如何使用单选复选框android在AlertDialog中选择一个条目？

Question

我有一个警告对话框,其中包含一个选项列表和两个按钮:一个OK按钮和一个cancel按钮.下面的代码显示了我是如何实现它的.

private final Dialog createListFile(final String[] fileList) {
  AlertDialog.Builder builder = new AlertDialog.Builder(this);
  builder.setTitle("Compare with:");

  builder.setSingleChoiceItems(fileList, -1, new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int whichButton) {
      Log.d(TAG,"The wrong button was tapped: " + fileList[whichButton]);
    }
  });

  builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int whichButton) {}
  });

  builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int whichButton) {}
  });

  return builder.create();
}

我的目标是在点击按钮时获取所选单选按钮的名称OK.我试图将字符串保存在变量中,但在内部类中,可以只访问最终变量.有没有办法避免使用最终变量来存储选定的单选按钮？

Answer 1

使用最终变量显然不起作用(因为它只能在声明时分配一次).所谓的"全局"变量通常是代码气味(特别是当它们成为Activity类的一部分时,通常是创建AlertDialogs的地方).更干净的解决方案是将DialogInterface对象转换为AlertDialog,然后调用getListView().getCheckedItemPosition().像这样:

new AlertDialog.Builder(this)
        .setSingleChoiceItems(items, 0, null)
        .setPositiveButton(R.string.ok_button_label, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
                dialog.dismiss();
                int selectedPosition = ((AlertDialog)dialog).getListView().getCheckedItemPosition();
                // Do something useful withe the position of the selected radio button
            }
        })
        .show();

Answer 2

这已经回答得很好,但我一直在谷歌找到这个答案,我想分享一个非匿名的类解决方案.我自己更喜欢可重复使用的课程,可能对其他人有帮助.

在这个例子中,我正在使用一个DialogFragment实现并通过回调方法检索一个值.

从Dialog获取值的回调方法可以通过创建公共接口来完成

public interface OnDialogSelectorListener {
    public void onSelectedOption(int selectedIndex);
}

另外,DialogFragment工具DialogInterface.OnClickListener,这意味着你可以注册一个已经实现的类OnClickListener为DialogFragment正在创建.

例如

public Dialog onCreateDialog(Bundle savedInstanceState) {
    final AlertDialog.Builder builder = new AlertDialog.Builder(this.getActivity());

    builder.setTitle(R.string.select);
    builder.setSingleChoiceItems(mResourceArray, mSelectedIndex, this);
    builder.setPositiveButton(R.string.ok, this);
    builder.setNegativeButton(R.string.cancel, this);
    return builder.create();
}

这条线

builder.setSingleChoiceItems(mResourceArray, mSelectedIndex, this);

使用mResourceArray中存储的资源数组中的选项创建一个选择对话框.这也预先选择了存储在mSelectedIndex中的选项索引,最后它将自己设置为OnClickListener.(如果这段有点令人困惑,请参阅最后的完整代码)this

现在,您可以在OnClick方法中获取对话框中的值

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

    switch (which) {
        case Dialog.BUTTON_NEGATIVE: // Cancel button selected, do nothing
            dialog.cancel();
            break;

        case Dialog.BUTTON_POSITIVE: // OK button selected, send the data back
            dialog.dismiss();
            // message selected value to registered callbacks with the
                    // selected value.
            mDialogSelectorCallback.onSelectedOption(mSelectedIndex);
            break;

        default: // choice item selected
                    // store the new selected value in the static variable
            mSelectedIndex = which;
            break;
    }
}

这里发生的是当选择一个项目时,它存储在一个变量中.如果用户单击" 取消"按钮,则不会发回任何更新,也不会发生任何更改.如果用户单击"确定"按钮,则会将值返回到Activity通过创建的回调创建的值.

例如,以下是如何从a创建对话框FragmentActivity.

final SelectorDialog sd = SelectorDialog.newInstance(R.array.selector_array, preSelectedValue);
sd.show(getSupportFragmentManager(), TAG);

这里,资源数组_R.array.selector_array_是要在对话框中显示的字符串数组,preSelectedValue是要在打开时选择的索引.

