提取适配器的GridView的ArrayList值 [英] Extract ArrayList values from Adapter to GridView

问题描述

我可以找到大量的关于如何使用ArrayList中的BaseAdapter类填充GridView的例子，但我有困难
传递正确的价值观。这是工作的罚款，而我只是使用光标的位置，但我需要使用
现在ArrayList的。据我知道解决的办法在于正确地填充的getItem和getItemID。哪里的错误 -
可有人帮忙吗？下面有关code：

  @覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.activity_main）;allImages = Images.Media.EXTERNAL_CONTENT_URI;
ArrayList的＆LT;串GT; imageCollection =新的ArrayList＆LT;串GT;（）;的String [] =投影{
      MediaStore.Images.Media._ID，
      MediaStore.Images.Media.DATA
};
getCursor = getContentResolver（）查询。（
      allImages，
      投影，
      空值，
      空值，
      空值
）;
参数：columnIndex = getCursor.getColumnIndexOrThrow（投影[0]）; // -  身份证号。
arrayIndex = getCursor.getColumnIndexOrThrow（投影[1]）; // -  文件路径。
imageCollection.add（将String.valueOf（参数：columnIndex））;GridView控件的GridView =（GridView控件）findViewById（R.id.gridview）;
gridView.setAdapter（新ImageAdapter（这一点，imageCollection））;
} // --- OnCreate中结束 - 公共类ImageAdapter延伸BaseAdapter {
    私人上下文的背景下;
    私人诠释colCount;
    私人的ArrayList＆LT;串GT; tempCollection;    公共ImageAdapter（上下文C，ArrayList的＆LT;串GT; anyCollection）{
        上下文= C;
        tempCollection = anyCollection;
        colCount = tempCollection.size（）;
    }
    // ---返回图像的数量---
    公众诠释的getCount（）{
        返回colCount;
    }
    // ---返回该项目---
    公共对象的getItem（INT位置）{
        返回tempCollection.get（位置）;    }
    // ---返回一个项目的ID。
    众长getItemId（INT位置）{
        返回的位置;
    }公共查看getView（INT位置，查看convertView，父母的ViewGroup）{
    ImageView的ImageView的;
    如果（convertView == NULL）{// ---如果不是回收，初始化一些属性 - 
        ImageView的=新ImageView的（上下文）;
    }其他{
        ImageView的=（ImageView的）convertView;
    }
    字符串imageID =将String.valueOf（位置）; // ---失败：始​​终为0，低于造成FileNotFound异常!!!
    imageView.setLayoutParams（新GridView.LayoutParams（85，85））;
    imageView.setScaleType（ImageView.ScaleType.CENTER_CROP）;
    imageView.setPadding（5,5,5,5）;
    imageView.setCropToPadding（真）;
    imageView.setImageURI（// ---现在，创建每个显示画面 - 
        Uri.withAppendedPath（MediaStore.Images.Media.EXTERNAL_CONTENT_URI，imageID）
    ）;
    返回ImageView的;
} // --- ImageAdapter结束分类 - 
 

解决方案

在活动中，请使用以下code用于保存ImageId到ArrayList

 如果（getCursor！= NULL）{
    而（getCursor.moveToNext（））{
      参数：columnIndex = getCursor.getColumnIndexOrThrow（投影[0]）;
      imageCollection.add（将String.valueOf（getCursor.getLong（参数：columnIndex））;
    }
 }
 

在ImageAdapter，getView方法，使用下面code得到ImageId：

 字符串imageID = tempCollection.get（位置）;
 

I can find plenty of examples of how to use ArrayList in the BaseAdapter class to fill a GridView, but I am having difficulty passing the correct values. This was working fine while I was just using the cursor positions, but I need to use an ArrayList now. As far as I know the solution lies in correctly populating the getItem and getItemID. Where is the mistake - can somebody help please? Relevant code below:

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); 

allImages = Images.Media.EXTERNAL_CONTENT_URI;
ArrayList<String> imageCollection = new ArrayList<String>();

String[] projection = {
      MediaStore.Images.Media._ID,
      MediaStore.Images.Media.DATA
};
getCursor = getContentResolver().query(
      allImages,
      projection,
      null,
      null,
      null
);
columnIndex = getCursor.getColumnIndexOrThrow(projection[0]);  //-- ID number.
arrayIndex  = getCursor.getColumnIndexOrThrow(projection[1]);  //-- Filepath.
imageCollection.add(String.valueOf(columnIndex));

GridView gridView = (GridView) findViewById(R.id.gridview);
gridView.setAdapter(new ImageAdapter(this, imageCollection));
}  //---End of OnCreate --

public class ImageAdapter extends BaseAdapter {
    private Context context;
    private int colCount;
    private ArrayList<String> tempCollection;

    public ImageAdapter(Context c, ArrayList<String> anyCollection) {
        context = c;
        tempCollection = anyCollection;
        colCount = tempCollection.size();
    }
    //---Returns the number of images---
    public int getCount() {
        return colCount;
    }
    //---Returns the item---
    public Object getItem(int position) {
        return tempCollection.get(position);

    }
    //---Returns the ID of one item. 
    public long getItemId(int position) {
        return position;
    } 

public View getView(int position, View convertView, ViewGroup parent) {
    ImageView imageView;
    if (convertView == null) {  //---If it's not recycled, initialize some attributes --
        imageView = new ImageView(context);
    } else {
        imageView = (ImageView) convertView;
    }
    String imageID  = String.valueOf(position);  //--- FAILS: always 0, causing FileNotFound Exception below.!!!
    imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
    imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
    imageView.setPadding(5,5,5,5);
    imageView.setCropToPadding(true);
    imageView.setImageURI(                //--- Now create each individual display image --
        Uri.withAppendedPath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, imageID)
    );
    return imageView;
} //---End of ImageAdapter class--

解决方案

In activity, use below code for saving the ImageId to the ArrayList.

if (getCursor != null) {
    while (getCursor.moveToNext()) {
      columnIndex = getCursor.getColumnIndexOrThrow(projection[0]);  
      imageCollection.add(String.valueOf(getCursor.getLong(columnIndex));
    }
 }

In ImageAdapter, getView method, get the ImageId by using below code:

String imageID  = tempCollection.get(position);

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