ContextMenu 无法使用自定义适配器从 ListView 中删除行

Question

问题是：我的 ContextMenu 无法使用自定义适配器从 ListView 中删除一行，并且 应用程序因错误而崩溃：UnsupportedOperationException，请参阅 Logcat 输出。

我已经完成了 Google 搜索并搜索了 stackoverflow。我找到的信息都没有解决这个问题。

我的问题是：我的代码有什么问题？ 请提供正确的代码来解决这个问题。

Java 代码：

        public class TestActivity extends ListActivity {

        private String itemNameArray[];
        private String dateArray[];

        private ListView listview;
        CustomListViewAdapter customListViewAdapter;

                        @Override
                        public void onCreate(Bundle savedInstanceState) {
                            super.onCreate(savedInstanceState);

                            setContentView(R.layout.activity_test);

                            registerForContextMenu(getListView());

                            root = Environment.getExternalStorageDirectory() + File.separator + "/ListTestFiles";
                            getDir(root);

            listview = getListView();

            name=itemNameArray;
            lastmod=dateArray;

            customListViewAdapter = new CustomListViewAdapter(this, name, lastmod);

            listview.setAdapter(customListViewAdapter);

      } // End of onCreate code.


        class CustomListViewAdapter extends ArrayAdapter<String> {
            Context context;
            String[] nameArray;
            String[] modifiedArray;

            CustomListViewAdapter(Context c, String[] name, String[] lastmod)
            {
                super(c, R.layout.layout_item_view, R.id.rowtext, name);
                this.context = c;
                this.nameArray = name;
                this.modifiedArray = lastmod;
            }

            public View getView(int position, View convertView, ViewGroup parent)
            {
                LayoutInflater inflater=(LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                View row = inflater.inflate(R.layout.layout_item_view, parent, false);

                TextView myName;
                TextView myLastMod;

                myName=(TextView) row.findViewById(R.id.rowtext);
                myName.setText(nameArray[position]);

                myLastMod=(TextView) row.findViewById(R.id.textView6);
                myLastMod.setText(modifiedArray[position]);

                return row;
            }
        }


         @Override
         public void onCreateContextMenu(ContextMenu menu, View v,
                                         ContextMenu.ContextMenuInfo menuInfo) {
             super.onCreateContextMenu(menu, v, menuInfo);
                 MenuInflater inflater = getMenuInflater();
                 inflater.inflate(R.menu.context_menu, menu);
         }

        @Override
        public boolean onContextItemSelected(MenuItem itemMenu) {

            final AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo)itemMenu.getMenuInfo();

            switch (itemMenu.getItemId()) {
                case R.id.context_menu_rename:
                    Toast.makeText(this, "Rename", Toast.LENGTH_SHORT).show();
                    return true;
                case R.id.context_menu_delete:
                    // NOTE TESTING the line of code below caused a runtime error: java.lang.UnsupportedOperationException
                    customListViewAdapter.remove(customListViewAdapter.getItem(info.position));
                    customListViewAdapter.notifyDataSetChanged();

                    Toast.makeText(getApplicationContext(), "position = " + info.position, Toast.LENGTH_SHORT).show();
                    Toast.makeText(this, "Delete", Toast.LENGTH_SHORT).show();

                return true;

                return super.onContextItemSelected(itemMenu);
        }
    }
}

Logcat 输出：

11-13 10:45:21.229  21432-21432/com.testing.listapp D/AndroidRuntime﹕ Shutting down VM
    --------- beginning of crash
11-13 10:45:21.246  21432-21432/com.testing.listapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.testing.listapp, PID: 21432
    java.lang.UnsupportedOperationException
            at java.util.AbstractList.remove(AbstractList.java:638)
            at java.util.AbstractList$SimpleListIterator.remove(AbstractList.java:75)
            at java.util.AbstractCollection.remove(AbstractCollection.java:229)
            at android.widget.ArrayAdapter.remove(ArrayAdapter.java:244)
            at com.testing.listapp.TestActivity.onContextItemSelected(TestActivity.java:5468)
            at android.app.Activity.onMenuItemSelected(Activity.java:2905)
            at com.android.internal.policy.impl.PhoneWindow$DialogMenuCallback.onMenuItemSelected(PhoneWindow.java:4701)
            at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:761)
            at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:152)
            at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:904)
            at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:894)
            at com.android.internal.view.menu.MenuDialogHelper.onClick(MenuDialogHelper.java:167)
            at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:1082)
            at android.widget.AdapterView.performItemClick(AdapterView.java:305)
            at android.widget.AbsListView.performItemClick(AbsListView.java:1146)
            at android.widget.AbsListView$PerformClick.run(AbsListView.java:3053)
            at android.widget.AbsListView$3.run(AbsListView.java:3860)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5254)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

Answer 1

我修改了你的工作：

public class TestActivity extends ListActivity { 
    private ArrayList<String> itemNameArray;
     private ArrayList<String> dateArray;
     private ListView listview;
     CustomListViewAdapter customListViewAdapter; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState);
     setContentView(R.layout.activity_test);
     registerForContextMenu(getListView());
 String root = Environment.getExternalStorageDirectory() + File.separator + "/ListTestFiles";
     getDir(root);

     listview = getListView();

     CustomListViewAdapter = new CustomListViewAdapter(this, itemNameArray, dateArray);
     listview.setAdapter(customListViewAdapter);
     }
     // End of onCreate code. class

     CustomListViewAdapter extends ArrayAdapter<String> { 
    ArrayList<String> nameArray;
     ArrayList<String> modifiedArray; CustomListViewAdapter(Context c, ArrayList<String> name, ArrayList<String> lastmod) {
     super(c, 0, name); 
     this.nameArray = name;
     this.modifiedArray = lastmod;
     } 
    public View getView(int position, View convertView, ViewGroup parent) { 
    LayoutInflater inflater=LayoutInflater.from(parent.get context());
     convertView = inflater.inflate(R.layout.layout_item_view, parent, false); 
    TextView myName; 
    TextView myLastMod;
     myName=(TextView) row.findViewById(R.id.rowtext);
     myName.setText(nameArray.get(position));
     myLastMod=(TextView) row.findViewById(R.id.textView6);
     myLastMod.setText(modifiedArray.get(position));
     return convertView;
     }
     }

     @Override
     public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) { 
    super.onCreateContextMenu(menu, v, menuInfo); 
    getMenuInflater().inflate(R.menu.context_menu, menu); 
    }

     @Override 
    public boolean onContextItemSelected(MenuItem itemMenu) {

    switch (itemMenu.getItemId()) { 
    case R.id.context_menu_rename:
     Toast.makeText(this, "Rename", Toast.LENGTH_SHORT).show();
     break; 
    case R.id.context_menu_delete: itemNameArray.remove(listView.getSelectedItemPosition());
    dateArray.remove(listView.getSelectedItemPosition()); customListViewAdapter.notifyDataSetChanged(); 
     break; 
    }
    return true;
     }
     }

Answer 2

只需在该特定位置从 nameArray 和 modifiedArray 中删除项目，然后通知 adapter 数据集更改。

我明白了。一个大错误是在需要动态大小数组的地方使用固定大小的数组。

改变你的

String nameArray[];
String modifiedArray[];

到

ArrayList<String> nameArray;
 ArrayList<String> modifiedArray;