显示对话框并启动onBackPressed上的新活动 - Android

Question

如何在后退按钮上显示确认dialog以转到另一个activity？我正在 The constructor Intent(new DialogInterface.OnClickListener(){}, Class<MainActivity>) is undefined new Intent(this, MainActivity.class);

上的错误

@Override
        public void onBackPressed() {
                    new    AlertDialog.Builder(this).setIcon(android.R.drawable.ic_dialog_alert).setTitle("Confirm Navigation")
                            .setMessage("are you sure you want to goto main menu?")
                            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {

                                    Intent intent = new Intent(this, MainActivity.class);
                                    startActivity(intent);
                                }
                            }).setNegativeButton("No", null).show();
                }

Answer 1

更改此

 Intent intent = new Intent(this, MainActivity.class);

到

Intent intent = new Intent(ActivityName.this, MainActivity.class);

this不是有效的上下文。