为什么我添加了数据，主页不显示？

//主页代码
public class MainActivity extends AppCompatActivity {
    protected void onCreate(Bundle savedInstanceState) {
        ······
        //自定义标题栏
        titleBarLayout = findViewById(R.id.title_add_layout);
        ······
        //自定义标题栏添加按钮监听
        titleBarLayout.addBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
            //将类型列表传入，跳转到添加页面
            Intent intent = new Intent(MainActivity.this,AddDishActivity.class);
            intent.putExtra("types",groupList);
            startActivityForResult(intent,0);
            }
      });
   }
        //获取从添加页返回的数据
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode==0) {
            if (resultCode==1) {
                //将数据添加到数据库
            Dish dish = data.getParcelableExtra("dish");
            ContentValues values = new ContentValues();
            values.put("dish_id", dish.getDishId());
            values.put("dish_type", dish.getDishType());
            values.put("dish_name", dish.getDishName());
            getContentResolver().insert(Uri.parse("content://com.imooc.menuprovider"), values);
                }
            }
        }
        ······
}

//添加页代码
public class AddDishActivity extends AppCompatActivity {
    private Spinner typeSpinner;
        private EditText dishNameEt;
        private Button saveDishNameBtn;
        
        private ArrayList<String> typeList;
        private Dish dish;
    
        private String newDishName;

        private TitleBarLayout titleBarLayout;
        
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_add_dish);
           
            titleBarLayout = findViewById(R.id.title_back_layout);
            titleBarLayout.addBtnGone();

            typeSpinner = findViewById(R.id.type_spinner);
            dishNameEt = findViewById(R.id.dish_name_et);
            saveDishNameBtn = findViewById(R.id.save_dishName_btn);
            typeList = getIntent().getStringArrayListExtra("types");

            ArrayAdapter mSpinnerAdapter = new ArrayAdapter<>(this,android.R.layout.simple_spinner_item,typeList);
            mSpinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            typeSpinner.setAdapter(mSpinnerAdapter);

            typeSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
                    //新建对象，从spinner获取id和type
                    dish = new Dish();
                    dish.setDishId(i+1);
                    dish.setDishType(typeList.get(i+1));
            }
            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {
            }
    });

    //保存按钮的监听事件
    saveDishNameBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            newDishName = dishNameEt.getText().toString().trim();
            dish.setDishName(newDishName);
            if (!newDishName.isEmpty()) {
                Intent intent = new Intent();
                intent.putExtra("dish",dish);
                setResult(1,intent);

                Toast.makeText(AddDishActivity.this, "保存成功", Toast.LENGTH_SHORT).show();
            }
        }
    });

    //返回按钮的监听事件
    titleBarLayout.backBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });
    }
}