Question

我正在使用 ListFragment 和自定义适配器。

我的适配器有一个textview和一个带箭头的隐藏imageview。当用户选择项目时，箭头显示并且背景颜色发生变化。但是，当用户滚动列表时，所有更改都将恢复为默认值。

我应该怎样做才能解决这些变化？

编辑：

我的Adapter类..

public class PropriedadeAdapter extends BaseAdapter {
private Context context;
private List<Propriedades> prop;

public PropriedadeAdapter(Context context, List<Propriedades> prop) {
    this.context = context;
    this.prop = prop;
}

public int getCount() {
    return prop.size();
}

public Object getItem(int position) {
    return prop.get(position);
}

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

public View getView(int position, View convertView, ViewGroup parent) {
    // Recupera o produto da posição atual
    Propriedades p = prop.get(position);

    // Layout XML
    int arquivoLayout = R.layout.lista_prop;
    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View v = inflater.inflate(arquivoLayout, null);

    // Atualiza o valor do Text para o nome do produto
    TextView textNome = (TextView) v.findViewById(R.id.nome);
    textNome.setText(p.getNome());

    return v;
}
}

my Fragment class ..

public class frag_lista extends ListFragment{

ImageView ultimoItem = null;

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
     ArrayList<Propriedades> props = new ArrayList<Propriedades>();
    for(int i = 0; i <50; i++)
    {
        Propriedades prop = new Propriedades();
        prop.setNome("FRUTA "+i);
        props.add(prop);
    }
    setListAdapter(new PropriedadeAdapter(this.getActivity(),props));
}


@Override
public void onListItemClick(ListView l, View v, int position, long id) {
    ImageView seta = (ImageView)v.findViewById(R.id.imgSeta);
    seta.setVisibility(0);
    LinearLayout linha = (LinearLayout)v.findViewById(R.id.linha);
    linha.setBackgroundColor(Color.GRAY);
    if(ultimoItem != null)
    {
        ultimoItem.setVisibility(4);
    }
    ultimoItem = seta;
}   

}

我应该怎么做才能持久化onListItemClick方法的变化????

Answer 1

根据您的评论，我认为您没有正确使用适配器。

Adapter提供ListView自动调用的方法。

每次调用getView(...)方法时，都应该将选定的索引保留在内存中并恢复View状态（从position参数中进行jusging）。

查找有关ListView和Adapter的教程。

修改

请注意，我没有测试代码，但它可能是这样的：

// TeddyBearFr: Class name typically starts with a capital letter! Frag_lista, not frag_lista public class frag_lista extends ListFragment{ ImageView ultimoItem = null; @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); ArrayList<Propriedades> props = new ArrayList<Propriedades>(); for(int i = 0; i <50; i++) { Propriedades prop = new Propriedades(); prop.setNome("FRUTA "+i); props.add(prop); } setListAdapter(new PropriedadeAdapter(this.getActivity(),props)); } @Override public void onListItemClick(ListView l, View v, int position, long id) { // TeddyBearFr: notify the adapter ( (PropriedadeAdapter) this.getListAdapter() ).onListItemClick(position); // TeddyBearFr: your last item must be managed in the getView(...) method of the Adapter //if(ultimoItem != null) //{ // ultimoItem.setVisibility(4); // TeddyBearFr: don't use integer like this, use Android constants! View.INVISIBLE //} //ultimoItem = seta; } } public class PropriedadeAdapter extends BaseAdapter { private final static String TAG = "PropriedadeAdapter"; private Context context; private List<Propriedades> prop; private Set<Integer> mSelectedItemsPosition; public PropriedadeAdapter(Context context, List<Propriedades> prop) { this.context = context; this.prop = prop; // TeddyBearFr: set to store selected indexes this.mSelectedItemsPosition = new HashSet<Integer>(); } public int getCount() { return prop.size(); } public Object getItem(int position) { return prop.get(position); } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { Log.d(TAG, "getView(position=" + position + ", convertView=" + convertView + ", parent=" + parent + ")" ); // Recupera o produto da posição atual Propriedades p = prop.get(position); // TeddyBearFr: use existing view if exist ; otherwise create a new one View v; if( convertView == null ){ // Layout XML int arquivoLayout = R.layout.lista_prop; LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); v = inflater.inflate(arquivoLayout, null); } else{ v = convertView; } // Atualiza o valor do Text para o nome do produto TextView textNome = (TextView) v.findViewById(R.id.nome); textNome.setText(p.getNome()); // TeddyBearFr: update view according its selection state ImageView seta = (ImageView)v.findViewById(R.id.imgSeta); boolean isViewSelected = this.mSelectedItemsPosition.contains(position); int visibility = ( isViewSelected ? VIEW.VISIBLE : VIEW.GONE ); seta.setVisibility(visibility); LinearLayout linha = (LinearLayout)v.findViewById(R.id.linha); linha.setBackgroundColor( isViewSelected ? Color.GRAY : Color.RED ); if( position == getCount()-1 ){ // perform special processes on the last item of the list if needed } return v; } // TeddyBearFr: callback when click public void onListItemClick(int position){ Log.d(TAG, "onListItemClick(position=" + position + ")"); // update selected index data // Note that I haven't tested if it works. Because native integer "position" will be wrapped in Integer object, there's a chance that the Set compares the references on objects instead of their value if( this.mSelectedItemsPosition.contains(position) ){ this.mSelectedItemsPosition.remove(position); } else{ this.mSelectedItemsPosition.add(position); } // ask the list to be refreshed -> you'll see that getView() will be called only for each displayed view this.notifyDataSetChanged(); } }

Answer 2

convertView有两种状态，它们是null而不是null。您的问题发生是因为eveytime yout getView（）调用新的布局inflater实例正在初始化。仅当convertView为null时初始化inflater。

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

    Propriedades p = prop.get(position); 
    int arquivoLayout = R.layout.lista_prop;

    View v;

    if (convertView==null){
        v = inflater.inflate(arquivoLayout, null);
    }
    else {
        v = convertView;
    }  

    // Atualiza o valor do Text para o nome do produto
    TextView textNome = (TextView) v.findViewById(R.id.nome);
    textNome.setText(p.getNome());

    return v;
}

另外，请记住将inflater声明为字段。

LayoutInflater inflater = null;

并在构造函数中初始化它。

public PropriedadeAdapter(Context context, List<Propriedades> prop) {
    this.context = context;
    this.prop = prop;
    inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

滚动时，Android Listview重置更改

2 个答案: