Question

使用碎片时处理方向更改的正确方法是什么？

我有一个包含2个片段的横向布局（在FrameLayout的代码中实例化）。当我切换到纵向模式（其布局仅包含仅保留左窗格的一个FrameLayout）时，不再需要右侧片段。

我收到错误：

E/AndroidRuntime(4519): Caused by: java.lang.IllegalArgumentException: No view found for id 0x7f060085 for fragment myFragment{418a2200 #2 id=0x7f060085}

假设是我的活动试图将片段重新附加到方向更改之前的位置，但由于包含片段的视图在纵向模式下不存在，因此会抛出错误。

我尝试了以下隐藏/删除/分离方法但仍然出错。告诉片段不再需要它的正确方法是什么，不要尝试显示？

@Override
public void onCreate(Bundle b) {
    super.onCreate(b);
    Fragment f = getSupportFragmentManager().findFragmentById(R.id.fragholder2);

    //rightPane is a framelayout that holds my fragment.
    if (rightPane == null && f != null) {
         FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
         ft.hide(f);     // This doesnt work
         ft.remove(f);   // neither does this
         ft.detach(f);   // or this
         ft.commit;
    }
}

Answer 1

我遇到了同样的问题，我想我想出了另一个解决方案。此解决方案可能更好，因为您不必将片段添加到后台堆栈。

在调用Activity.onSaveInstanceState() 之前，在super.onSaveInstanceState() 中删除活动中的右侧片段。这对我有用：

public MyActivity extends Activity { @Override public onCreate(Bundle state) { super.onCreate(state); // Set content view setContentView(R.layout.my_activity); // Store whether this is a dual pane layout mDualPane = findViewById(R.id.rightFragHolder) != null; // Other stuff, populate the left fragment, etc. . . . if (mDualPane) { mRightFragment = new RightFragment(); FragmentManager fm = getFragmentManager(); FragmentTransaction ft = fm.beginTransaction(); ft.replace(R.id.rightFragHolder, mRightFragment); ft.commit() } } @Override public void onSaveInstanceState(Bundle state) { if (mDualPane) { FragmentManager fm = getFragmentManager(); FragmentTransaction ft = fm.beginTransaction(); ft.remove(mRightFragment); ft.commit() } super.onSaveInstanceState(state); } private boolean mDualPane; private Fragment mRightFragment; }

Answer 2

如果要保留片段，请尝试不保留片段。

setRetainInstance(false)

而不是

setRetainInstance(true)

Answer 3

通常，您将拥有两个片段（左/右），一个主要活动和一个右侧片段的容器活动（仅在电话设备上显示时）。此博客条目中描述了这一点：The Android 3.0 Fragments API

public class MyActivity extends FragmentActivity
    implements MyListFragment.MyContextItemSelectedListener {

    @Override
    public void onCreate(final Bundle bundle) {
        super.onCreate(bundle);

        setContentView(R.layout.activity);
    }

    // Callback from ListFragment
    @Override
    public void myContextItemSelected(final int action, final long id) {
        if (action == R.id.men_show) {
            processShow(id);
        }
    }

    private void processShow(final long id) {
        if (Tools.isXlargeLand(getApplicationContext())) {
            Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.right);
            if (fragment == null ||
                    fragment instanceof MyEditFragment ||
                    (fragment instanceof MyShowFragment && ((MyShowFragment) fragment).getCurrentId() != id)) {
                fragment = new MyShowFragment(id);

                FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
                transaction.replace(R.id.right, fragment);
                transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
                transaction.commit();
            }
        } else {
            Intent intent = new Intent();
            intent.setClass(this, MyShowActivity.class);
            intent.putExtra("ID", id);
            startActivityForResult(intent, MyConstants.DLG_TABLE1SHOW);
        }
    }

    private static boolean isXlargeLand(final Context context) {
        Configuration configuration = context.getResources().getConfiguration();

        return (((configuration.screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK) == Configuration.SCREENLAYOUT_SIZE_XLARGE) &&
                        configuration.orientation == Configuration.ORIENTATION_LANDSCAPE);
    }
}

Answer 4

如果您有一个带有左窗格和右窗格的双窗格活动，并且其中一个窗格（通常是右窗格）假设在设备切换到纵向模式时不显示，请让Android执行其操作并重新创建右窗格。但是在右窗格的onCreateView中，您应该做的第一件事是检查窗格使用的布局元素之一是否可用。如果不是，请使用FragmentManager删除片段并立即返回：

[Authorize]
    [HttpPatch]
    [Route("current/customer/{id}")]
    public async Task ChangeSessionCustomer(int id)
    {
        var context = HttpContext.Current;
        IAuthenticationManager AuthenticationManager = context.GetOwinContext().Authentication;
        var identity = (ClaimsIdentity)User.Identity;

        var claimCustomerId = identity.FindFirst("CustomerId");
        identity.RemoveClaim(claimCustomerId);
        identity.AddClaim(new Claim("CustomerId", id.ToString()));

    }

Answer 5

我想我已经解决了。

我将片段添加到后台堆栈，然后在活动关闭之前再将其弹出，这有效地消除了它。似乎到目前为止工作。

Answer 6

Android会在屏幕旋转期间重新创建两个片段。但是如果你将下面的检查添加到onCreateView（）中，它将阻止你解决问题：

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
                             @Nullable Bundle savedInstanceState) {
        if (container == null) {
            // Currently in a layout without a container, so no
            // reason to create our view.
            return null;
        }

        // inflate view and do other stuff
    }

我是从Android Developers blog获取的。

Answer 7

您不再需要此活动，因为片段将以内嵌方式显示。所以你可以完成活动

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) {
        // we are in landscape so you do not need this activity anymore
        finish();
        return;
    }

    if (savedInstanceState == null) {
         // plugin right pane fragment
         YourFragment frgm = new YourFragment();
         getSupportFragmentManager().beginTransaction()
                .add(..., frgm).commit();
    }
}

碎片和方向改变

7 个答案: