java - 如何在监听器中正确使用 bundle (匿名内部类)

Question

我正在创建的应用程序有问题。
我在一个主 Activity 中创建了一系列 fragment 。
在每个 Fragment 中，要么是一个用于数据收集的表单，要么是一个用于显示收集到的数据的 ListView。

数据操作由几个小部件的监听器方法和幕后的数据模型控制。

基本上，我使用数据收集 fragment 将数据存储在 SQLite 数据库中，然后在前往显示 fragment 时对其进行查询。显示 fragment 具有用于返回集合 fragment 以添加、编辑或删除选定项目的按钮。在按下添加/编辑按钮的情况下，我会在某些状态下发送一个 bundle ，该 bundle 可以根据用户的需要进行不同的填充。通常，一个包包含从父上下文发送到子上下文的信息，子上下文在该子上下文上解包包并将数据放置在文本字段中和/或设置包含静态数据的微调器。

我尝试使用一种过于复杂的方法，直接在正在使用的任何小部件监听器中创建一个新的 Bundle。
但我发现它在以下 fragment 中创建了不必要的复杂性，我需要测试来自几个不同可能来源的 bundle 中包含的键。

我的想法是在我会调用的任何 Fragment 的开头
Bundle bundle = this.getArguments()
这将设置 bundle传递给传入的任何 Bundle:
fragment.setArguments(*bundle based on conditions*)
因此，从这个流程中，我必须创建一个非常长且难以阅读的 if 条件序列，以查找基于 bundle.isEmpty() 的特定键。如果您是第一次到达该 Fragment 并且尚未发送任何包，那么这当然会引发 NullPointerException。
然后为了使噩梦更加复杂，我将所有这些都放入了 try-catch 中以处理 bundle.isEmpty() 空指针，我试图将其用作当前状态的指示器(/sigh ...我知道)。

我想做的是使用 Bundle savedInstanceState对于任何信息/状态流量到一个新的 fragment 。
所以理想情况下，我只需要访问一个 Bundle 并测试包含 key 。
那么看来我可以测试是否savedInstanceState为空并以某种方式设置它。

问题是我的 fragment 中有这些小部件，我用它们来与我的模型交互并可能导航到下一个必要的 fragment 。
如果我使用 savedInstanceState在 onClick 内其中一个小部件的监听器方法，我被迫使其 final这立即使我无法使用 savedInstanceState在任何其他范围内，但它的初始用法或至少这是我的理解。
当我尝试访问 savedInstanceState 时，这会导致 NullPointerException 错误在第一个范围之外。

如果我删除 final IDE 告诉我(正确地)我无法访问 savedInstanceState从内部类中，在我的例子中是几个小部件，我附加了监听器方法。

我读过了:

Are the bundles in android permanent in saving activity states ?

How to use the anonymous inner class?

How to use Outer Method's input in Anonymous Inner Class?

这是两个依赖于相互发送 Bundle 的 Fragment 的代码示例；

显示和选择类:

public class Row_main extends Fragment {

Spinner location_spinner;
Button add_row_btn,edit_row_button,delete_row_btn;

ListView row_list_holder;

StorageHandler sh;
List<Row> row_list;

ArrayAdapter<CharSequence> ls_adapter;
String [] location_test_values = {"test_location"};


boolean has_items;

public Row_main()
{
    //default constructor
}

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


    if(savedInstanceState == null)
    {
        //this will satisfy if arriving here from navigation menu.
        //I would like to set savedInstanceState here if null.
        savedInstanceState = new Bundle();
        //but I get error: 'cannot assign a value to final variable'
    }

    getActionBar().setTitle("Row");

    //Create view
    final View v = inflater.inflate(R.layout.row_main_layout, container, false);

    add_row_btn = (Button) v.findViewById(R.id.add_row_btn);
    edit_row_button = (Button) v.findViewById(R.id.edit_row_btn);
    delete_row_btn = (Button) v.findViewById(R.id.delete_row_btn);

    add_row_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            addRow fragment = new addRow();

            FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
            fragment.setArguments(savedInstanceState);
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();

            getActionBar().setTitle("Add Row");
        }
    });

    edit_row_button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            for(int i=0; i<row_list.size(); i++)
            {
                if(row_list.get(i).isSelected())
                {
                    row_list.get(i).setEdited(true);

                    addRow fragment = new addRow();

                    savedInstanceState.putStringArrayList("current_row",row_list.get(i).getList());

                    fragment.setArguments(savedInstanceState);

                    FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
                    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
                    fragmentTransaction.replace(R.id.fragment_container, fragment);
                    fragmentTransaction.addToBackStack(null);
                    fragmentTransaction.commit();
                    getActionBar().setTitle("Add Row");
                }
            }
        }
    });

    return v;
}

private ActionBar getActionBar() {
    return ((AppCompatActivity) getActivity()).getSupportActionBar();
}