最后,您FragmentActivity将实现OnDialogSelectorListener并将收到回调消息.

public class MyActivity extends FragmentActivity implements OnDialogSelectorListener {
// ....

    public void onSelectedOption(int selectedIndex) {
        // do something with the newly selected index
    }
}

我希望这对某人有帮助,因为我花了很多时间去理解它.这里DialogFragment有一个带回调的完整实现.

public class SelectorDialog extends DialogFragment implements OnClickListener {
    static final String TAG = "SelectorDialog";

    static int mResourceArray;
    static int mSelectedIndex;
    static OnDialogSelectorListener mDialogSelectorCallback;

    public interface OnDialogSelectorListener {
        public void onSelectedOption(int dialogId);
    }

    public static DialogSelectorDialog newInstance(int res, int selected) {
        final DialogSelectorDialog dialog  = new DialogSelectorDialog();
        mResourceArray = res;
        mSelectedIndex = selected;

        return dialog;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);

        try {
            mDialogSelectorCallback = (OnDialogSelectorListener)activity;
        } catch (final ClassCastException e) {
            throw new ClassCastException(activity.toString() + " must implement OnDialogSelectorListener");
        }
    }

    public Dialog onCreateDialog(Bundle savedInstanceState) {
        final AlertDialog.Builder builder = new AlertDialog.Builder(this.getActivity());

        builder.setTitle(R.string.select);
        builder.setSingleChoiceItems(mResourceArray, mSelectedIndex, this);
        builder.setPositiveButton(R.string.ok, this);
        builder.setNegativeButton(R.string.cancel, this);
        return builder.create();
    }

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

        switch (which) {
            case Dialog.BUTTON_NEGATIVE:
                dialog.cancel();
                break;

            case Dialog.BUTTON_POSITIVE:
                dialog.dismiss();
                // message selected value to registered calbacks
                mDialogSelectorCallback.onSelectedOption(mSelectedIndex);
                break;

            default: // choice selected click
                mSelectedIndex = which;
                break;
        }

    }
}

评论中的问题如何从一个Fragment而不是一个来调用它Activity.

首先做一些改动DialogFragment.

删除onAttach事件,因为这不是这种情况下最简单的方法.

添加新方法以添加对回调的引用

public void setDialogSelectorListener (OnDialogSelectorListener listener) {
    this.mListener = listener;
}

在你的实现中实现监听器 Fragment

public class MyFragment extends Fragment implements SelectorDialog.OnDialogSelectorListener {
// ....

    public void onSelectedOption(int selectedIndex) {
        // do something with the newly selected index
    }
}

现在创建一个新实例并传入一个引用Fragment来使用它.

final SelectorDialog sd = SelectorDialog.newInstance(R.array.selector_array, preSelectedValue);
// this is a reference to MyFragment
sd.setDialogSelectorListener(this);
// mActivity is just a reference to the activity attached to MyFragment
sd.show(this.mActivity.getSupportFragmentManager(), TAG);

Answer 3

final CharSequence[] choice = {"Choose from Gallery","Capture a photo"};

int from; //This must be declared as global !

AlertDialog.Builder alert = new AlertDialog.Builder(activity);
alert.setTitle("Upload Photo");
alert.setSingleChoiceItems(choice, -1, new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        if (choice[which] == "Choose from Gallery") {
            from = 1;
        } else if (choice[which] == "Capture a photo") {
            from = 2;
        }
    }
});
alert.setPositiveButton("OK", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        if (from == 0) {
            Toast.makeText(activity, "Select One Choice", 
                        Toast.LENGTH_SHORT).show();
        } else if (from == 1) {
            // Your Code
        } else if (from == 2) {
            // Your Code
        }
    }
});
alert.show();

Answer 4

正如其他人指出的那样， 实现 'com.google.android.material:material:1.0.0'更简单

有关更多信息，请参阅此材料指南。https://material.io/develop/android/docs/getting-started/

CharSequence[] choices = {"Choice1", "Choice2", "Choice3"};
boolean[] choicesInitial = {false, true, false};
AlertDialog.Builder alertDialogBuilder = new MaterialAlertDialogBuilder(getContext())
    .setTitle(title)
    .setPositiveButton("Accept", null)
    .setNeutralButton("Cancel", null)
    .setMultiChoiceItems(choices, choicesInitial, new DialogInterface.OnMultiChoiceClickListener() {
      @Override
      public void onClick(DialogInterface dialog, int which, boolean isChecked) {

      }
    });
alertDialogBuilder.show();