Android gridview项目更改

Question

我想在设置适配器后更改GridView中的onCreateView()项目背景。我试过这种方式：

final int numVisibleChildren = gv_categories.getAdapter().getCount();       

    for ( int i = 0; i < numVisibleChildren; i++ ) {
        int positionOfView = i + 1;

        try {   
            if (positionOfView == Integer.valueOf(m_transactionItem.getIcon())) { 
                View view = gv_categories.getChildAt(i);
                int nColor = Color.parseColor(m_transactionItem.getcolor());
                if(view != null) {
                    view.setBackgroundColor(nColor);
                }
            }
        } catch(Exception e) {
            Log.e("GridviewItemErr", e.toString());
        }
    }

但view总是null。这是我的自定义适配器，包含ImageView和TextView：

public class CategoryAdapter extends BaseAdapter {
private Context mContext;
int id = 0;
private LayoutInflater inflater;
ViewHolder holder;

public static class ViewHolder {
    private TextView text;
    private ImageView icon;
    private int mId;

    public int getId() {
        return mId;
    }
    public void setId(int id) {
        mId = id;
    }


}

public CategoryAdapter(Context c) {
    mContext = c;
    inflater = (LayoutInflater) c.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

public int getCount() {
    return mAllIcons.length;
}

public Object getItem(int position) {
    return 0;
}

public long getItemId(int position) {
    return 0;
}

// create a new ImageView for each item referenced by the Adapter
@Override
public View getView(int position, View convertView, ViewGroup parent) {

    if (convertView == null) {
        id++;
        holder = new ViewHolder();
        convertView = inflater.inflate(R.layout.categories_grid_item, null);
        holder.icon = (ImageView) convertView.findViewById(R.id.ivGrid_Item_Category);
        //holder.icon.setId(id);
        holder.icon.setScaleType(ImageView.ScaleType.FIT_CENTER);
        holder.text = (TextView) convertView.findViewById(R.id.tvGrid_Item_Category);
        //holder.text.setId(id);
        holder.setId(id);
    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    holder.icon.setImageResource(mAllIcons[position]);
    holder.text.setText(mCategNames[position]);


    convertView.setTag(holder);
    return convertView;
}

private Integer[] mAllIcons = {
        R.drawable.icon_1_prijevoz_neselktirane,
        R.drawable.icon_2_putovanje_neselktirane,
        R.drawable.icon_3_hoteli_neselektirane,
        R.drawable.icon_4_odrzavanje_neselktirane,
        R.drawable.icon_5_zabava_neselktirane,
        R.drawable.icon_6_kucne_potrepstine_neselektirane,
        R.drawable.icon_7_odjeca_neselektirane,
        R.drawable.icon_8_trgovina_neselektirane,
        R.drawable.icon_9_rezije_neselktirane,
        R.drawable.icon_10_restorani_neselktirane,
        R.drawable.icon_11_slobodno_vrijeme_neselktirane,
        R.drawable.icon_12_luksuz_neselktirane,
        R.drawable.icon_13_odmor_i_rekreacija_neselktirane,
        R.drawable.icon_14_ostalo_neselektirane,
        R.drawable.icon_15_prihod_neselektirane,
        R.drawable.icon_16_stalni_prihodi_neselektirane,
        R.drawable.icon_17_default_neselektirane
};

private String[] mCategNames = {
        "Prijevoz", "Putovanje",
        "Hoteli", "Održavanje",
        "Zabava", "Kućne potrepštine",
        "Odjeća", "Trgovina",
        "Režije", "Restorani",
        "Slobodno vrijeme", "Luksuz",
        "Odmor i rekreacija",
        "Ostalo", "Prihod",
        "Stalni prihod", "Default",
};
}

我尝试了很多其他方法来做到这一点，但我无法弄清楚如何获得“可见”的GridView项目。

注意：

创建片段时需要更改背景，而不是onItemClickedListener或onScrollListener或类似...

Answer 1

我认为你的问题源于你在ImageAdapter创建它们之前尝试引用网格的视图，如果你真的要在onCreateView()时设置背景颜色而不是在调用getView()时，我会建议您使用getViewTreeObserver().addOnGlobalLayoutListener，以确保在调用getChildAt（i）之前Gridview已正确膨胀，您的代码看起来像这样：

gv_categories.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {
        //At this point the layout is complete and the 
        //dimensions of myView and any child views are known.
        final int numVisibleChildren = gv_categories.getAdapter().getCount();       
        for ( int i = 0; i < numVisibleChildren; i++ ) {
            int positionOfView = i + 1;
            try {   
                if (positionOfView == Integer.valueOf(m_transactionItem.getIcon())) { 
                View view = gv_categories.getChildAt(i);
                int nColor = Color.parseColor(m_transactionItem.getcolor());
                    if(view != null) {
                        view.setBackgroundColor(nColor);
                    }
                }
            } catch(Exception e) {
            Log.e("GridviewItemErr", e.toString());
        }
    }
});

Answer 2

根据我的理解，使用'Adapter'，我认为你不需要在创建时直接触摸视图。只需更改适配器的数据集，以及系统调用时

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

您可以创建新视图或重用转换后的视图。

另一种情况是数据在运行时发生变化，请确保更新发生在工作线程中。并致电：

public void notifyDataSetChanged()

通知UI线程相应地更改UI。

Answer 3

您应该根据位置从ListAdapter方法内部更改getView()项目。由于Views被回收，如果位置与您想要更改的位置不匹配，请不要忘记还原更改（例如将背景重置为默认值）。

AdapterViews如GridView根据布局和滚动位置从他们的Adapters动态加载他们的项目，所以他们没有在最初的View人口中填充。