java - 创建用户定义的Parcelable对象并实现功能

Question

Android 编程新手。我有 2 个必须可打包的对象，称为 Book 和 Author。我相当确定我准备得正确。我希望得到一些帮助:

• 创建一本书

• 将他们发送到新 Activity

  public class Book implements Parcelable {
  
  public int id;
  public String title;
  public ArrayList<Author> authors = new ArrayList<Author>();
  public int Aflags;
  public String isbn;
  public String price;
  
  @Override
  public int describeContents() {
      return 0;
  }
  
  @Override
  public void writeToParcel(Parcel out, int flags) {
      out.writeInt(id);
      out.writeString(title);
      out.writeTypedList(authors);
      out.writeString(isbn);
      out.writeString(price);
  }
  
  private Book(Parcel in) {
      id = in.readInt();
      title = in.readString();
      in.readTypedList(authors, Author.CREATOR);
      isbn = in.readString();
      price = in.readString();
  }
  
  
  public static final Parcelable.Creator<Book> CREATOR = new Parcelable.Creator<Book>() {
      public Book createFromParcel(Parcel in) {
          return new Book(in);
      }
      public Book[] newArray(int size) {
          return new Book[size];
      }
  };
  
  @Override
  public String toString()
  {
      return title + " Price: " + price;
  }
  
   }
  

  现在作者:

  public class Author implements Parcelable {
  
  // TODO Modify this to implement the Parcelable interface.
  // I think I was able to accomplish this
  // NOTE: middleInitial may be NULL!
  
  public String firstName;
  
  public String middleInitial;
  
  public String lastName;
  
  @Override
  public void writeToParcel(Parcel out, int flags) {
      out.writeString(firstName);
      if (middleInitial.length() == 0)
          out.writeString(middleInitial);
      out.writeString(lastName);
  }
  
  private Author(Parcel in)
  {
      firstName = in.readString();
      if (in.dataSize() > 2)
          middleInitial = in.readString();
      lastName = in.readString();
  }
  
  public static final Parcelable.Creator<Author> CREATOR = new Parcelable.Creator<Author>() {
      public Author createFromParcel(Parcel in) {
          return new Author(in);
      }
  
      public Author[] newArray(int size) {
          return new Author[size];
      }
  };
  
  @Override
  public int describeContents() {
      return 0;
  }
  
  
    }
  

我不知道为什么我被难住了，但我不知道如何实现我的 Parcel 来制作这本书并走得更远。这是尝试制作书籍然后将其发送到另一个 Activity 的 Activity :

public class AddBookActivity extends Activity {

// Use this as the key to return the book details as a Parcelable extra in the result intent.
public static final String BOOK_RESULT_KEY = "book_result";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.add_book);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    super.onCreateOptionsMenu(menu);
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.search_menu, menu);
    // COMPLETED TODO provider SEARCH and CANCEL options
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    super.onOptionsItemSelected(item);
    // TODO
    switch (item.getItemId()) {
    case R.id.search:
    // SEARCH: return the book details to the BookStore activity
        this.searchBook();
    return true;
    case R.id.cancel:
        new AlertDialog.Builder(this)
        .setTitle("Cancel Search")
        .setMessage("Are you sure you want to cancel your search?")
        .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) { 
                AddBookActivity.this.finish();
            }
         })
        .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) { 
                // do nothing
            }
         })
        .setIcon(R.drawable.ic_dialog_alert)
         .show();
    // CANCEL: cancel the search request
    return true;
    }
    return false;
}

public Book searchBook(){
    /*
     * Book object with the search criteria and return that.
    */
    EditText editText = (EditText) findViewById(R.id.search_title);
    String title = editText.getText().toString();
    editText = (EditText) findViewById(R.id.search_author);
    String author = editText.getText().toString();
    editText = (EditText) findViewById(R.id.search_isbn);
    int isbn = Integer.parseInt(editText.getText().toString());
    Parcel p = Parcel.obtain();
    p.writeInt(isbn);
    p.writeString(title);
    p.writeString(author);
    p.writeString(editText.getText().toString());
    p.writeString("$15.00");
    return null;
}

}

Answer 1

如果您尝试通过使用 Intent 将 Parcelable 对象发送到新 Activity，则应该像调用 Intentobject.putExtra("key", Parcelableobject) 一样简单。 Android 将为您处理剩下的事情，因为您的对象实现了 Parcelable 接口(interface)。