Question

我有一个与Google教程非常相似的GridView，除了我想在运行时添加ImageViews（通过子活动）。结果还可以，但View的布局搞砸了：GridView没有填充其父级的内容，我需要做些什么来正确设计它？

这里是添加孩子的代码：

public void initializeWorkbench(GridView gv, Vector<String> items) {
        Prototype.workbench.setDimension(screenWidth, divider.height()+workbenchArea.height());
        Prototype.workbench.activateWorkbench();
        // this measures the workbench correctly
        Log.d(Prototype.TAG, "workbench width: "+Prototype.workbench.getMeasuredWidth());
        // 320
        Log.d(Prototype.TAG, "workbench height: "+Prototype.workbench.getMeasuredHeight());
        // 30
        ImageAdapter imgAdapter = new ImageAdapter(this.getContext(), items);
        gv.setAdapter(imgAdapter);
        gv.measure(screenWidth, screenHeight);
        gv.requestLayout();
        gv.forceLayout();
        Log.d(Prototype.TAG, "gv width: "+gv.getMeasuredWidth());
        // 22
        Log.d(Prototype.TAG, "gv height: "+gv.getMeasuredHeight());
        // 119
        Prototype.workbench.setDimension(screenWidth, divider.height()+workbenchArea.height());
    }
}

在工作台中激活Workbench，setDimension和measure（GridView上方的LinearLayout）：

public void activateWorkbench() {
    if(this.equals(Prototype.workbench)) {
        this.setOrientation(VERTICAL);
        show = true;
        measure();
    }
}

public void setDimension(int w, int h) {
    width = w;
    height = h;
    this.setLayoutParams(new LinearLayout.LayoutParams(width, height));
    this.invalidate();
}

private void measure() {
    if (this.getOrientation() == LinearLayout.VERTICAL) {
        int h = 0;
        int w = 0;
        this.measureChildren(0, 0);
        for (int i = 0; i < this.getChildCount(); i++) {
            View v = this.getChildAt(i);
            h += v.getMeasuredHeight();
            w = (w < v.getMeasuredWidth()) ? v.getMeasuredWidth() : w;
        }
        if (this.equals(Prototype.tagarea))
            height = (h < height) ? height : h;
        if (this.equals(Prototype.tagarea))
            width = (w < width) ? width : w;
    }
    this.setMeasuredDimension(width, height);
}

ImageAdapter构造函数：

public ImageAdapter(Context c, Vector<String> items) {
    mContext = c;

    boolean mExternalStorageAvailable = false;
    boolean mExternalStorageWriteable = false;
    String state = Environment.getExternalStorageState();

    if (Environment.MEDIA_MOUNTED.equals(state)) {
        // We can read and write the media
        mExternalStorageAvailable = mExternalStorageWriteable = true;
    } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
        // We can only read the media
        mExternalStorageAvailable = true;
        mExternalStorageWriteable = false;
    } else {
        // Something else is wrong. It may be one of many other states, but
        // all we need
        // to know is we can neither read nor write
        mExternalStorageAvailable = mExternalStorageWriteable = false;
    }

    if (mExternalStorageAvailable && mExternalStorageWriteable) {
        for (String item : items) {
            File f = new File(item);
            if (f.exists()) {
                try {
                    FileInputStream fis = new FileInputStream(f);
                    Bitmap b = BitmapFactory.decodeStream(fis);
                    bitmaps.add(b);
                    files.add(f);
                } catch (FileNotFoundException e) {
                    Log.e(Prototype.TAG, "", e);
                }
            }
        }
    }
}

xml布局：

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

                android:paddingLeft="0px"
                android:paddingTop="0px"
                android:paddingRight="0px">

    <com.unimelb.pt3.ui.TransparentPanel
            android:id="@+id/workbench" 
            android:layout_width="fill_parent"
            android:layout_height="10px"
            android:paddingTop="0px"
            android:paddingLeft="0px"
            android:paddingBottom="0px"
            android:paddingRight="0px">

        <GridView xmlns:android="http://schemas.android.com/apk/res/android" 
            android:id="@+id/gridview"
            android:layout_width="fill_parent" 
            android:layout_height="fill_parent"
            android:columnWidth="90dp"
            android:numColumns="auto_fit"
            android:verticalSpacing="10dp"
            android:horizontalSpacing="10dp"
            android:stretchMode="columnWidth"
            android:gravity="center" />

