Question

我需要使用“选项”菜单中的按钮从ListView中删除由复选框选择的项目。选择项目后，我试图单击“选项”菜单上的“删除”按钮，然后我的应用程序崩溃。当我使用相同的代码，并且按钮位于listview正确运行的同一xml上时，仅当我尝试使用“选项菜单项”执行相同的操作时，问题才会发生。

编辑：我正在粘贴整个代码这是我的代码，来自main_activity.java

public class MainActivity extends AppCompatActivity {

private ArrayList<String> items;
private ArrayAdapter<String> itemsAdapter;
private ListView lvItems;
private static final String TAG = "MainActivity";
Button delete;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(layout.activity_main);

    lvItems = (ListView) findViewById(id.lvItems);
    lvItems.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE_MODAL);
    items = new ArrayList<String>();
    itemsAdapter = new ArrayAdapter<String>(this, layout.item_to_do, id.task_title, items);
    lvItems.setAdapter(itemsAdapter);
    items.add("Pierwsza rzecz");
    items.add("Druga rzecz");
    delete = (Button) findViewById(id.action_delete_task);
    setupListViewListener();
}

public void onCheckboxClicked(View view) {
    // Is the view now checked?
    boolean checked = ((CheckBox) view).isChecked();

    // Check which checkbox was clicked
    switch (view.getId()) {
        case id.task_delete:
            if (checked)

                break;
    }
}

private void setupListViewListener() {
    lvItems.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> adapter, View view, int position, long id) {
            items.remove(position);
            itemsAdapter.notifyDataSetChanged();
            return true;
        }
    });
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(final MenuItem item) {
    switch (item.getItemId()) {
        case id.action_add_task:
            final EditText taskEditText = new EditText(this);
            taskEditText.setAllCaps(true);
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.setTitle("Add a new task");
            builder.setMessage("What do you want to do next?");
            builder.setView(taskEditText);
            builder.setPositiveButton("Add", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    String task = String.valueOf(taskEditText.getText());
                    Log.d(TAG, "Task to add: " + task);
                    itemsAdapter.add(task);
                    Snackbar.make(findViewById(id.lvItems), string.add,
                            Snackbar.LENGTH_SHORT)
                            .show();
                }
            });
            builder.setNegativeButton("Cancel", null);
            AlertDialog dialog = builder.create();
            dialog.show();
            return true;

        case id.action_delete_task:
            delete.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    SparseBooleanArray checkedItemPositions = lvItems.getCheckedItemPositions();
                    int itemCount = lvItems.getCount();

                    for (int i = itemCount - 1; i >= 0; i--) {
                        if (checkedItemPositions.get(i)) {
                            itemsAdapter.remove(items.get(i));
                        }
                    }
                    checkedItemPositions.clear();
                    itemsAdapter.notifyDataSetChanged();

                }
            });

        default:
            return super.onOptionsItemSelected(item);
    }
}

}

Answer 1

删除是菜单项，而不是布局中的视图，因此您将不会在其上设置点击侦听器。

删除班级中的删除按钮

就像下面一样

    case id.action_delete_task:
        SparseBooleanArray checkedItemPositions = lvItems.getCheckedItemPositions();
        int itemCount = lvItems.getCount();
        for (int i = itemCount - 1; i >= 0; i--) {
            if (checkedItemPositions.get(i)) {
                itemsAdapter.remove(items.get(i));
            }
        }
        checkedItemPositions.clear();
        itemsAdapter.notifyDataSetChanged();

我在您的代码中也看不到onCreateOption菜单。这用于增加活动中的菜单。

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.your_menu, menu);
    return true;
}

使用ListBox中的CheckBox和“选项”菜单项删除多个项目

1 个答案: