这几天把之前学的所有结合在了一起，做了个简易的APP

总体架构：

 

 

 下面按照顺序上代码

MainActivity

package com.example.calculationtest;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.NavigationUI;

import android.content.DialogInterface;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {
    NavController controller;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        controller= Navigation.findNavController(this,R.id.fragment2);
        NavigationUI.setupActionBarWithNavController(this,controller);
    }

    @Override
    public boolean onSupportNavigateUp() {
        if(controller.getCurrentDestination().getId()==R.id.questionFragment){
            AlertDialog.Builder builder=new AlertDialog.Builder(this);
            builder.setTitle(getString(R.string.quit_dialog_title));
            builder.setPositiveButton(R.string.dialog_positive_message, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    controller.navigateUp();
                }
            });
            builder.setNegativeButton(R.string.dialog_negative_message, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {

                }
            });
            AlertDialog dialog=builder.create();
            dialog.show();

        }else{
            controller.navigate(R.id.titleFragment);
        }
        return super.onSupportNavigateUp();
    }

    @Override
    public void onBackPressed() {
        if(controller.getCurrentDestination().getId()==R.id.titleFragment){
            super.onBackPressed();
        }else{
            onSupportNavigateUp();
        }
    }
}

MainActivity.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">

    <fragment
        android:id="@+id/fragment2"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/nav" />
</androidx.constraintlayout.widget.ConstraintLayout>

TitleFragment

package com.example.calculationtest;


import android.content.Intent;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.databinding.DataBindingUtil;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.SavedStateViewModelFactory;
import androidx.lifecycle.ViewModelProvider;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.example.calculationtest.databinding.FragmentTitleBinding;


/**
 * A simple {@link Fragment} subclass.
 */
public class TitleFragment extends Fragment {


    public TitleFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        MyViewModel myViewModel;
        myViewModel=new ViewModelProvider(requireActivity(),new SavedStateViewModelFactory(requireActivity().getApplication(),this)).get(MyViewModel.class);
        FragmentTitleBinding binding;
        binding= DataBindingUtil.inflate(inflater,R.layout.fragment_title,container,false);
        binding.setData(myViewModel);
        binding.setLifecycleOwner(requireActivity());
        binding.button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                NavController controller= Navigation.findNavController(view);
                controller.navigate(R.id.action_titleFragment_to_questionFragment);
            }
        });
        return binding.getRoot();

        // Inflate the layout for this fragment
        //return inflater.inflate(R.layout.fragment_title, container, false);
    }

}

TitleFragment.xml

<?xml version="1.0" encoding="utf-8"?>
<layout 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">

    <data>
        <variable
            name="data"
            type="com.example.calculationtest.MyViewModel" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".TitleFragment">

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintGuide_percent="0.1" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintGuide_percent="0.9" />

        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/title_message"
            android:textSize="@dimen/huge_font"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toStartOf="@+id/guideline2"
            app:layout_constraintStart_toStartOf="@+id/guideline"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.15" />

        <ImageView
            android:id="@+id/imageView"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_marginStart="50dp"
            android:layout_marginEnd="50dp"
            android:contentDescription="@string/title_image_info"
            android:src="@drawable/suanshu"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintDimensionRatio="1:1"
            app:layout_constraintEnd_toStartOf="@+id/guideline2"
            app:layout_constraintStart_toStartOf="@+id/guideline"
            app:layout_constraintTop_toTopOf="parent" />

        <Button
            android:id="@+id/button"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="@string/title_nuton_message"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toStartOf="@+id/guideline2"
            app:layout_constraintHorizontal_bias="0.497"
            app:layout_constraintStart_toStartOf="@+id/guideline"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.83" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{@string/higeh_score(data.highScore)}"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.982"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.04"
            tools:text="123" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

 QuestionFragment

package com.example.calculationtest;


import android.os.Bundle;

import androidx.databinding.DataBindingUtil;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.SavedStateViewModelFactory;
import androidx.lifecycle.ViewModelProvider;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.example.calculationtest.databinding.FragmentQuestionBinding;


/**
 * A simple {@link Fragment} subclass.
 */
public class QuestionFragment extends Fragment {


    public QuestionFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        final MyViewModel myViewModel;
        myViewModel = new ViewModelProvider(getActivity(), new SavedStateViewModelFactory(getActivity().getApplication(), this)).get(MyViewModel.class);
        myViewModel.generator();
        myViewModel.getCurrentScore().setValue(0);
        final FragmentQuestionBinding binding;
        binding = DataBindingUtil.inflate(inflater, R.layout.fragment_question, container, false);
        binding.setData(myViewModel);
        binding.setLifecycleOwner(requireActivity());
        final StringBuilder builder = new StringBuilder();
        View.OnClickListener listener = new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                switch (view.getId()) {
                    case R.id.button0:
                        builder.append("0");
                        break;
                    case R.id.button1:
                        builder.append("1");
                        break;
                    case R.id.button2:
                        builder.append("2");
                        break;
                    case R.id.button3:
                        builder.append("3");
                        break;
                    case R.id.button4:
                        builder.append("4");
                        break;
                    case R.id.button5:
                        builder.append("5");
                        break;
                    case R.id.button6:
                        builder.append("6");
                        break;
                    case R.id.button7:
                        builder.append("7");
                        break;
                    case R.id.button8:
                        builder.append("8");
                        break;
                    case R.id.button9:
                        builder.append("9");
                        break;
                    case R.id.button_clear:
                        builder.setLength(0);
                        break;
                }
                if (builder.length() == 0) {
                    binding.textView9.setText(R.string.input_indicator);
                } else {
                    binding.textView9.setText(builder.toString());
                }
            }
        };
        binding.button0.setOnClickListener(listener);
        binding.button1.setOnClickListener(listener);
        binding.button2.setOnClickListener(listener);
        binding.button3.setOnClickListener(listener);
        binding.button4.setOnClickListener(listener);
        binding.button5.setOnClickListener(listener);
        binding.button6.setOnClickListener(listener);
        binding.button7.setOnClickListener(listener);
        binding.button8.setOnClickListener(listener);
        binding.button9.setOnClickListener(listener);
        binding.buttonClear.setOnClickListener(listener);
        binding.buttonSubmit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(builder.length()!=0){
                if (Integer.valueOf(builder.toString()).intValue() == myViewModel.getAnswer().getValue()) {
                    myViewModel.answerCorrect();
                    builder.setLength(0);
                    binding.textView9.setText(R.string.answer_correct_message);
                    //builder.append(getString(R.string.answer_correct_message));
                } else {
                    NavController controller = Navigation.findNavController(view);
                    if (myViewModel.win_flag) {
                        controller.navigate(R.id.action_questionFragment_to_winFragment);
                        myViewModel.win_flag = (false);
                        myViewModel.save();
                    } else {
                        controller.navigate(R.id.action_questionFragment_to_loseFragment);
                    }
                }
            }else{
                binding.textView9.setText("请输入你的答案");
            }}
        });

        return binding.getRoot();
        // Inflate the layout for this fragment
        //return inflater.inflate(R.layout.fragment_question, container, false);
    }

}

QuestionFragment.xml

<?xml version="1.0" encoding="utf-8"?>
<layout 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">

    <data>
        <variable
            name="data"
            type="com.example.calculationtest.MyViewModel" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".QuestionFragment">

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.1" />

        <TextView
            android:id="@+id/textView3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{@string/current_score(data.currentScore)}"
            app:layout_constraintBottom_toTopOf="@+id/guideline3"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline3"
            tools:text="Score5" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.2" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.32" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.4" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline7"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.8" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintGuide_percent="0.1" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline9"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            app:layout_constraintGuide_percent="0.9" />

        <TextView
            android:id="@+id/textView4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="@dimen/big_front"
            android:text="@{String.valueOf(data.leftNumber)}"
            app:layout_constraintBottom_toBottomOf="@+id/textView5"
            app:layout_constraintEnd_toStartOf="@+id/textView5"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="@+id/guideline8"
            app:layout_constraintTop_toTopOf="@+id/textView5"
            tools:text="8" />

        <TextView
            android:id="@+id/textView5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="@dimen/big_front"
            android:text="@{data.operator}"
            app:layout_constraintBottom_toBottomOf="@+id/textView6"
            app:layout_constraintEnd_toStartOf="@+id/textView6"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/textView4"
            app:layout_constraintTop_toTopOf="@+id/textView6"
            tools:text="+" />

        <TextView
            android:id="@+id/textView6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="@dimen/big_front"
            android:text="@{String.valueOf(data.rightNumber)}"
            app:layout_constraintBottom_toBottomOf="@+id/textView7"
            app:layout_constraintEnd_toStartOf="@+id/textView7"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/textView5"
            app:layout_constraintTop_toTopOf="@+id/textView7"
            tools:text="9" />

        <TextView
            android:id="@+id/textView7"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/equal_symbol"
            android:textSize="@dimen/big_front"
            app:layout_constraintBottom_toBottomOf="@+id/textView8"
            app:layout_constraintEnd_toStartOf="@+id/textView8"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/textView6"
            app:layout_constraintTop_toTopOf="@+id/textView8"
            tools:text="=" />

        <TextView
            android:id="@+id/textView8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/qusetion_mark"
            android:textSize="@dimen/big_front"
            app:layout_constraintBottom_toTopOf="@+id/guideline4"
            app:layout_constraintEnd_toStartOf="@+id/guideline9"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/textView7"
            app:layout_constraintTop_toTopOf="@+id/guideline4"
            tools:text="\?" />

        <TextView
            android:id="@+id/textView9"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/input_indicator"
            android:textSize="@dimen/mid_front"
            app:layout_constraintBottom_toTopOf="@+id/guideline5"
            app:layout_constraintEnd_toStartOf="@+id/guideline9"
            app:layout_constraintStart_toStartOf="@+id/guideline8"
            app:layout_constraintTop_toTopOf="@+id/guideline5"
            tools:text="Your Answer" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline10"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.5" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline11"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.6" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline12"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.7" />

        <Button
            android:id="@+id/button3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button3"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toBottomOf="@+id/button2"
            app:layout_constraintEnd_toStartOf="@+id/guideline9"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/button2"
            app:layout_constraintTop_toTopOf="@+id/button2"
            app:layout_constraintVertical_bias="0.0" />

        <Button
            android:id="@+id/button1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button1"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toTopOf="@+id/guideline10"
            app:layout_constraintEnd_toStartOf="@+id/button2"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="@+id/guideline8"
            app:layout_constraintTop_toTopOf="@+id/guideline6" />

        <Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button2"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toBottomOf="@+id/button1"
            app:layout_constraintEnd_toStartOf="@+id/button3"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/button1"
            app:layout_constraintTop_toTopOf="@+id/button1"
            app:layout_constraintVertical_bias="0.0" />

        <Button
            android:id="@+id/button4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button4"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toTopOf="@+id/guideline11"
            app:layout_constraintEnd_toStartOf="@+id/button5"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="@+id/guideline8"
            app:layout_constraintTop_toTopOf="@+id/guideline10" />

        <Button
            android:id="@+id/button5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button5"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toBottomOf="@+id/button4"
            app:layout_constraintEnd_toStartOf="@+id/button6"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/button4"
            app:layout_constraintTop_toTopOf="@+id/button4" />

        <Button
            android:id="@+id/button6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button6"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toBottomOf="@+id/button5"
            app:layout_constraintEnd_toStartOf="@+id/guideline9"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/button5"
            app:layout_constraintTop_toTopOf="@+id/button5" />

        <Button
            android:id="@+id/button7"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button7"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toTopOf="@+id/guideline12"
            app:layout_constraintEnd_toStartOf="@+id/button8"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="@+id/guideline8"
            app:layout_constraintTop_toTopOf="@+id/guideline11" />

        <Button
            android:id="@+id/button8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button8"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toBottomOf="@+id/button7"
            app:layout_constraintEnd_toStartOf="@+id/button9"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/button7"
            app:layout_constraintTop_toTopOf="@+id/button7" />

        <Button
            android:id="@+id/button9"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button9"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toBottomOf="@+id/button8"
            app:layout_constraintEnd_toStartOf="@+id/guideline9"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/button8"
            app:layout_constraintTop_toTopOf="@+id/button8" />

        <Button
            android:id="@+id/button_clear"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button_clear"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toTopOf="@+id/guideline7"
            app:layout_constraintEnd_toStartOf="@+id/button0"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="@+id/guideline8"
            app:layout_constraintTop_toTopOf="@+id/guideline12" />

        <Button
            android:id="@+id/button0"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button0"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toBottomOf="@+id/button_clear"
            app:layout_constraintEnd_toStartOf="@+id/button_submit"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/button_clear"
            app:layout_constraintTop_toTopOf="@+id/button_clear" />

        <Button
            android:id="@+id/button_submit"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button_submit"
            android:textSize="@dimen/button_font"
            app:layout_constraintBottom_toBottomOf="@+id/button0"
            app:layout_constraintEnd_toStartOf="@+id/guideline9"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toEndOf="@+id/button0"
            app:layout_constraintTop_toTopOf="@+id/button0" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

WinFragment

age com.example.calculationtest;


import android.os.Bundle;

import androidx.databinding.DataBindingUtil;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.SavedStateViewModelFactory;
import androidx.lifecycle.ViewModelProvider;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.example.calculationtest.databinding.FragmentWinBinding;


/**
 * A simple {@link Fragment} subclass.
 */
public class WinFragment extends Fragment {


    public WinFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, final ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        MyViewModel myViewModel=new ViewModelProvider(getActivity(),new SavedStateViewModelFactory(getActivity().getApplication(),this)).get(MyViewModel.class);
        FragmentWinBinding binding;
        binding= DataBindingUtil.inflate(inflater,R.layout.fragment_win,container,false);
        binding.setData(myViewModel);
        binding.setLifecycleOwner(requireActivity());
        binding.button11.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                NavController controller= Navigation.findNavController(view);
                controller.navigate(R.id.action_winFragment_to_titleFragment);
            }
        });
        return binding.getRoot();
    }

}

WinFragment.xml

<?xml version="1.0" encoding="utf-8"?>
<layout 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">

    <data>
        <variable
            name="data"
            type="com.example.calculationtest.MyViewModel" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".WinFragment">

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline16"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.45" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline17"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.1" />

        <ImageView
            android:id="@+id/imageView3"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:src="@drawable/ic_sentiment_satisfied_black_24dp"
            app:layout_constraintBottom_toTopOf="@+id/guideline16"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline17"
            android:contentDescription="@string/win_image" />

        <TextView
            android:id="@+id/textView12"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/win_message"
            android:textSize="@dimen/huge_font"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline16"
            app:layout_constraintVertical_bias="0.1" />

        <TextView
            android:id="@+id/textView13"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{@string/win_score(data.highScore)}"
            android:textSize="@dimen/huge_font"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline16"
            app:layout_constraintVertical_bias="0.3"
            tools:text="123" />

        <Button
            android:id="@+id/button11"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button_back"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline16"
            app:layout_constraintVertical_bias="0.581" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

LoseFragment

package com.example.calculationtest;


import android.os.Bundle;

import androidx.databinding.DataBindingUtil;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.SavedStateViewModelFactory;
import androidx.lifecycle.ViewModelProvider;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.example.calculationtest.databinding.FragmentLoseBinding;
import com.example.calculationtest.databinding.FragmentWinBinding;


/**
 * A simple {@link Fragment} subclass.
 */
public class LoseFragment extends Fragment {


    public LoseFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, final ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        MyViewModel myViewModel;
        myViewModel=new ViewModelProvider(getActivity(),new SavedStateViewModelFactory(getActivity().getApplication(),this)).get(MyViewModel.class);
        FragmentLoseBinding binding;
        binding= DataBindingUtil.inflate(inflater,R.layout.fragment_lose,container,false);
        binding.setData(myViewModel);
        binding.setLifecycleOwner(requireActivity());
        binding.button10.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                NavController controller= Navigation.findNavController(view);
                controller.navigate(R.id.action_loseFragment_to_titleFragment);
            }
        });
        return binding.getRoot();
    }

}

LoseFragment.xml

<?xml version="1.0" encoding="utf-8"?>
<layout 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">

    <data>
        <variable
            name="data"
            type="com.example.calculationtest.MyViewModel" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".LoseFragment">

        <TextView
            android:id="@+id/textView11"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{@string/lose_score(data.currentScore)}"
            android:textSize="@dimen/huge_font"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline14"
            app:layout_constraintVertical_bias="0.3"
            tools:text="231" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline13"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.1" />

        <androidx.constraintlayout.widget.Guideline
            android:id="@+id/guideline14"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            app:layout_constraintGuide_percent="0.45" />

        <ImageView
            android:id="@+id/imageView2"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:src="@drawable/ic_sentiment_dissatisfied_black_24dp"
            app:layout_constraintBottom_toTopOf="@+id/guideline14"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline13"
            android:contentDescription="@string/lose_image" />

        <TextView
            android:id="@+id/textView10"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/lose_message"
            android:textSize="@dimen/huge_font"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline14"
            app:layout_constraintVertical_bias="0.1" />

        <Button
            android:id="@+id/button10"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/button_back"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="@+id/guideline14"
            app:layout_constraintVertical_bias="0.709" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

MyViewModel

package com.example.calculationtest;

import android.app.Application;
import android.content.Context;
import android.content.SharedPreferences;

import androidx.annotation.NonNull;
import androidx.lifecycle.AndroidViewModel;
import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.SavedStateHandle;

import java.util.Random;

public class MyViewModel extends AndroidViewModel {
    private SavedStateHandle handle;
    private static String KEY_HIGH_SCORE="key_high_score";
    private static String KEY_LEFT_NUMBER="key_left_number";
    private static String KEY_RIGHT_NUMBER="key_right_number";
    private static String KEY_OPERATOR="key_operator";
    private static String KEY_ANSWER="key_answer";
    private static String SAVE_SHP_DATA_NAME="save_shp_data_name";
    private static String KEY_CURRENT_SCORE="key_current_score";
    boolean win_flag=false;
        public MyViewModel(@NonNull Application application, SavedStateHandle handle) {
        super(application);
        if(!handle.contains(KEY_HIGH_SCORE)){
            SharedPreferences shp=getApplication().getSharedPreferences(SAVE_SHP_DATA_NAME, Context.MODE_PRIVATE);
            handle.set(KEY_HIGH_SCORE,shp.getInt(KEY_HIGH_SCORE,0));
            handle.set(KEY_LEFT_NUMBER,0);
            handle.set(KEY_RIGHT_NUMBER,0);
            handle.set(KEY_OPERATOR,"+");
            handle.set(KEY_ANSWER,0);
            handle.set(KEY_CURRENT_SCORE,0);
        }
        this.handle=handle;
    }
    public MutableLiveData<Integer>getLeftNumber(){
            return handle.getLiveData(KEY_LEFT_NUMBER);
    }
    public MutableLiveData<Integer>getRightNumber(){
        return handle.getLiveData(KEY_RIGHT_NUMBER);
    }
    public MutableLiveData<String>getOperator(){
        return handle.getLiveData(KEY_OPERATOR);
    }
    public MutableLiveData<Integer>getHighScore(){
        return handle.getLiveData(KEY_HIGH_SCORE);
    }
    public MutableLiveData<Integer>getCurrentScore(){
        return handle.getLiveData(KEY_CURRENT_SCORE);
    }
    public MutableLiveData<Integer>getAnswer(){
            return handle.getLiveData(KEY_ANSWER);
    }
    void generator(){
            int LEVEL=20;
        Random random=new Random();
        int x,y;
        x=random.nextInt(LEVEL)+1;
        y=random.nextInt(LEVEL)+1;
        if(x%2==0){
            getOperator().setValue("+");
            if(x>y){
                getAnswer().setValue(x);
                getLeftNumber().setValue(y);
                getRightNumber().setValue(x-y);
            }else{
                getAnswer().setValue(y);
                getLeftNumber().setValue(x);
                getRightNumber().setValue(y-x);
            }

        }else{
            getOperator().setValue("-");
            if(x>y){
                getAnswer().setValue(x-y);
                getLeftNumber().setValue(x);
                getRightNumber().setValue(y);
            }else{
                getAnswer().setValue(y-x);
                getLeftNumber().setValue(y);
                getRightNumber().setValue(x);
            }
        }

    }
    void save(){
            SharedPreferences shp=getApplication().getSharedPreferences(SAVE_SHP_DATA_NAME,Context.MODE_PRIVATE);
            SharedPreferences.Editor editor=shp.edit();
            editor.putInt(KEY_HIGH_SCORE,getHighScore().getValue());
            editor.apply();
    }
    void answerCorrect(){
            getCurrentScore().setValue(getCurrentScore().getValue()+1);
            if(getCurrentScore().getValue()>getHighScore().getValue()){
                getHighScore().setValue(getCurrentScore().getValue());
                win_flag=true;
            }
            generator();
    }
}