java - 使用 BottomNavigationView 的 fragment 过渡动画

Question

我目前有一个应用程序，它有一个 MainActivity、一个包含 3 个项目的 BottomNavigationView 和 3 个相应的 fragment :

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {

    // Bottom Nav
    bottomNav = findViewById(R.id.bottom_nav);
    bottomNav.setOnNavigationItemSelectedListener(
            new BottomNavigationView.OnNavigationItemSelectedListener() {
                @Override
                public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
                    Fragment fragment = null;

                    switch (menuItem.getItemId()) {
                        case R.id.bottom_nav_home:
                            fragment = new HomeFragment();
                            break;
                        case R.id.bottom_nav_favorites:
                            fragment = new FavoritesFragment();
                            break;
                        case R.id.bottom_nav_settings:
                            fragment = new SettingsFragment();
                            break;
                    }
                    return loadFragment(fragment, position);
                }
            }
    );
}

private boolean loadFragment(Fragment fragment) {
    if(fragment != null) {
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left);
        transaction.replace(R.id.container, fragment);
        transaction.commit();
        return true;
    }
    return false;
}

这真的很好用。我的问题是循环浏览 fragment 时，进入/退出动画总是相同的。

因此，如果我从主页转到 Collection 夹，然后返回主页，主页从右侧进入，而我想从左侧进入。

有没有办法根据用户在应用中的来源来设置自定义进入/退出过渡动画？

Answer 1

对于后来发现这个的人。我稍微修改了方法@Ian Greene。应用程序启动时有一个禁用动画的检查

 private boolean loadFragment(Fragment fragment, int newPosition) {
    if(fragment != null) {
        if(newPosition == 0) {
            getSupportFragmentManager()
                    .beginTransaction()
                    .replace(R.id.contentLayout, fragment).commit();

        }
        if(startingPosition > newPosition) {
            getSupportFragmentManager()
                .beginTransaction()
                    .setCustomAnimations(R.anim.slide_in_left, R.anim.slide_out_right )
                .replace(R.id.contentLayout, fragment).commit();

        }
        if(startingPosition < newPosition) {
            getSupportFragmentManager()
                    .beginTransaction()
                    .setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left)
                    .replace(R.id.contentLayout, fragment).commit();

        }
        startingPosition = newPosition;
        return true;
    }

    return false;
}

然后创建

    if (savedInstanceState == null) {
        loadFragment(mFirstFragment, 0);
    }

和后退

@Override
public void onBackPressed() {
    int selectedItemId = bottomNavigationView.getSelectedItemId();
    if (R.id.navigation_home != selectedItemId) {
        loadFragment(mFirstFragment,1);
        toolbar.setTitle(title[0]);
        bottomNavigationView.setSelectedItemId(R.id.navigation_home);
    } else {
        super.onBackPressed();
    }
}

我希望这对某人有帮助

 @Override
public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
    Fragment fragment = null;
    int newPosition = 0;
    if (bottomNavigationView.getSelectedItemId() != menuItem.getItemId()) {
        switch (menuItem.getItemId()) {
            case R.id.navigation_home:
                fragment = mFirstFragment;
                toolbar.setTitle(title[0]);
                newPosition = 1;
                break;
            case R.id.navigation_dashboard:
                fragment = mSecondFragment;
                toolbar.setTitle(title[1]);
                newPosition = 2;
                break;
            case R.id.navigation_notifications:
                fragment = mThirdFragment;
                toolbar.setTitle(title[2]);
                newPosition = 3;
                break;
        }
    }
    return loadFragment(fragment, newPosition);
}