Question

显示功能位于Main_activity类下。它显示给定目录下的所有文件。它来自

protected void OnCreate(Bundle SavedInstanceState)
{
 ..//other code
display(path)
}

public  void display(String path)
{
   try {
    File folderX = new File(path);
    ActionBar actionBar = getSupportActionBar();
    actionBar.setTitle(folderX.getParentFile().getName() + " / " + folderX.getName());

    final File[] folderXCHILD = folderX.listFiles();
    Arrays.sort(folderXCHILD, new FileComparator());
    GridView gridView = (GridView)findViewById(R.id.gridView);
    gridAdapter = new GridAdapter(this, folderXCHILD,isShow);
    gridView.setAdapter(gridAdapter);

}
catch (Exception e)
{
    Toast.makeText(this, "Cannot display the Content.", Toast.LENGTH_SHORT).show();
}

 }

现在，我有另一个名为GridAdapter的类，它在网格中显示内容。 GridAdapter类本身不是Activity。

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

    View rowView;

    if (convertView == null) {

        rowView = inflater.inflate(R.layout.gridout, parent, false);

    } else {
        rowView = convertView;
    }
    holder.tv = (TextView) rowView.findViewById(R.id.textView1);
    holder.img = (ImageView) rowView.findViewById(R.id.imageView1);
    holder.chk = (CheckBox) rowView.findViewById(R.id.checkBox);

    if (isShow) {
        holder.chk.setVisibility(View.VISIBLE);
    } else {
        holder.chk.setVisibility(View.GONE);
    }
    final File f = data[position];

    if (f.isDirectory())
    {
      holder.img.setImageResource(R.mipmap.folderpic);
        holder.tv.setText(f.getName());
        holder.chk.setChecked(checkBoxState[position]);
    }
    else
    {
        ImageLoader.getInstance().displayImage("file://" + f.getPath(), holder.img);

        holder.tv.setBackgroundResource(R.color.colorSecond);
        holder.tv.setText("");
        holder.chk.setChecked(checkBoxState[position]);
    }



rowView.setOnClickListener(new View.OnClickListener() {
                 @Override
                 public void onClick(View v) {
                       if(f.isDirectory())
                              {
                     // I want to call the display(f.getPath()) method of MainActivity.
                 }
             });

    return rowView;
}

问题是我想从GridAdapter中的onClick（）方法调用display（）方法。我该怎么办？

Answer 1

你必须选择： 1.将上下文转换为活动 2.将上下文强制转换为接口

看看这一行：

gridAdapter = new GridAdapter(this, folderXCHILD,isShow);

您正在向适配器发送上下文。因此，在适配器内部保存上下文的引用并使用它

((YourActivityOrInterface)context).YourFunctionOnActivity()

如何从Helper类调用Main_Activity类中的方法？

1 个答案: