Prevent back button from closing a dialog box

问题

I am trying to prevent an AlertDialog box from closing when pressing the back button in Android. I have followed both of the popular methods in this thread, and with System.out.println I can see that in both cases the code executes. However, the back button still closes the dialog box.

What could I be doing wrong? Ultimately I'm trying to prevent the back button closing a dialog box - it is a disclaimer that is displayed the first time the app is run and I don't want the user to have any option but to press the "Accept" button in order for the app to continue.

回答1:

Simply use the setCancelable() feature:

AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setCancelable(false);

This prevents the back button from closing the dialog, but leaves the "negative" button intact if you chose to use it.

---

While any user that does not want to accept your terms of service can push the home button, in light of Squonk's comment, here two more ways to prevent them from "backing out" of the user agreement. One is a simple "Refuse" button and the other overrides the back button in the dialog:

builder.setNegativeButton("Refuse", new OnClickListener() {
           @Override
           public void onClick(DialogInterface dialog, int which) {
               finish();
           }
       })
       .setOnKeyListener(new OnKeyListener() {
           @Override
           public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
               if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_UP)
                   finish();
               return false;
           }
       });

回答2:

To prevent the back button closes a Dialog (without depending on Activity), just the following code:

alertDialog.setOnKeyListener(new DialogInterface.OnKeyListener() {
    @Override
    public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
        // Prevent dialog close on back press button
        return keyCode == KeyEvent.KEYCODE_BACK;
    }
});

回答3:

When using DialogFragment you will need to call setCancelable() on the fragment, not the dialog:

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    dialog = new ProgressDialog(getActivity());
    dialog.setIndeterminate(true);
    dialog.setMessage(...);
    setCancelable(false);

    return dialog;
}

Calling dialog.setCancelable() seem to have no effect. It seems that DialogFragment does not takes notice of the dialog's setting for cancelability.

回答4:

Use setCancelable(false)

SampleDialog sampleDialog = SampleDialog.newInstance();
sampleDialog.setCancelable(false);
sampleDialog.show(getSupportFragmentManager(), SampleDialog.class.getSimpleName());

回答5:

Only this worked for me:

AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle(title);
builder.setMessage(content);

/**
 * Make it when the Back button is pressed, the dialog isn't dismissed.
 */
builder.setOnKeyListener(new DialogInterface.OnKeyListener() {
    @Override
    public boolean onKey(DialogInterface dialog, int keyCode, KeyEvent event) {
        if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_UP) {
            Utilities.makeToast(getContext(), "There is no way back!");
            return true; // Consumed
        }
        else {
            return false; // Not consumed
        }
    }
});

Dialog dialog = builder.create();

/**
 * Make it so touching on the background activity doesn't close the dialog
 */
dialog.setCanceledOnTouchOutside(false);

return dialog;

As you can see, I also added a dialog.setCanceledOnTouchOutside(false); line so tapping outside of the dialog doesn't result in it being closed either.

回答6:

In JQuery Mobile a popup adds a hash to the url, the following code allows the back to dismiss the popup when open and return to the app when closed. You could use the same logic for a custom ui framework.

@Override
public void onBackPressed() {

    // check if modal is open #&ui-state=dialog

    if (webView.getVisibility() == View.VISIBLE && webView.getUrl().contains("#&ui-state=dialog")) {
        // don't pass back button action
        if (webView.canGoBack()) {
            webView.goBack();
        }
    } else {
        // pass back button action
        super.onBackPressed();
    }
}

来源：https://stackoverflow.com/questions/12150646/prevent-back-button-from-closing-a-dialog-box