Question

我在片段中有想要在片段ListView中显示的图像。

这就是我试过的，你能猜出我的代码出了什么问题吗？

我制作了一张可绘制图像的整数ArrayList

 ArrayList<Integer> ex1 = new ArrayList<Integer>();
    ex1.add(R.drawable.a);
    ex1.add(R.drawable.b);
    ex1.add(R.drawable.c);
    ex1.add(R.drawable.d);

并尝试将其传递给片段，就像我们传递任何String ArrayList

一样

我在这样的主要活动中声明了

public static final String Data = "list";

然后

    bundle = new Bundle();
    bundle.putIntegerArrayList(DATA, ex1);
    Fragment fragment = new ExFragment();
    fragment.setArguments(arguments);
    FragmentManager fragmentManager = getFragmentManager();
    FragmentTransaction ft = fragmentManager.beginTransaction();
    ft.replace(R.id.container, fragment);
    ft.addToBackStack("");
    ft.commit();

然后在片段类

中

private ArrayList<Integer> images = new ArrayList<>();

在片段的创建

 if (getArguments() != null) {
        images = getArguments().getIntegerArrayList(MainMenu.DATA);
    }

并在oncreateview

View rootView = inflater.inflate(R.layout.fragment_ex, container, false);
    ListView listView = (ListView) rootView.findViewById(R.id.listview);
    ArrayAdapter adapter = new ArrayAdapter(getActivity(), android.R.layout.simple_list_item_1, R.id.text1, images);
    listView.setAdapter(adapter);

但它给了我NullPointerException

java.lang.NullPointerException
         at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:395)
         at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
         at android.widget.AbsListView.obtainView(AbsListView.java:2724)
         at android.widget.ListView.makeAndAddView(ListView.java:1811)
         at android.widget.ListView.fillDown(ListView.java:697)
         at android.widget.ListView.fillFromTop(ListView.java:763)
         at android.widget.ListView.layoutChildren(ListView.java:1641)
         at android.widget.AbsListView.onLayout(AbsListView.java:2549)
         at android.view.View.layout(View.java:15762)
         at android.view.ViewGroup.layout(ViewGroup.java:4867)

如果我从Strign ArrayList更改为字符串并添加Integer

，则此代码与String ArrayList完美配合

Answer 1

Java Class CustomAdapter

import android.content.Context;
import android.content.Intent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class CustomAdapter extends BaseAdapter{

    String [] Text;
    int [] Image;
    Context context;

    private static LayoutInflater inflater=null;
    public CustomAdapter(MainActivity mainActivity, String[] TextItem, int[] mainImages) {
        Text = TextItem;
        context = mainActivity;
        Image = mainImages;
        inflater = ( LayoutInflater )context.
                getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }


    @Override
    // Get number of items in list
    public int getCount() {
        return Text.length;
    }

    @Override
    // Get position of item in list
    public Object getItem(int position) {
        return position;
    }

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

    public class Holder
    {
        TextView tv;
        ImageView img;
    }

    @Override
    public View getView(final int position, View convertView, final ViewGroup parent) {
        Holder holder=new Holder();
        View rowView;

        rowView = inflater.inflate(R.layout.YOURCUSTOMXML, null);

        /** Get relevant view
         * Set image/text resource, based on list name, based on list position
         */
        holder.img=(ImageView) rowView.findViewById(R.id.IMAGEIDINCUSTOMXML);
        holder.img.setImageResource(Image[position]);

        holder.tv=(TextView) rowView.findViewById(R.id.TEXTIDINCUSTOMXML);
        holder.tv.setText(Text[position]);

        return rowView;
    }

}

此类允许您使用自定义XML布局创建自己的ListAdapter 将适配器加载到android.R.layout.simple_list_item_1时，可以在片段中调用它而不是ListView。

如何从drawable创建imges的ArrayList并在片段ListView中显示它？

1 个答案:

Java Class CustomAdapter