Android BottomNavigationView menuItem set选中无效

Question

在我的bottomNavigationView中，我可以更改programmaticaly我的菜单项似乎工作的一切，但实际上我的布局与if检查或直接单击选项卡不同。请看下面的差异：

1）menuItem.setChecked(true)：

2）当用户直接点击图标时，它将执行动画并在正确的

上显示

我真正想要的是选择menuItem，就像用户点击一样。不应该通过执行menuItem.setChecked（true）来工作吗？

请考虑菜单项的以下定义布局：

<item android:id="@+id/menu_home"
    android:title="@string/menu_home"
    android:icon="@drawable/ic_home_black_24dp"
    app:showAsAction="ifRoom" />

<item android:id="@+id/menu_hall_of_fame"
    android:title="@string/menu_hall_of_fame"
    android:icon="@drawable/ic_stars_black_24dp"
    app:showAsAction="ifRoom" />

<item android:id="@+id/menu_info"
    android:title="@string/menu_info"
    android:icon="@drawable/ic_info_black_24dp"
    app:showAsAction="ifRoom" />

<item android:id="@+id/menu_settings"
    android:title="@string/menu_settings"
    android:icon="@drawable/ic_settings_black_24dp"
    app:showAsAction="ifRoom" />

以及我如何检查正确的menuItem：

    MenuItem item = mBottomNav.getMenu().findItem(R.id.menu_about);

    // update selected item
    mSelectedItem = item.getItemId();

    // uncheck the other items and select the one.
    for (int i = 0; i< mBottomNav.getMenu().size(); i++) {
        MenuItem menuItem = mBottomNav.getMenu().getItem(i);
        menuItem.setChecked(menuItem.getItemId() == mSelectedItem);


    }

还有另一种方法来执行menuItem的选择吗？我在这里缺少什么？

Answer 1

请参阅此处我发布的所有代码

public class MainActivity extends AppCompatActivity {
private static final String SELECTED_ITEM = "arg_selected_item";

private BottomNavigationView mBottomNav;
private int mSelectedItem;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mBottomNav = (BottomNavigationView) findViewById(R.id.navigation);
    mBottomNav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            selectFragment(item);
            return true;
        }
    });

    MenuItem selectedItem;
    if (savedInstanceState != null) {
        mSelectedItem = savedInstanceState.getInt(SELECTED_ITEM, 0);
        selectedItem = mBottomNav.getMenu().findItem(mSelectedItem);
    } else {
        selectedItem = mBottomNav.getMenu().getItem(0);
    }
    selectFragment(selectedItem);
}

@Override
protected void onSaveInstanceState(Bundle outState) {
    outState.putInt(SELECTED_ITEM, mSelectedItem);
    super.onSaveInstanceState(outState);
}

@Override
public void onBackPressed() {
    MenuItem homeItem = mBottomNav.getMenu().getItem(0);
    if (mSelectedItem != homeItem.getItemId()) {
        // select home item
        selectFragment(homeItem);
    } else {
        super.onBackPressed();
    }
}

private void selectFragment(MenuItem item) {
    Fragment frag = null;
    // init corresponding fragment
    switch (item.getItemId()) {
        case R.id.menu_home:
            frag = MenuFragment.newInstance(getString(R.string.text_home),
                    getColorFromRes(R.color.color_home));
            break;
        case R.id.menu_notifications:
            frag = MenuFragment.newInstance(getString(R.string.text_notifications),
                    getColorFromRes(R.color.color_notifications));
            break;
        case R.id.menu_search:
            frag = MenuFragment.newInstance(getString(R.string.text_search),
                    getColorFromRes(R.color.color_search));
            break;
    }

    // update selected item
    mSelectedItem = item.getItemId();

    // uncheck the other items.
    Menu menu = mBottomNav.getMenu();
    for (int i = 0, size = menu.size(); i < size; i++) {
        MenuItem menuItem = menu.getItem(i);
        ((MenuItemImpl) menuItem).setExclusiveCheckable(false);
        menuItem.setChecked(menuItem.getItemId() == R.id.menu_home);
        ((MenuItemImpl) menuItem).setExclusiveCheckable(true);
    }

    updateToolbarText(item.getTitle());

    if (frag != null) {
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.add(R.id.container, frag, frag.getTag());
        ft.commit();
    }
}

private void updateToolbarText(CharSequence text) {
    ActionBar actionBar = getSupportActionBar();
    if (actionBar != null) {
        actionBar.setTitle(text);
    }
}

private int getColorFromRes(@ColorRes int resId) {
    return ContextCompat.getColor(this, resId);
}

}

您可以使用此代码

Menu menu = mBottomNav.getMenu();
    for (int i = 0, size = menu.size(); i < size; i++) {
        MenuItem menuItem = menu.getItem(i);
        ((MenuItemImpl) menuItem).setExclusiveCheckable(false);
        menuItem.setChecked(menuItem.getItemId() == R.id.menu_home);
        ((MenuItemImpl) menuItem).setExclusiveCheckable(true);
    }