText(navDrawerItems.get(position).getHeader());
                    break;


                case TYPE_SWITCH:
                    convertView = inflater.inflate(R.layout.drawer_list_item_switch, null);

                    break;
            }
            convertView.setTag(viewHolder);

            } else {
                viewHolder = (ViewHolderItem)convertView.getTag();
            }

       return convertView;
    }

    static class ViewHolderItem {
        TextView textViewTitleItem;
        ImageView imageViewIconItem;
        TextView textViewHeaderItem;
        View dividerViewItem;
    }
}

原始代码

NavDrawerItem.java

public class NavDrawerItem {

    private String title;
    private int icon;
    private String header;
    private boolean isHeader;

    public NavDrawerItem(){}

    public NavDrawerItem(String title, int icon){
        this.title = title;
        this.icon = icon;
        this.isHeader = false;
    }

    public NavDrawerItem(String header) {
        this(null, 0);
        this.header = header;
        this.isHeader = true;
    }

    public String getTitle(){
        return this.title;
    }

    public int getIcon(){
        return this.icon;
    }

    public String getHeader() {
        return header;
    }

    public boolean getHeaderVisibility() {
        return isHeader;
    }

    public void setTitle(String title){
        this.title = title;
    }

    public void setIcon(int icon){
        this.icon = icon;
    }

    public void setHeader(String header) {
        this.header = header;
    }

    public void setHeaderVisibility(boolean isHeader) {
        this.isHeader = isHeader;
    }
}

NavDrawerListAdapter.java

public class NavDrawerListAdapter extends BaseAdapter {

    private Context context;
    private ArrayList<NavDrawerItem> navDrawerItems;

    public NavDrawerListAdapter(Context context, ArrayList<NavDrawerItem> navDrawerItems){
        this.context = context;
        this.navDrawerItems = navDrawerItems;
    }

    @Override
    public int getCount() {
        return navDrawerItems.size();
    }

    @Override
    public Object getItem(int position) {       
        return navDrawerItems.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        Log.d("NavDrawerAdapter: ", "0");
        ViewHolderItem viewHolder;
        Log.d("NavDrawerAdapter: ", "1");

        if (convertView == null) {                    

            Log.d("NavDrawerAdapter: ", "2a");

            LayoutInflater inflater = (LayoutInflater)
                    context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
            viewHolder = new ViewHolderItem();

            convertView = inflater.inflate(R.layout.drawer_list_item_test, null);

            viewHolder.textViewTitleItem = (TextView) convertView.findViewById(R.id.title);
            viewHolder.imageViewIconItem = (ImageView) convertView.findViewById(R.id.icon);
            viewHolder.textViewHeaderItem = (TextView) convertView.findViewById(R.id.drawerHeader);
            viewHolder.dividerViewItem = (View) convertView.findViewById(R.id.drawerView);

            convertView.setTag(viewHolder);

        } else {

            Log.d("NavDrawerAdapter: ", "2b");
            viewHolder = (ViewHolderItem) convertView.getTag();

        }

        if(navDrawerItems.get(position).getHeaderVisibility()) {


            viewHolder.textViewTitleItem.setVisibility(TextView.INVISIBLE);
            viewHolder.imageViewIconItem.setVisibility(ImageView.INVISIBLE);

            viewHolder.textViewHeaderItem.setText(navDrawerItems.get(position).getHeader());

            Log.d("NavDrawerAdapter: ", "3a");
        } else {

            viewHolder.textViewHeaderItem.setVisibility(TextView.INVISIBLE);
            viewHolder.dividerViewItem.setVisibility(View.INVISIBLE);

            viewHolder.imageViewIconItem.setImageResource(navDrawerItems.get(position).getIcon());        
            viewHolder.textViewTitleItem.setText(navDrawerItems.get(position).getTitle());

            Log.d("NavDrawerAdapter: ", "3b");
        }


        return convertView;
    }

    static class ViewHolderItem {
        TextView textViewTitleItem;
        ImageView imageViewIconItem;
        TextView textViewHeaderItem;
        View dividerViewItem;
    }
}

编辑:drawer_list_item_test.xml

<?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="48dp" 
    android:background="@drawable/list_selector">

    <ImageView
        android:id="@+id/icon"
        android:layout_width="25dp"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_marginLeft="12dp"
        android:layout_marginRight="12dp"
        android:contentDescription="@string/desc_list_item_icon"
        android:src="@drawable/ic_home"
        android:layout_centerVertical="true" />

    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_toRightOf="@id/icon"
        android:minHeight = "48dp"
        android:textSize = "16sp"
        android:textColor="@color/list_item_title"
        android:gravity="center_vertical"
        android:paddingRight="40dp"/>

    <TextView
        android:id="@+id/drawerHeader"
        android:layout_above="@id/drawerView"
        android:layout_marginLeft="12dp"
        android:layout_marginTop="12dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:textAllCaps="true"
        android:textColor="@color/list_item_title" />


    <View
        android:id="@+id/drawerView"
        android:layout_alignParentBottom="true"
        android:layout_width="match_parent"
        android:layout_height="2dp"
        android:layout_marginBottom="1dp"
        android:layout_marginTop="2dp"
        android:background="@color/list_background_pressed" />

</RelativeLayout>

Answer 1

您在使用 ListView 和适配器时遇到问题。

getView 方法中的适配器重用“旧”项目 View 。并且您必须重新设置所有内容

我的意思是:如果您使用 viewHolder.imageViewIconItem.setVisibility(ImageView.INVISIBLE); 在一种情况下，您必须使用 viewHolder.imageViewIconItem.setVisibility(ImageView.VISIBLE); > 第二种情况

这里有一些可以帮助您的代码:

   if(navDrawerItems.get(position).getHeaderVisibility()) {
        viewHolder.textViewTitleItem.setVisibility(TextView.INVISIBLE);    
        viewHolder.imageViewIconItem.setVisibility(ImageView.INVISIBLE);

        viewHolder.textViewHeaderItem.setVisibility(TextView.VISIBLE);
        viewHolder.dividerViewItem.setVisibility(View.VISIBLE);

        viewHolder.textViewHeaderItem.setText(navDrawerItems.get(position).getHeader());
        Log.d("NavDrawerAdapter: ", "3a");
    } else {

        viewHolder.textViewHeaderItem.setVisibility(TextView.INVISIBLE);
        viewHolder.dividerViewItem.setVisibility(View.INVISIBLE);

        viewHolder.textViewTitleItem.setVisibility(TextView.VISIBLE);    
        viewHolder.imageViewIconItem.setVisibility(ImageView.VISIBLE);

        viewHolder.imageViewIconItem.setImageResource(navDrawerItems.get(position).getIcon());        
        viewHolder.textViewTitleItem.setText(navDrawerItems.get(position).getTitle());

        Log.d("NavDrawerAdapter: ", "3b");
    }