Question

我已经使用TextView叠加设置了一个ImageViews网格。我的ImageAdapter代码如下：

    public View getView(int position, View convertView, ViewGroup parent) {
    ImageView imageView;
    View grid;
    LayoutInflater inflater = (LayoutInflater) mContext
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    if (convertView == null) {
        grid = new View(mContext);
        grid = inflater.inflate(R.layout.image, null);
        TextView textView = (TextView)grid.findViewById(R.id.mastery_text);

        imageView = (ImageView)grid.findViewById(R.id.mastery_image);
        grid.setLayoutParams(new GridView.LayoutParams(150, 150));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        grid.setPadding(8, 8, 8, 8);
        grid.setBackgroundResource(R.color.orange);

        imageView.setImageResource(mThumbIds[position]);            

    } else {
        grid = (View) convertView;
    }

    return grid;
}

我的ImageAdapter的相应XML布局是：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layout_practitioner" 
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ImageView 
        android:id="@+id/mastery_image"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"
    />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_gravity="bottom"
        android:background="#bbffffff"
        android:focusable="false"
        android:focusableInTouchMode="false" >

        <TextView android:id="@+id/mastery_text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="0dp"
            android:textColor="@color/black"
            android:gravity="bottom|center"
            android:textSize="12sp"
            android:textAllCaps="true"
            android:paddingBottom="0dp"
            android:text="3/3"
            />

    </LinearLayout>
</FrameLayout>

我的GridView（活动类）的XML代码：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <GridView xmlns:android="http://schemas.android.com/apk/res/android"
        android:paddingTop="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:id="@+id/gridview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:numColumns="4"
        android:verticalSpacing="10dp"
        android:horizontalSpacing="10dp"
        android:stretchMode="columnWidth"
        android:gravity="center" />

</LinearLayout>

这是我主要活动的onCreate方法：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_masteries);

    GridView gridview = (GridView) findViewById(R.id.gridview);

    ImageAdapter adapter = new ImageAdapter(this);
    gridview.setAdapter(adapter);

    gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View v,
                                int position, long id) {
            Toast.makeText(Masteries.this, "" + position,
                    Toast.LENGTH_SHORT).show();
        }
    });
}

我希望在使用图像初始化网格后，根据网格上的位置，从我的活动类中更改其中一个ImageView。我该怎么做？

我不要求更改图片以响应onItemClick。提前谢谢！

编辑：我想在我的适配器中创建一个changeImage(int position, int imageId)方法并从我的活动类中调用它。这是正确的做法吗？

Answer 1

在适配器中：

public void updateImage(int position, int resourceId)
{
    mThumbIds[position] = resourceId;
    notifyDataSetChanged();
}

在您的活动中：

mAdapter.updateImage(<position>, <image_resource_id>);

备注

您必须使适配器成为您活动的成员

主要想法是修改后备数据并通知GridView这已经改变了，是时候重新绘制了

您的getView()方法实施需要大量改进。一旦系统开始回收视图，它将导致大量错误（convertView参数进入！= null，其位置与上次使用的位置不同）

这里有一个关于getView（）应如何显示的草图：

@Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder viewHolder; LayoutInflater inflater = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE); if (convertView == null) { convertView = inflater.inflate(R.layout.image, parent, false); // next three lines would not be necessary if: // a) it is the same for every item; // b) you inflate properly (using the parent); // c) you specify this in the item's xml (R.layout.image) convertView.setLayoutParams(new GridView.LayoutParams(150, 150)); convertView.setPadding(8, 8, 8, 8); convertView.setBackgroundResource(android.R.color.holo_red_light); viewHolder = new ViewHolder(); viewHolder.mTextView = (TextView)convertView.findViewById(R.id.mastery_text); viewHolder.mImageView = (ImageView)convertView.findViewById(R.id.mastery_image); // this could also be set in xml perhaps viewHolder.mImageView.setScaleType(ImageView.ScaleType.CENTER_CROP); convertView.setTag(viewHolder); } else { viewHolder = (ViewHolder)convertView.getTag(); } // update the values every time we are being asked to update the item, // because the item might have been reused from a different position viewHolder.mImageView.setImageResource(mThumbIds[position]); //viewHolder.mTextView.setText("myText"); return convertView; } public static class ViewHolder { TextView mTextView; ImageView mImageView; }

Answer 2

您可以使用名称（请参阅here）或甚至包含序列或其他内容的整数来为每个ImageView设置唯一ID（在视图中放置的每个图像处增加）。

另一种好方法是使用setTag()和getTag()标记。这个问题有一个很好的答案：What is the main purpose of setTag() getTag() methods of View?

以编程方式更改GridView中的ImageView

2 个答案: