Question

我写了一个活动，使用ImageLoaderConfiguration库将图像下载到Bitmap对象中。这工作正常。

我的下一个阶段是创建5个GalleryItem对象并将Bitmap放入这些对象中。

最后，我创建了一个GalleryItemAdapter对象，它扩展了ArrayAdapter。

问题是在函数getView中，getItem(position)返回null。

以下是代码：

mainActivity：

package com.example.downloadimages;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;

import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
import com.nostra13.universalimageloader.core.listener.SimpleImageLoadingListener;

import android.graphics.Bitmap;
import android.widget.ArrayAdapter;
import android.widget.GridView;
import android.widget.ImageView;

public class MainActivity extends ActionBarActivity {

    public String mUrl;
    public Byte [] mImageBytes;
    GalleryItem [] mGalleryItem;
    Bitmap mBitmap;
    public GridView mGridView;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
                setContentView(R.layout.image_view_in_layout);
                mGridView = (GridView) findViewById(R.id.gridView);
                mUrl = "http://www.royalcanin.in/var/royalcanin/storage/images/breeds/cat-breeds/norwegian-forest-cat/19311843-15-eng-GB/norwegian-forest-cat_cat_breed_cat_picture.jpg";

                ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this) .build();
                ImageLoader.getInstance().init(config);
                ImageLoader.getInstance().loadImage(mUrl, new SimpleImageLoadingListener(){
                    @Override
                    public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
                        mBitmap = loadedImage;
                        mGalleryItem = new GalleryItem[5];
                        for(GalleryItem gi : mGalleryItem)
                        {
                            gi = new GalleryItem();
                            gi.setBitmap(mBitmap);
                        }
                        setupAdapter();
                    }
                });
        }

        void setupAdapter()
        {
            if ( mGridView == null) return;
            mGridView.setAdapter(new GalleryItemAdapter(mGalleryItem)); 
        }

        private class GalleryItemAdapter extends ArrayAdapter<GalleryItem>
        {
            public GalleryItemAdapter(GalleryItem[] mGalleryItem) 
            {
                super(getApplicationContext(), 0, mGalleryItem);
            }

            @Override
            public View getView(int position, View convertView, ViewGroup parent) 
            {
                convertView = (ImageView)findViewById(R.id.imageView1);
                GalleryItem item = getItem(position);
                ((ImageView) convertView).setImageBitmap(item.getBitmap());
                return convertView;
            }
        }
}

类GalleryItem：

public class GalleryItem {

    Bitmap bitmap;

    public Bitmap getBitmap() {
        return bitmap;
    }

    public void setBitmap(Bitmap bitmap) {
        this.bitmap = bitmap;
    }
}

image_view_in_layout：

<?xml version="1.0" encoding="utf-8"?>
  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

     <GridView 
        android:id="@+id/gridView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:columnWidth="120dp"
        android:numColumns="auto_fit"
        android:stretchMode="columnWidth" >

    </GridView>
  </LinearLayout

谢谢！

Answer 1

您的适配器代码错误。您正在尝试将位图设置为活动xml中的ImageView。您需要在适配器中创建新的ImageView并将其返回。你可以在这里查看https://github.com/codepath/android_guides/wiki/Using-an-ArrayAdapter-with-ListView

android - get中的get item（position）返回null

1 个答案: