Question

我目前有一个具有MainActivity，带有3个项目的BottomNavigationView和3个相应片段的应用程序：

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。我的问题是循环遍历片段时，输入/退出动画始终相同。

因此，如果我从“首页”转到“收藏夹”，然后返回“首页”，则当我想从左侧输入时，首页将从右侧进入。

是否可以根据用户来自应用程序的位置来设置自定义进入/退出过渡动画？

Answer 1

对于以后找到它的任何人。正如Filippo Vigani建议的那样，我想出了一种跟踪当前位置的方法。这是我所做的：

public class MainActivity extends AppCompatActivity implements
    AddCategoryFragment.AddCategoryFragmentListener{

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    loadFragment(new HomeFragment(), 1);

    // Bottom Nav
    bottomNav = findViewById(R.id.bottom_nav);
    bottomNav.setOnNavigationItemSelectedListener(
            new BottomNavigationView.OnNavigationItemSelectedListener() {
                @Override
                public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
                    Fragment fragment = null;
                    int newPosition = 0;

                    switch (menuItem.getItemId()) {
                        case R.id.bottom_nav_home:
                            fragment = new HomeFragment();
                            newPosition = 1;
                            break;
                        case R.id.bottom_nav_favorites:
                            fragment = new FavoritesFragment();
                            newPosition = 2;
                            break;
                        case R.id.bottom_nav_settings:
                            fragment = new SettingsFragment();
                            newPosition = 3;
                            break;
                    }
                    return loadFragment(fragment, newPosition);
                }
            }
    );
} // End of onCreate


private boolean loadFragment(Fragment fragment, int newPosition) {
    if(fragment != null) {
        if(startingPosition > newPosition) {
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            transaction.setCustomAnimations(R.anim.slide_in_left, R.anim.slide_out_right );
            transaction.replace(R.id.container, fragment);
            transaction.commit();
        }
        if(startingPosition < newPosition) {
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            transaction.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left);
            transaction.replace(R.id.container, fragment);
            transaction.commit();
        }
        startingPosition = newPosition;
        return true;
    }

    return false;
}

Answer 2

对于以后找到它的任何人。我对方法进行了一些修改@Ian Greene。在应用程序启动时有一项禁用动画的检查

 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backPressed

@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();
    }
}

我希望这会对某人有所帮助

 @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);
}

使用BottomNavigationView的片段过渡动画

2 个答案: