Question

我的问题是Bundle bundle=getArgument();为空。

我尝试ActivitySerializable activitySerializableTest=(ActivitySerializable)bundle.getSerializable("activitySerializable");也是空的。

当我的布局是片段时，如何从Object获取值？

非常感谢任何帮助。

My Serializable calss是这样的：

    public class ActivitySerializable implements Serializable {
      private String EDUTITLE;

      public String getEDUTITLE() {
            return EDUTITLE;
        }

      public void setEDUTITLE(String EDUTITLE) {
            this.EDUTITLE = EDUTITLE;
        }
}

我的A片段尝试设置如下值：

    public class ActivityListDomesticFragment extends Fragment{

    .......

    @Override
        public void onActivityCreated(@Nullable Bundle savedInstanceState) {
            super.onActivityCreated(savedInstanceState);

            ActivitySerializable activitySerializable=new ActivitySerializable();

            activitySerializable.setEDUTITLE("Value");

            //set the Bundle

            ActivityContents activityContentsFragment=new ActivityContents();//i want to get value from this fragment

            Bundle serializableBundle=new Bundle();


            serializableBundle.putSerializable("activitySerializable",activitySerializable);


            activityContentsFragment.setArguments(serializableBundle);//send bundle

            switchFragment(activityHomePage);//switch to next Fragment
    }
//change fragment function
private void switchFragment(Fragment fragment) {
    FragmentManager manager = getActivity().getSupportFragmentManager();
    FragmentTransaction transaction = manager.beginTransaction();
    transaction.replace(R.id.mainFrame, fragment, null);
    transaction.addToBackStack(null);
    transaction.commit();
}

我的B片段获得如下值：

public class ActivityContents extends Fragment{
    @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View view = inflater.inflate(R.layout.activity_contents_fragment, container, false);


            Bundle bundle = getArguments();
            // it shows my activitySerializableTest is on a null object reference
            ActivitySerializable activitySerializableTest=(ActivitySerializable)bundle.getSerializable("activitySerializable");

                    String test=activitySerializableTest.getEDUIN();
                    activityCtEduin.setText(test);
                    if (bundle != null) {
                    String EDUTITLE=activitySerializable.getEDUTITLE();
                        activityCtTitle.setText(EDUTITLE);
            else{
               //bundle is null
            }
            return view;
        }
}

通过单击MainActivity抽屉项目更改为ActivityContents。这是它的布局：

    <android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:id="@+id/drawerLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.example.user.taiwandigestionsociety_v11.MainActivity">


        <android.support.design.widget.AppBarLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#FFFFFF">


    <include layout="@layout/toolbar"/>

//fragment change over here-------------------------------------
            <FrameLayout
                android:id="@+id/mainFrame"
                android:layout_gravity="end"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

            </FrameLayout>

        </android.support.design.widget.AppBarLayout>


        <android.support.design.widget.NavigationView
            android:id="@+id/nav_view"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_gravity="start"
            android:background="@android:color/transparent"
            android:fitsSystemWindows="true"
            app:headerLayout="@layout/nav_header">
        </android.support.design.widget.NavigationView>


    </android.support.v4.widget.DrawerLayout>

我关于更改片段的主要活动：

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
.......

@Override
    public void onClick(View view) {
if (id == R.id.activitiesContents) {
            //here is change to ActivityContents fragment
            switchFragment(ActivityContents.newInstance());
            drawerLayout.closeDrawer(GravityCompat.START);
        }
}

Answer 1

Fragment不应将getArguments作为字段的初始化程序。从生命周期回调中调用它，例如onCreateView。在创建对象时，尚未设置参数，因此当前代码将始终返回null。

您还应该考虑使用Parcelable代替Serializable，因为它更有效。此外，如果您的参数是基元或字符串，则无需使用Serializable或Parcelable，Bundle将直接处理基本类型和字符串。

Answer 2

我找到一个解决方案来保存我的问题，它是关于单身人士：

我将它用于我的Book类，如下所示：

public static Book book=null;

    public static Book getBook(){
        if (book==null){
            book=new Book();
            return book;
        }else {
            return book;
        }
    }

在A：

Book book=Book.getBook();
book.setName("Jerry");

在C：

Book book=Book.getBook();
textView.setText(book.getName());

然后我的问题结束了，我必须放弃Serializable。

如何在Serializable中将Object数据从片段传递到片段？

2 个答案: