Question

我确信这是一个基本问题，但我的研究没有任何用处。我的新应用程序需要在几种情况下使用“是/否”对话框，而我没有得到对话框如何适应应用程序生命周期。例如，我想创建一个方法来支持这种类型的构造：

if (yesNoAlert("Title", "Do you want to try again?") == true) {
   action1();
} else {
   action2();
}

该方法看起来像这样：

private boolean yesNoAlert(String title, String message) {
    final boolean returnValue;

    DialogInterface.OnClickListener dialogClickListener = new
                       DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            switch (which){
            case DialogInterface.BUTTON_POSITIVE:
                returnValue = true;
                break;

            case DialogInterface.BUTTON_NEGATIVE:
                returnValue=false;
                break;
            }
        }
    };

    alertbox = new AlertDialog.Builder(this);
    alertbox.setMessage(message)
            .setTitle(title)
            .setPositiveButton("Yes", dialogClickListener)
            .setNegativeButton("No", dialogClickListener)
            .show();
}

...但正如你所看到的那样，它还没有完成 - 有许多事情并不是很安静。我遗漏的部分是如何知道对话框已经完成...有什么方法可以使用，以便应用程序可以了解按钮被按下的事实？当然，BUTTON_POSITIVE和BUTTON_NEGATIVE操作会对此做出响应，但我的问题是如何使用指示符返回，以便等待响应的代码将在action1（）或action2中再次获取（），取决于反应。

目前，我认为我的应用程序没有办法确定这一点，甚至也没有一种方法可以从该代码中创建方法/函数。所以我错过了生命周期中的一些重要部分。

我可以在哪里读到这个？当然，互联网上有很多关于此的信息，但对于我来说，作为一个相对新手，就像从消防水带中喝酒一样。

Answer 1

这将使需要采取动态的行动：

private Thread actionToDo;

private void yesNoAlert(String title, String message)
{
    DialogInterface.OnClickListener dialogClickListener = new DialogInterface.OnClickListener()
    {
            @Override
            public void onClick(DialogInterface dialog, int which)
            {
                switch (which)
                {
                    case DialogInterface.BUTTON_POSITIVE:
                    actionToDo.start();
                    break;

                    case DialogInterface.BUTTON_NEGATIVE:
                    break;
                }
            }
    };
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage(message).setPositiveButton("Yes", dialogClickListener).setNegativeButton("No", dialogClickListener).setTitle(title).show();
}

Answer 2

你可以这样做

private boolean yesNoAlert(String title, String message) {
    new AlertDialog.Builder(this).setMessage(message)
        .setTitle(title)
        .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
             public void onClick(DialogInterface dialog, int which) { action1(); }
        })
        .setNegativeButton("No", new DialogInterface.OnClickListener() {
             public void onClick(DialogInterface dialog, int which) { action2(); }
        })
        .show();
}

Answer 3

您可以使用侦听器来实现此目的。就像在android文档中说的那样：

定义一个界面，其中包含您需要支持的操作（onDialogPositiveClick和onDialogNegativeClick）。

公共类NoticeDialogFragment扩展了DialogFragment {

/* The activity that creates an instance of this dialog fragment must
 * implement this interface in order to receive event callbacks.
 * Each method passes the DialogFragment in case the host needs to query it. */
public interface NoticeDialogListener {
    public void onDialogPositiveClick(DialogFragment dialog);
    public void onDialogNegativeClick(DialogFragment dialog);
}

// Use this instance of the interface to deliver action events
NoticeDialogListener mListener;

// Override the Fragment.onAttach() method to instantiate the NoticeDialogListener
@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    // Verify that the host activity implements the callback interface
    try {
        // Instantiate the NoticeDialogListener so we can send events to the host
        mListener = (NoticeDialogListener) activity;
    } catch (ClassCastException e) {
        // The activity doesn't implement the interface, throw exception
        throw new ClassCastException(activity.toString()
                + " must implement NoticeDialogListener");
    }
}
...

}

使显示对话框的类实现您的界面。

公共类MainActivity扩展了FragmentActivity 实现NoticeDialogFragment.NoticeDialogListener { ...

public void showNoticeDialog() {
    // Create an instance of the dialog fragment and show it
    DialogFragment dialog = new NoticeDialogFragment();
    dialog.show(getSupportFragmentManager(), "NoticeDialogFragment");
}

// The dialog fragment receives a reference to this Activity through the
// Fragment.onAttach() callback, which it uses to call the following methods
// defined by the NoticeDialogFragment.NoticeDialogListener interface
@Override
public void onDialogPositiveClick(DialogFragment dialog) {
    // User touched the dialog's positive button
    ...
}

@Override
public void onDialogNegativeClick(DialogFragment dialog) {
    // User touched the dialog's negative button
    ...
}

}

让对话框在正确的时刻调用这些方法（当检测到setPositiveButton或setNegativeButton点击时）。

public class NoticeDialogFragment扩展DialogFragment { ...

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    // Build the dialog and set up the button click handlers
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
    builder.setMessage(R.string.dialog_fire_missiles)
           .setPositiveButton(R.string.fire, new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int id) {
                   // Send the positive button event back to the host activity
                   mListener.onDialogPositiveClick(NoticeDialogFragment.this);
               }
           })
           .setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int id) {
                   // Send the negative button event back to the host activity
                   mListener.onDialogNegativeClick(NoticeDialogFragment.this);
               }
           });
    return builder.create();
}

}

参考http://developer.android.com/guide/topics/ui/dialogs.html#PassingEvents

是/否对话框和生命周期

3 个答案: