Android 如何在按“后退”按钮时显示警告消息
我想应用程序显示警告消息时,用户按下后退按钮,若用户选择是,它将返回。我在导航图片段中 我在stack Overflow中搜索了很多次,并尝试:Android 如何在按“后退”按钮时显示警告消息,android,android-navigation-editor,Android,Android Navigation Editor,我想应用程序显示警告消息时,用户按下后退按钮,若用户选择是,它将返回。我在导航图片段中 我在stack Overflow中搜索了很多次,并尝试: @Override public void onBackPressed() { AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); builder.setTitle("Save Or Not"); builder.setMessage("D
@Override
public void onBackPressed() {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Save Or Not");
builder.setMessage("Do you want to save this? ");
builder.setPositiveButton("Save", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
/*Go back:-I dont know how*/
}
});
builder.setNegativeButton("Discard",null);
builder.show();
}
但它显示出给予者的错误:
方法不重写其超类中的方法
编辑:
我想在导航图片段中设置onBackPressedListener(手机后退按钮)在按钮clicklistner
MainActivity.super.onBackPressed()中添加此行代码>
将您的活动名称替换为MainActivity
builder.setPositiveButton("Save", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.dismiss();
MainActivity.super.onBackPressed();
//Replace your Activity name insted of MainActivity
}
});
当使用Fragments 1.1.0(现在是alpha格式)时,您可以按照说明如何注册的,它允许您从片段中注册onBackPressed()
回调:
public class MyFragment extends Fragment {
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// This callback will only be called when MyFragment is at least Started.
OnBackPressedCallback callback = new OnBackPressedCallback(true /* enabled by default */) {
@Override
public void handleOnBackPressed() {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Save Or Not");
builder.setMessage("Do you want to save this? ");
builder.setPositiveButton("Save", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// Save your content
save();
// Then pop
NavHostFragment.findNavController(MyFragment.this).popBackStack();
}
builder.setNegativeButton("Discard",null);
builder.show();
});
}
});
requireActivity().getOnBackPressedDispatcher().addCallback(this, callback);
}
}
添加布尔变量isBack=false,如果它说是,则将其设置为true,并检查isBack为false或true的条件,如果为true,则添加super。按back()否则显示alter对话框以不同的函数包装alter对话框您想从片段中获取返回按钮?我需要在导航图片段中输入onBackButtonClickListener-谢谢您的帮助,但我在android导航图片段中,当我键入CreateGame.super.onBackPressed()时;它无法解析它(我也做了getActivity())Android studio没有解析。extends fragmentonbackpress()中的onbackpress()仅用于不在Fragment中的活动,请在其父活动中使用onbackpress来解析该片段。听到这一点,我很难过。感谢您的帮助,我有1.0.0-beta02版本的gradel片段。能否将其从gradel更改为1.1.0更新其版本注意:当从片段中设置OnBackPressedDispatcher时,需要上面的“Requiresponsibility()”前缀,但从活动中设置时,不需要前缀。
public class MyFragment extends Fragment {
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// This callback will only be called when MyFragment is at least Started.
OnBackPressedCallback callback = new OnBackPressedCallback(true /* enabled by default */) {
@Override
public void handleOnBackPressed() {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Save Or Not");
builder.setMessage("Do you want to save this? ");
builder.setPositiveButton("Save", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// Save your content
save();
// Then pop
NavHostFragment.findNavController(MyFragment.this).popBackStack();
}
builder.setNegativeButton("Discard",null);
builder.show();
});
}
});
requireActivity().getOnBackPressedDispatcher().addCallback(this, callback);
}
}