我创建了一个imageviewer应用。它的工作正常但是当我选择一个gridview项来删除它时，它就会停止工作。选择项目时，会出现删除按钮。单击删除按钮时，会出现一个警告对话框，要求确认。我希望在按下YES按钮后删除该文件。但它不会发生。相反，它会抛出 indexoutofbounds 异常。如何成功删除所选文件？
PhotosActivity.java
import static com.example.dell_1.myapp3.ImageViewer.ImageGallery.al_images;
public class PhotosActivity extends AppCompatActivity {
int int_position;
private GridView gridView;
GridViewAdapter adapter;
ArrayList<Model_images> al_menu = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_image_gallery);
final ImageButton button1 = (ImageButton) findViewById(R.id.button1);
final ImageButton button2 = (ImageButton) findViewById(R.id.button2);
final ImageButton button3 = (ImageButton) findViewById(R.id.button3);
final ImageButton button4 = (ImageButton) findViewById(R.id.button4);
final ImageButton button5 = (ImageButton) findViewById(R.id.button5);
button1.setVisibility(View.GONE);
button2.setVisibility(View.GONE);
button3.setVisibility(View.GONE);
button4.setVisibility(View.GONE);
button5.setVisibility(View.GONE);
gridView = (GridView) findViewById(android.R.id.list);
int_position = getIntent().getIntExtra("value", 0);
adapter = new GridViewAdapter(this, al_images, int_position);
gridView.setAdapter(adapter);
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String abc = "file://" + al_images.get(int_position).getAl_imagepath().get(position);
Intent i = new Intent(getApplicationContext(), FullImageActivity.class);
i.putExtra("id", position);
i.putExtra("folderPosition", int_position);
i.putExtra("abc", abc);
startActivity(i);
}
});
gridView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, final int position, long id) {
for (int j = 0; j < parent.getChildCount(); j++)
parent.getChildAt(j).setBackgroundColor(Color.TRANSPARENT);
// change the background color of the selected element
view.setBackgroundColor(Color.LTGRAY);
button1.setVisibility(View.VISIBLE);
button2.setVisibility(View.VISIBLE);
button3.setVisibility(View.VISIBLE);
button4.setVisibility(View.VISIBLE);
button5.setVisibility(View.VISIBLE);
button3.setOnClickListener(
new View.OnClickListener() {
public void onClick(View view) {
AlertDialog.Builder builder1 = new AlertDialog.Builder(PhotosActivity.this);
builder1.setMessage("Are you sure you want to delete it ?");
builder1.setCancelable(true);
builder1.setPositiveButton(
"Yes",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
File file = new File( al_menu.get(int_position).getAl_imagepath().get(position));
file.delete();
al_menu.remove(position);
adapter.notifyDataSetChanged();
}
});
builder1.setNegativeButton(
"No",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
AlertDialog alert11 = builder1.create();
alert11.show();
}
});
return true;
}
});
}
}
GridViewAdapter.java ：
public class GridViewAdapter extends ArrayAdapter<Model_images> {
Context context;
ViewHolder viewHolder;
ArrayList<Model_images> al_menu = new ArrayList<>();
int int_position;
public GridViewAdapter(Context context, ArrayList<Model_images> al_menu,int int_position) {
super(context, R.layout.activity_adapter__photos_folder, al_menu);
this.al_menu = al_menu;
this.context = context;
this.int_position = int_position;
}
@Override
public int getCount() {
Log.e("ADAPTER LIST SIZE", al_menu.get(int_position).getAl_imagepath().size() + "");
return al_menu.get(int_position).getAl_imagepath().size();
}
@Override
public int getItemViewType(int position) {
return position;
}
@Override
public int getViewTypeCount() {
if (al_menu.get(int_position).getAl_imagepath().size() > 0) {
return al_menu.get(int_position).getAl_imagepath().size();
} else {
return 1;
}
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
if (convertView == null) {
viewHolder = new ViewHolder();
convertView = LayoutInflater.from(getContext()).inflate(R.layout.activity_adapter__photos_folder, parent, false);
viewHolder.tv_foldern = (TextView) convertView.findViewById(R.id.tv_folder);
viewHolder.tv_foldersize = (TextView) convertView.findViewById(R.id.tv_folder2);
viewHolder.iv_image = (ImageView) convertView.findViewById(R.id.iv_image);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
viewHolder.tv_foldern.setVisibility(View.GONE);
viewHolder.tv_foldersize.setVisibility(View.GONE);
Glide.with(context).load("file://" + al_menu.get(int_position).getAl_imagepath().get(position))
.diskCacheStrategy(DiskCacheStrategy.NONE)
.skipMemoryCache(true)
.into(viewHolder.iv_image);
return convertView;
}
private static class ViewHolder {
TextView tv_foldern, tv_foldersize;
ImageView iv_image;
}
}
LOGCAT：
10-15 11:38:03.449 31844-31844/com.example.dell_1.Myapp3 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.dell_1.Myapp3, PID: 31844
java.lang.IndexOutOfBoundsException: Index: 1, Size: 0
at java.util.ArrayList.get(ArrayList.java:411)
at com.example.dell_1.myapp3.ImageViewer.PhotosActivity$2$1$1.onClick(PhotosActivity.java:87)
at android.support.v7.app.AlertController$ButtonHandler.handleMessage(AlertController.java:161)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
答案 0 :(得分：0)
什么是 al_images ??
您尚未初始化 al_images
答案 1 :(得分：0)
如果要删除Grid的项目，还应该通知网格适配器数据集中的更改。
上述行为需要在Adapter的getView（）方法中定义。在（if else）块之后填充元素。您应该为每个视图设置一个标记，以便正确识别要删除的项目。使用
ViewHolder.deleteButton.setTag(position);
在这种情况下，param将是您的删除按钮，因此在单击按钮后，您将知道单击其按钮的项目并在getView（）方法中执行以下功能。
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Gets the index of the item to delete
Integer index = (Integer) v.getTag();
// Use the above index to delete item from data set
// Delete your item here
//For e.g: notes.remove(index.intValue());
// Must call this after deletion from the data set
notifyDataSetChanged();
}
});