按下手机的后退按钮时，底部导航项退出应用程序

如何解决按下手机的后退按钮时，底部导航项退出应用程序

我已经在我的应用程序中实现了底部导航并且它工作正常，但是今天我尝试在进行某些活动时按下手机的后退按钮，在这样做时，我注意到它几乎让我退出应用程序，有没有办法解决这个问题？例如，它不是将我带到应用程序的外部，而是希望它带我回家活动，是否应该使用某种方法来处理这些更改？如果是这样，请告诉我，我的底部导航代码（例如锻炼活动，因为我在 3 个不同的活动中使用底部导航）是：

public class Exercice extends AppCompatActivity {
    DatabaseReference ref;
    ArrayList<Deal> list;
    RecyclerView recyclerView;
    SearchView searchView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_exercice);
        ref = FirebaseDatabase.getInstance().getReference().child("medicines");
        recyclerView = findViewById(R.id.rv);
        searchView = findViewById(R.id.searchview);
       /* RecyclerView.LayoutManager layoutManager = new GridLayoutManager(this,2);
        recyclerView.setLayoutManager(layoutManager);
*/
        //initialize  and assign variables
        BottomNavigationView bottomNavigationView = findViewById(R.id.bottom_navigation);
        //set home selected
        bottomNavigationView.setSelectedItemId(R.id.exercice);
        //preform itemsselectedlistener
        bottomNavigationView.setonNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                switch (item.getItemId()) {
                    case R.id.exercice:
                        finish();
                        return true;
                    case R.id.profile:
                        startActivity(new Intent(getApplicationContext(),MainActivity.class));
                        overridePendingTransition(0,0);
                        finish();

                        return true;
                    case R.id.home:
                        startActivity(new Intent(getApplicationContext(),Home.class));
                        overridePendingTransition(0,0);
                        finish();

                }
                return false;
            }
        });
    }
    @Override
    protected void onStart() {
        super.onStart();

        if(ref != null){
            ref.addValueEventListener(new ValueEventListener() {
                @NonNull
                @Override
                protected Object clone() throws CloneNotSupportedException {
                    return super.clone();
                }

                @Override
                public void onDataChange(@NonNull DataSnapshot snapshot) {
                    if(snapshot.exists()){
                        list = new ArrayList<>();
                        for(DataSnapshot ds : snapshot.getChildren()){
                            list.add(ds.getValue(Deal.class));
                        }
                        AdapterClass adapterClass = new AdapterClass(list);
                        recyclerView.setAdapter(adapterClass);

                    }
                }

                @Override
                public void onCancelled(@NonNull DatabaseError error) {
                    Toast.makeText(Exercice.this,error.getMessage(),Toast.LENGTH_SHORT).show();
                }
            });
        }
        if (searchView != null){
            searchView.setonQueryTextListener(new SearchView.OnQueryTextListener() {
                @Override
                public boolean onQueryTextSubmit(String query) {
                    return false;
                }

                @Override
                public boolean onQueryTextChange(String newText) {
                    search(newText);
                    return true;
                }
            });
        }

    }

    private void search(String str) {
        if (!str.equals("")){
            ArrayList<Deal> myList = new ArrayList<>();
            for (Deal object : list){
                if(object.getdisease().toLowerCase().contains(str.toLowerCase())){
                    myList.add(object);
                }
            }
            AdapterClass adapterClass = new AdapterClass(myList);
            recyclerView.setAdapter(adapterClass);
        }

    }
}