如何在片段中使用 Parcelable 获取数据？

Posted 2023-04-15

【中文标题】如何在片段中使用 Parcelable 获取数据？

【英文标题】：How to use Parcelable in fragment for getting data?

【发布时间】：2016-02-12 06:12:55

【问题描述】：

我可以在 Activity 中使用 Parcelable 但我不知道如何在 Fragment 中使用它。

我在 FragmentGet 中有一个 ListFragment 用于在 ListView 中显示所有行数据库，我想在单击另一个 Fragment 时获取 ListView 的详细信息，我使用 Parcelable 在 Fragment 之间传递数据。

这是我的 Test.java：

import android.os.Parcel;
import android.os.Parcelable;

public class Test implements Parcelable 

    private int studentNumber;
    private String studentName;
    private String studentFamily;

    public int getStudentNumber() 
        return studentNumber;
    

    public void setStudentNumber(int studentNumber) 
        this.studentNumber = studentNumber;
    

    public String getStudentName() 
        return studentName;
    

    public void setStudentName(String studentName) 
        this.studentName = studentName;
    

    public String getStudentFamily() 
        return studentFamily;
    

    public void setStudentFamily(String studentFamily) 
        this.studentFamily = studentFamily;
    

    public Test() 
    

    public Test(Parcel read) 
        studentNumber = read.readInt();
        studentName = read.readString();
        studentFamily = read.readString();
    

    @Override
    public int describeContents() 
        return 0;
    

    @Override
    public void writeToParcel(Parcel write, int flags) 
        write.writeInt(studentNumber);
        write.writeString(studentName);
        write.writeString(studentFamily);
    

    public static final Parcelable.Creator<Test> CREATOR =
            new Parcelable.Creator<Test>() 
                @Override
                public Test createFromParcel(Parcel source) 
                    return new TestP(source);
                
                @Override
                public Test[] newArray(int size) 
                    return new TestP[size];
                
            ;

在 FragmentSend.java 中我想向 FragmentGet.java 发送数据，代码如下：

public class FragmentSend extends ListFragment 

    //    Classes
    TestReadData readData;
    TestDataSource dataSource;

    private List<Test> listTest;       

    public FragmentSend() 
        // Required empty public constructor
    


    @TargetApi(Build.VERSION_CODES.M)
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) 

        View layout = inflater.inflate(R.layout.fragment_send, container, false);

        readData = new TestReadData(getContext());
        dataSource = new TestDataSource(getContext());  

       refreshStudentList(inflater);

    return layout;


public void refreshStudentList(LayoutInflater inflater) 

    listTest = readData.getAllStudentRows();
    ArrayAdapter<Test> testAdapter = new TestFragmentListAdapter(inflater.getContext(), listTest);
    setListAdapter(testAdapter);



    @Override
    public void onResume() 
        super.onResume();
        dataSource.open();
    

    @Override
    public void onPause() 
        super.onPause();
        dataSource.close();
    

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) 
        super.onListItemClick(l, v, position, id);

        Test model = listTest.get(position);

        // this three line code is for Activity not Fragment!
        Intent intent = new Intent(getContext(), FragmentGet.class);
        intent.putExtra("Student", model);
       // startActivity(intent);

        // I use this code for fragment
        Fragment fragmentGet = new FragmentGet();
    fragmentGet.setArguments(intent.getExtras());
    FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    fragmentTransaction.replace(R.id.frame_container, fragmentGet);
    fragmentTransaction.addToBackStack(null);
    fragmentTransaction.commit();

    

在 FragmentGet.java 我得到这样的数据：

public class FragmentGet extends Fragment 

    //    Classes
    Test model;    

    //    Variables
    private List<Test> listTest;

    public FragmentGet () 
        // Required empty public constructor
    


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) 
        // Inflate the layout for this fragment
        View layout = inflater.inflate(R.layout.fragment_get, container, false);

        //        Classes Associated
        model = new Test(Parcel.obtain());

        Bundle bundle = getActivity().getIntent().getExtras();
        model = bundle.getParcelable("Student");

        return layout;    
    

当我运行应用程序时，我会收到此错误：

尝试调用虚拟方法'android.os.Parcelable android.os.Bundle.getParcelable(java.lang.String)' 在一个空对象上 参考

我该如何解决这个错误？

【参考方案1】：

向Fragments 传递数据是使用Bundles 而不是Intents。

在FragmentSend改

Intent intent = new Intent(getContext(), FragmentGet.class);
intent.putExtra("Student", model);

Fragment fragmentGet = new FragmentGet();
fragmentGet.setArguments(intent.getExtras());

到这里

Fragment fragmentGet = new FragmentGet();
Bundle bundle = new Bundle();
bundle.putParcelable("Student", model);
fragmentGet.setArguments(bundle);

并接收FragmentGet中的数据变化

Bundle bundle = getActivity().getIntent().getExtras();
model = bundle.getParcelable("Student");

到

Bundle bundle = this.getArguments();
if (bundle != null) 
    model = bundle.getParcelable("Student");