    </com.unimelb.pt3.ui.TransparentPanel>

</LinearLayout>

Answer 1

GridView有一个invalidateViews（）方法。

当你调用这个方法时：“所有要重建和重绘的视图。” http://developer.android.com/reference/android/widget/GridView.html

我认为这就是你所需要的：）

Answer 2

您必须首先告诉适配器通知数据已更改并再次将适配器设置为网格

adapter.notifyDataChanged();
grid.setAdapter(adapter);

Answer 3

这可能会有所帮助。在对项目执行删除后刷新书籍图像缩略图的网格视图。使用adapter.notifyDataChanged（）;如上所述对我不起作用，因为它在我的适配器中被调用。

//this is a call that retrieves cached data.
//your constructor can be designed and used without it.
final Object data = getLastNonConfigurationInstance();

我基本上只需重新加载适配器并将其绑定到同一视图。

//reload the adapter
adapter = new BooksAdapter(MyBooks.this, MyBooks.this, data, show_collection );
grid.invalidateViews();
grid.setAdapter(adapter);

Answer 4

@flyerz @snagnever

你们一起得到它。它应该是：

adapter.notifyDataChanged();
grid.invalidateViews();

这将标记其数据已更改的适配器，然后在调用invalidateViews（）方法后将其传播到网格。

很高兴我发现了这个问题，因为我无法弄清楚如何在渲染后将项目添加到网格中。

Answer 5

这些答案中没有一个对我有用，我不得不将它们全部混合在一起。要实际让GridView更新，您需要这样做：

 adapter.notifyDataChanged();
 grid.invalidateViews();
 grid.setAdapter(adapter);

希望这可以帮助任何无法获得其他解决方案的人。

Answer 6

您不应该致电invalidateViews和setAdapter来刷新grid view。保持grid view更新不是一个好主意，如果以这种方式更新，则会花费大量时间和内存。

如果您有机会查看getView方法，您会看到convertView只创建一次。当您致电notifyDataChanged时，它会更新此视图。而如果您致电invalidateViews，则会重新创建以前创建的视图。这不是一个好的解决方案。

致电getView时，系统会调用notifyDataChanged方法。所以你的getView方法应该类似于下面的代码。

public List list;

public class SimpleItemViewHolder extends Object
{
    public TextView textView;
    public ImageView imageView;
}

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

    View itemView = convertView;
    SimpleItemViewHolder viewHolder;

    if(convertView==null)
    {
        viewHolder = (SimpleItemViewHolder)itemView.getTag();

    }else{
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        itemView = inflater.inflate(R.layout.layout_name, null);
        TextView labelField = (TextView) itemView.findViewById(R.id.label_field);
        labelField.setText(list.get(position).Name);
        //Typeface boldFont = Typeface.createFromAsset(context.getAssets(), "fonts/Font-Bold.ttf");
        //labelField.setTypeface(boldFont);

        ImageView imageView = (ImageView) itemView.findViewById(R.id.image_view);
        //Bitmap bitmap = init your bitmap here;
        //imageView.setImageBitmap(bitmap);  

        viewHolder = new SimpleItemViewHolder();
        viewHolder.imageView = imageView;
        viewHolder.textView = labelField;
        itemView.setTag(viewHolder);

    }

    //don't create new views, instead use previous ones and update them.
    viewHolder.textView.setText(list.get(position).Name);
    //viewHolder.imageView.setImageBitmap(your_bitmap);  
    return itemView;
}

Answer 7

adapter.notifyDataChanged();

可能不起作用，因为适配器的数据是陈旧的（如果活动或片段没有被销毁，并且例如已经坐在后面的堆栈中）。

因此，如果首先刷新数据，那么它将在工作之后。

Answer 8

您将GridView放在com.unimelb.pt3.ui.TransparentPanel高10px内。

您不应该使用px，而应使用dp。
将com.unimelb.pt3.ui.TransparentPanel的{{1}}更改为android:layout_height="10px"

Answer 9

在适配器中：

class MAdapter extends BaseAdapter{
   List<Objects> mObjects;
...

 public void clearAdapter(){
        mObjects.clear();
    }

 public void addNewValues(List<Objects> mObjects){
        this.mObjects = mObjects;
    }

...

}


adapter.clearAdapter(); // clear old values
adapter.addNewValues(MObjects);
adapter.notifyDataChanged();

如何刷新GridView？

9 个答案: