Question

单击布局中的按钮时，如何显示警告对话框？下面的代码如果按钮来自菜单但我需要它从布局按钮起作用。我尝试用case R.id.action_add_task替换case R.id.button（按钮是布局按钮的名称），但它没有'工作。任何帮助将不胜感激。

  @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

    switch (id){
        case R.id.action_add_task:
            AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
            builder.setTitle("Add something");
            builder.setMessage("What do you nat to do?");
            final EditText inputField = new EditText(getActivity());
            builder.setView(inputField);
            builder.setPositiveButton("Add", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    //Get user input
                    String inputTask = inputField.getText().toString();

                    //Get DBHelper to write to database
                    TaskDBHelper helper = new TaskDBHelper(getActivity());
                    SQLiteDatabase db = helper.getWritableDatabase();

                    //Put in the values within a ContentValues.
                    ContentValues values = new ContentValues();
                    values.clear();
                    values.put(TaskContract.TaskEntry.COLUMN_TASK, inputTask);

                    //Insert the values into the Table for Tasks
                    db.insertWithOnConflict(
                            TaskContract.TaskEntry.TABLE_NAME,
                            null,
                            values,
                            SQLiteDatabase.CONFLICT_IGNORE);

                    //Query database again to get updated data
                    Cursor cursor = db.query(TaskContract.TaskEntry.TABLE_NAME,
                            new String[]{TaskContract.TaskEntry._ID, TaskContract.TaskEntry.COLUMN_TASK},
                            null, null, null, null, null);

                    //Swap old data with new data for display
                    mTaskAdapter.swapCursor(cursor);
                }
            });
            builder.setNegativeButton("Cancel", null);
            builder.create().show();
            return true;
    }
    return super.onOptionsItemSelected(item);
}

Answer 1

如果您想在按钮上执行某些操作，请使用：

RecyclerView

这适用于您活动中的任何按钮（不适用于操作栏图标和溢出菜单项）

Answer 2

像这样用XML声明Button

<Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:onClick="handleButton" android:text="Button" />

在Java类中，通过使用在Xml中声明的onClick属性为按钮创建方法来处理单击

`public void handleButton(View view) {
    AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this);
    dialog.setTitle("Your title here");
    dialog.setMessage("Message body");
    dialog.setPositiveButton("OK", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.cancel();

            }
        });
    dialog.show();             
    return ;
}

在onOptionsItemSelected中单击按钮时未显示Alertdialog

2 个答案: