应用程序在主要活动中关闭onBackPressed
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您好我是片段新手..我有一个主要活动和两个片段。如果我在第一个片段的editText中输入数据，它将显示在第二个片段的TextView上。如果我输入数据并重复按下提交按钮，数据也会在第二个片段中更改..但是当我按下后退按钮时，应用程序将关闭。当我按下后退按钮时，我想要显示我先前在片段中输入的数据
这是代码：
FirstFragment extends Fragment {
private OnFragmentInteractionListener mListener;
private EditText inputName;
private EditText inputPhone;
private String userName;
private String userPhone;
public FirstFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_first, container, false);
inputName = (EditText) view.findViewById(R.id.edit_text_name);
inputPhone = (EditText) view.findViewById(R.id.edit_text_phone);
TextView submit = (TextView) view.findViewById(R.id.submit);
submit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (inputName.getText().toString().equals("")) {
Toast.makeText(getActivity(), "Name must be filled", Toast.LENGTH_LONG).show();
return;
}
else if(inputPhone.getText().toString().equals("")){
Toast.makeText(getActivity(),"please enter the phone number" , Toast.LENGTH_SHORT).show();
return;
}
userName = inputName.getText().toString();
userPhone = inputPhone.getText().toString();
onButtonPressed(userName, userPhone);
inputName.setText("");
inputPhone.setText("");
}
});
return view;
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(String nameContent, String phoneContent) {
if (mListener != null) {
mListener.onFragmentInteraction(nameContent, phoneContent);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(String nameContent, String phoneContent);
}
}
SecondFragment extends Fragment {
//private OnFragmentInteractionListener mListener;
private TextView updateName;
private TextView updatePhone;
public SecondFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view= inflater.inflate(R.layout.fragment_second, container, false);
updateName = (TextView)view.findViewById(R.id.text_view_name);
updatePhone = (TextView)view.findViewById(R.id.text_view_phone);
return view;
}
public void updateTextField(String name, String phone){
updateName.setText(name);
updatePhone.setText(phone);
}
}
MainActivity extends AppCompatActivity implements FirstFragment.OnFragmentInteractionListener{
private FragmentActivity activity;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public void onFragmentInteraction(String nameContent, String phoneContent) {
SecondFragment secondFragment = (SecondFragment)getSupportFragmentManager().findFragmentById(R.id.fragment_show);
secondFragment.updateTextField(nameContent, phoneContent);
}
public FragmentActivity getActivity() {
return activity;
}
}
**fragment_first.xml**
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.seasiainfotech.singhjasmeet.passinfragments.views.MainActivity">
<EditText
android:id="@+id/edit_text_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/enter_name"
android:inputType="text"
android:paddingEnd="5dp"
android:paddingStart="5dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintLeft_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.050" />
<EditText
android:id="@+id/edit_text_phone"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/enter_phone"
app:layout_constraintTop_toBottomOf="@+id/edit_text_name"
android:inputType="phone"
android:paddingTop="25dp"
android:paddingStart="5dp"
android:paddingEnd="5dp"/>
<TextView
android:id="@+id/submit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="@+id/edit_text_phone"
android:layout_marginTop="50dp"
android:padding="7dp"
android:text="@string/sbmt"
android:textSize="20sp"
android:textColor="@color/colorAccent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:background="@drawable/button_stroke"/>
</android.support.constraint.ConstraintLayout>
**fragment_Second.xml**
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.seasiainfotech.singhjasmeet.passinfragments.views.MainActivity">
<TextView
android:id="@+id/text_view_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:textSize="30sp"
android:textColor="@color/colorPrimaryDark"/>
<TextView
android:id="@+id/text_view_phone"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="@id/text_view_name"
android:textSize="20sp"
android:padding="8dp"
android:textColor="@color/colorPrimary"/>
</android.support.constraint.ConstraintLayout>
activity_main.xml
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.seasiainfotech.singhjasmeet.passinfragments.views.MainActivity">
<fragment
android:id="@+id/fragment_input"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:name="com.seasiainfotech.singhjasmeet.passinfragments.fragments.FirstFragment"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
<fragment
android:id="@+id/fragment_show"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:name="com.seasiainfotech.singhjasmeet.passinfragments.fragments.SecondFragment"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
app:layout_constraintBottom_toTopOf="@+id/fragment_input"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
答案
覆盖MainActivity中的“onBackPressed”方法
@Override
public void onBackPressed()
{
if(want_to_close_the_app){
//call super
super.onBackPressed();
}
else{
// dont call super
}
}
另一答案
添加片段标记时添加它们。防爆。 FirstFragment的标签是“firstFragment”，SecondFragment的标签是“secondFragment”。在您的活动中获取一个名为current fragment的常见String变量，并在添加片段时更改它。
public class MainActivity extends Activity{
public static String currentFragment = null;
//while adding first fragment
currentFragment = "firstFragment";
//while adding second fragment
currentFragment = "firstFragment";
}
现在在您的活动中覆盖onBackPressed，如下所示。
@Override
public void onBackPressed() {
if(currentFragment.equals("secondFragment"){
//load first fragment
}else{
super.onBackPressed();
}
}
另一答案
覆盖onBackPressed方法。
@Override
public void onBackPressed()
{
super.onBackPressed();// remove this line
...
//enter your code here.
}
并添加此代码。
getSupportFragmentManger().
beginTransaction().
replace().
addToBackStack().
.commit();
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