将数据从 Fragment 传递到新 Activity

Question

我正在尝试将数据从我的 Main Activity 传递给我的 Camera Activity，再传递给我的 Camera Fragment，然后再传回我的 Main Activity。我希望用户能够保存他们在 Main Activity 上输入的信息，以便在他们使用完相机后保留下来。

在我的 Main Activity 上，我将以下内容作为 Intent Extras 传递给 Camera Activity：

（注意：这可行）

Intent cameraIntent = new Intent(MainActivity.this, CameraActivity.class);
    cameraIntent.putExtra("description" , editTextDescription.getText().toString());
    cameraIntent.putExtra("category" , editTextCategory.getText().toString());
    cameraIntent.putExtra("notes" , editTextNotes.getText().toString());
MainActivity.this.startActivity(cameraIntent);

然后，我将成功接收 Camera Activity 上的附加内容，并将它们打包传递给我的 Camera Fragment：

（注意：这可行）

Intent intent = getIntent();

if (intent.getExtras() != null) {

     description = intent.getExtras().getString("description");
     category = intent.getExtras().getString("category");
     notes = intent.getExtras().getString("notes");

    }

if (null == savedInstanceState) {

    CameraFragment cameraFragment = new CameraFragment();

    Bundle bundle = new Bundle();

    bundle.putString("description", description);
    bundle.putString("category", category);
    bundle.putString("notes", notes);
    cameraFragment.setArguments(bundle);

    Log.v(TAG, "Here is the bundle: " + bundle.toString());

    getFragmentManager().beginTransaction()
        .replace(R.id.container, cameraFragment.newInstance())
        .add(cameraFragment, bundle.toString())
        .commit();

    }

在我的 Camera Fragment 中，我收到了 onCreateView 中的捆绑包，如下所示：

（注意：这可行）

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    if (getArguments() != null) {

        description = getArguments().getString("description");
        category = getArguments().getString("category");
        notes = getArguments().getString("notes");
        Log.v(TAG, "Here are your arguments from the camera activity:  " + description + "  " + category + "  " + notes);

    } 

    else {
        Log.v(TAG, "Your arguments are null");
    }

    return inflater.inflate(R.layout.fragment_camera, container, false);
}

所有这些交易都在正确执行，到目前为止，我已正确收到所有信息。我现在的目标是获取信息，并将其传递回 Main Activity。

问题**

case R.id.doneButton: {

    Intent intent = new Intent(getActivity(), MainActivity.class);
            intent.putExtra("description", description);
            intent.putExtra("category", category);
            intent.putExtra("notes", notes);
            Log.v(TAG, "Here are the extras going back to the Main Activity " + description + "  " + category + "  " + notes);
    startActivity(intent);
            break;

        }

但是，我无法获取我在 Fragment 中收到的信息，并在其他地方使用变量。我试图尝试在 onCreateView 以外的方法中获取参数，然后在将附加内容传递回 Main Activity 之前使用该方法。我也尝试在我的 onClick 开关、case 方法中获取参数，但是，当我尝试将数据发送回我的 Main Activity 时，它总是返回 null，因为它没有采用它在参数中收到的内容，而是使用我之前声明的字符串。

private String description;
private String category;
private String notes;

有没有办法获取我在 Camera Fragment 的参数中收到的数据，并在 onCreateView 方法之外使用它们，然后将它们发送回我的主要活动？

Answer 1

为什么不在 Fragment 中创建一个“get”方法。

cameraFragment.getXXXX();

Answer 2

我已经重写了你的代码，这很有效。

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Intent cameraIntent = new Intent(MainActivity.this, CameraActivity.class);
        cameraIntent.putExtra("description" , "description");
        cameraIntent.putExtra("category" , "category");
        cameraIntent.putExtra("notes" , "notes");
        startActivity(cameraIntent);
    }
}

public class CameraActivity extends Activity{

    private String description,category,notes;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera);
        Intent intent = getIntent();

        if (intent.getExtras() != null) {

            description = intent.getExtras().getString("description");
            category = intent.getExtras().getString("category");
            notes = intent.getExtras().getString("notes");

        }

        if (null == savedInstanceState) {

            CameraFragment cameraFragment = new CameraFragment();

            Bundle bundle = new Bundle();

            bundle.putString("description", description);
            bundle.putString("category", category);
            bundle.putString("notes", notes);
            cameraFragment.setArguments(bundle);

            Log.v(TAG, "Here is the bundle: " + bundle.toString());

            getFragmentManager().beginTransaction()
                    .replace(R.id.container, cameraFragment)
                    .commit();

        }
    }
}

即使在 doneButton 的 onClick 中，也会填充 3 个字符串

public class CameraFragment extends Fragment{

    private String description,category,notes;
    private Button doneButton;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_camera, container, false);
        if (getArguments() != null) {

            description = getArguments().getString("description");
            category = getArguments().getString("category");
            notes = getArguments().getString("notes");
            Log.v("CameraFragment", "Here are your arguments from the camera activity:  " + description + "  " + category + "  " + notes);

        }

        else {
            Log.v("CameraFragment", "Your arguments are null");
        }
        doneButton = view.findViewById(R.id.doneButton);
        doneButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(getActivity(), MainActivity.class);
                intent.putExtra("description", description);
                intent.putExtra("category", category);
                intent.putExtra("notes", notes);
                Log.v("CameraFragment", "Here are the extras going back to the Main Activity " + description + "  " + category + "  " + notes);
                startActivity(intent);
            }
        });
        return view;
    }

}