Android:像带 fragment 的 Activity 一样的向导

Question

你好。

我在这里和其他网站上读了很多书，但似乎没有人有像应用程序一样使用 fragment 作为向导的可行解决方案。

我尝试实现一个，但目前遇到了一些问题。

这是带有 Step-Fragments 占位符的 Activity XML:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"
  android:layout_width="match_parent"
  android:layout_height="match_parent" >

  <FrameLayout
    android:id="@+id/fragment_container"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_above="@+id/cmd_previous"
    android:layout_alignParentTop="true" >
  </FrameLayout>

  <Button
    android:id="@+id/cmd_previous"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"
    android:layout_alignRight="@+id/center_separator_buttons"
    android:text="@string/rpz_cmd_perv" />

  <View
    android:id="@+id/center_separator_buttons"
    style="@style/wd_center_aligner"
    android:layout_alignParentBottom="true" />

  <Button
    android:id="@+id/cmd_next"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/center_separator_buttons"
    android:layout_alignParentBottom="true"
    android:layout_alignParentRight="true"
    android:text="@string/rpz_cmd_next" />

</RelativeLayout>

在 OnCreate 中，我将第一步添加到 Activity 中:

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

  if (this.getIntent().getExtras() != null) {
    Bundle extra = this.getIntent().getExtras();
    if (extra.containsKey(ISelected.ID_KEY)) {
      _ID = extra.getLong(ISelected.ID_KEY);
    }
  }

  if (findViewById(R.id.fragment_container) != null && savedInstanceState == null) {
    _ReportTypeAndName = new ReportWizardTypeAndNameFragment();
    _ReportTypeAndName.setArguments(getIntent().getExtras());
    getSupportFragmentManager().beginTransaction().add(R.id.fragment_container, _ReportTypeAndName).commit();
  }
}

NEXT 按钮用新 fragment 替换当前 fragment 。这似乎工作正常。

private void runNext(View view) {
  switch (_CurrentPage) {
    case ReportTypeAndName:
      _ReportSelect = new ReportWizardSelectFragment();
      _ReportSelect.setArguments(getIntent().getExtras());
      getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, _ReportSelect).addToBackStack(null).commit();

      _CurrentPage = ReportWizardPage.ReportSelect;
      break;

    case ReportSelect:
      _CurrentPage = ReportWizardPage.ReportPreview;
      break;

    case ReportPreview:
      _CurrentPage = ReportWizardPage.None;
      break;

    default:
      break;
  }
}

但是在 PREVIOUS 按钮上，这不起作用。

private void runPrevious(View view) {
  switch (_CurrentPage) {
    case ReportTypeAndName:
      // Umstellung des Typs
      _CurrentPage = ReportWizardPage.None;
      this.finish();
      break;

    case ReportSelect:
      _ReportTypeAndName = new ReportWizardTypeAndNameFragment();
      _ReportTypeAndName.setArguments(getIntent().getExtras());
      getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, _ReportTypeAndName).commit();

      _CurrentPage = ReportWizardPage.ReportTypeAndName;
      break;

    case ReportPreview:
      _CurrentPage = ReportWizardPage.ReportSelect;
      break;

    default:
      break;
  }
}

我收到以下错误 (LogCat):

FATAL EXCEPTION: main
android.view.InflateException: Binary XML file line #13: Error inflating class fragment
  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:697)
  at android.view.LayoutInflater.rInflate(LayoutInflater.java:739)
  at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
  at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
  at de.webducer.android.worktime.beta.ui.fragment.ReportWizardTypeAndNameFragment.onCreateView(ReportWizardTypeAndNameFragment.java:40)
  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:870)
  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1080)
  at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:622)
  at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1416)
  at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:420)
  at android.os.Handler.handleCallback(Handler.java:605)
  at android.os.Handler.dispatchMessage(Handler.java:92)
  at android.os.Looper.loop(Looper.java:137)
  at android.app.ActivityThread.main(ActivityThread.java:4424)
  at java.lang.reflect.Method.invokeNative(Native Method)
  at java.lang.reflect.Method.invoke(Method.java:511)
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
  at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalArgumentException: Binary XML file line #13: Duplicate id 0x7f05008b, tag null, or parent id 0x0 with another fragment for de.webducer.android.worktime.beta.ui.fragment.ReportTypeSelectorSpinnerFragment
  at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:275)
  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:669)
  ... 18 more

Fragment 的第 40 行是它们的充气器

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
  return inflater.inflate(R.layout.frag_report_wizard_1, container, false);
}

如何绑定(bind)(添加/删除) fragment 而不获取重复 ID？或者如何在没有新 View 初始化的情况下重用 fragment ？

Answer 1

将你的 fragment 放在后台栈中，并在需要时调用它们。

使用addToBackStack将它添加到backstack:

list = new ListFragment_List();
getFragmentManager().beginTransaction().replace(R.id.pane, listlist).addToBackStack(null).commit();

使用 popBackStack 将其拉回:

FragmentManager fm = getActivity().getSupportFragmentManager();
fm.popBackStack();

请注意，此代码来 self 的一个使用 v4 支持库的应用程序，因此如果您仅针对 Android 3.0+ 进行开发，则对 fragment 管理器的调用会略有不同。