这是数据收集表单类:

public class addRow extends Fragment {

IdGenerator generator;

String new_id;

AlertDialog.Builder alertDialogBuilder, fmdDialogBuilder;

EditText row_name,
         rack_name,
         tile_location,
         tile_name,
         separation,
         bf_offset;

Spinner object_type,
        direction,
        rotation;

ArrayAdapter<CharSequence> objType_adapter,
                     direction_adapter,
                     rotation_adapter;

String[] objtype_values = {"Rack","FMD"};
String[] direction_values = {"Right","Left"};
String[] rotation_values = {"0","90","180","270"};

int RACK = 0,FMD = 1,RIGHT = 0,LEFT = 1;

Row current_row;

ArrayList<String> list_to_unpack;

Button  save_row_btn,
        add_btn,
        cancel_btn;

public addRow() {
    // Required empty public constructor
}


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

    generator = new IdGenerator();
    new_id = generator.randomString(5);

    if(savedInstanceState != null)
    {
        //Bundle passed, edit button was used, unpack
        if (savedInstanceState.containsKey("current_row")) {
            Log.d("BUNDLE-CONTENTS", "" + savedInstanceState.size());

            list_to_unpack = savedInstanceState.getStringArrayList("current_row");

            current_row.setId(list_to_unpack.get(0));
            current_row.setRow_name(list_to_unpack.get(1));
            current_row.setObject_type(list_to_unpack.get(2));
            current_row.setRack_name(list_to_unpack.get(3));
            current_row.setTile_location(list_to_unpack.get(4));
            current_row.setTile_name(list_to_unpack.get(5));
            current_row.setDirection(list_to_unpack.get(6));
            current_row.setRotation(list_to_unpack.get(7));
            current_row.setSeparation(list_to_unpack.get(8));
            current_row.setBf_offset(list_to_unpack.get(9));
            current_row.setEdited(true);

            row_name.setText(current_row.getRow_name());

            if (current_row.getObject_type().equalsIgnoreCase("Rack")) {
                object_type.setSelection(RACK);
            } else {
                object_type.setSelection(FMD);
            }

            rack_name.setText(current_row.getRack_name());

            tile_location.setText(current_row.getTile_location());

            tile_name.setText(current_row.getTile_name());

            if (current_row.getDirection().equalsIgnoreCase("Right")) {
                direction.setSelection(RIGHT);
            } else {
                direction.setSelection(LEFT);
            }

            switch(current_row.getRotation())
            {
                case "0": rotation.setSelection(0); break;
                case "90": rotation.setSelection(1); break;
                case "180": rotation.setSelection(2); break;
                case "270": rotation.setSelection(3); break;
            }

            separation.setText(current_row.getSeparation());

            bf_offset.setText(current_row.getBf_offset());
        }
    }

    row_name = (EditText) v.findViewById(R.id.rowName_value);
    rack_name = (EditText) v.findViewById(R.id.rackName_value);
    tile_location = (EditText) v.findViewById(R.id.tileLoc_value);
    tile_name = (EditText) v.findViewById(R.id.tileName_value);
    separation = (EditText) v.findViewById(R.id.separation_value);
    bf_offset = (EditText) v.findViewById(R.id.bfOffset_value);

    object_type = (Spinner) v.findViewById(R.id.obj_type);
    direction = (Spinner) v.findViewById(R.id.direction);
    rotation = (Spinner) v.findViewById(R.id.rotation_spinner);

    objType_adapter = new ArrayAdapter<CharSequence>(this.getActivity(),
            android.R.layout.simple_spinner_dropdown_item, objtype_values);
    direction_adapter = new ArrayAdapter<CharSequence>(this.getActivity(),
            android.R.layout.simple_spinner_dropdown_item, direction_values);
    rotation_adapter = new ArrayAdapter<CharSequence>(this.getActivity(),
            android.R.layout.simple_spinner_dropdown_item, rotation_values);

    object_type.setAdapter(objType_adapter);
    direction.setAdapter(direction_adapter);
    rotation.setAdapter(rotation_adapter);

    save_row_btn = (Button) v.findViewById(R.id.save_row_btn);
    add_btn = (Button) v.findViewById(R.id.add_btn);
    cancel_btn = (Button) v.findViewById(R.id.cancel_btn);

    alertDialogBuilder = new AlertDialog.Builder(getActivity());
    fmdDialogBuilder = new AlertDialog.Builder(getActivity());

    alertDialogBuilder.setMessage("Add Rack or FMD:");
    fmdDialogBuilder.setMessage("Add Power Providing or Power Consuming FMD:");

    alertDialogBuilder.setNegativeButton("Rack", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            //if user selects power providing fmd
            //send id with it
            //StorageHandler sh = new StorageHandler(getActivity());

            Row row = new Row(
                    new_id,
                    row_name.getText().toString(),
                    object_type.getSelectedItem().toString(),
                    rack_name.getText().toString(),
                    tile_location.getText().toString(),
                    tile_name.getText().toString(),
                    direction.getSelectedItem().toString(),
                    rotation.getSelectedItem().toString(),
                    separation.getText().toString(),
                    bf_offset.getText().toString());



            ArrayList<String> rowList = row.getList();

            for(String i : rowList)
            {
                Log.d("ADD ROW BTN","rowList[i]=" + i);
            }

            savedInstanceState.putStringArrayList("current_row", rowList);

            addRack fragment = new addRack();
            fragment.setArguments(savedInstanceState);
            FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();
            getActionBar().setTitle("Add Rack to: " + row.getRow_name());
        }
    });

    alertDialogBuilder.setPositiveButton("FMD", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            //todo choice between consuming and providing
            fmdDialogBuilder.show();
        }
    });

    fmdDialogBuilder.setPositiveButton("Providing", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {

            Row row = new Row(
                    new_id,
                    row_name.getText().toString(),
                    object_type.getSelectedItem().toString(),
                    rack_name.getText().toString(),
                    tile_location.getText().toString(),
                    tile_name.getText().toString(),
                    direction.getSelectedItem().toString(),
                    rotation.getSelectedItem().toString(),
                    separation.getText().toString(),
                    bf_offset.getText().toString());

            ArrayList<String> obj_as_list = row.getList();

            Log.d("newId", obj_as_list.get(0));
            Log.d("row_name", obj_as_list.get(1));
            Log.d("object_type", obj_as_list.get(2));
            Log.d("rack_name", obj_as_list.get(3));
            Log.d("objaslistsize", ""+obj_as_list.size());

            savedInstanceState.putStringArrayList("current_row", obj_as_list);

            addPowerProvidingFMD fragment = new addPowerProvidingFMD();

            fragment.setArguments(savedInstanceState);
            FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();
            getActionBar().setTitle("add FMD to: " + row_name.getText().toString());
        }
    });

    fmdDialogBuilder.setNegativeButton("Consuming", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {

            Row row = new Row(
                    new_id,
                    row_name.getText().toString(),
                    object_type.getSelectedItem().toString(),
                    rack_name.getText().toString(),
                    tile_location.getText().toString(),
                    tile_name.getText().toString(),
                    direction.getSelectedItem().toString(),
                    rotation.getSelectedItem().toString(),
                    separation.getText().toString(),
                    bf_offset.getText().toString());

            ArrayList<String> obj_as_list = row.getList();

            savedInstanceState.putStringArrayList("current_row", obj_as_list);

            addPowerConsumingFMD fragment = new addPowerConsumingFMD();
            fragment.setArguments(savedInstanceState);
            FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();
            getActionBar().setTitle("add FMD to: " + row_name.getText().toString());
        }
    });

    save_row_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //save row info to database
            StorageHandler sh = new StorageHandler(getActivity());

            if(current_row.isEdited())
            {
                //update row
                String current_id = current_row.getId();
                Log.d("*update row*", "id=" + current_id);

                //get updated values from fields, send to database
                Row row = new Row(current_id, row_name.getText().toString(), object_type.getSelectedItem().toString(),
                        rack_name.getText().toString(), tile_location.getText().toString(),
                        tile_name.getText().toString(), direction.getSelectedItem().toString(),
                        rotation.getSelectedItem().toString(), separation.getText().toString(),
                        bf_offset.getText().toString());

                sh.updateRow(row);

                sh.close();
            }
            else
            {
                //save new row
                Log.d("*save row*", "id=" + new_id);

                //save row to database
                sh.addRow(new Row(new_id, row_name.getText().toString(), object_type.getSelectedItem().toString(),
                        rack_name.getText().toString(), tile_location.getText().toString(),
                        tile_name.getText().toString(), direction.getSelectedItem().toString(),
                        rotation.getSelectedItem().toString(), separation.getText().toString(),
                        bf_offset.getText().toString()));

                sh.close();
            }

            Row_main fragment = new Row_main();
            FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();
            getActionBar().setTitle("Row");
        }
    });

    add_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
             alertDialogBuilder.show();
        }
    });

    cancel_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Row_main fragment = new Row_main();
            FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();
            getActionBar().setTitle("Row");
        }
    });

    return v;
}

private ActionBar getActionBar() {
    return ((AppCompatActivity) getActivity()).getSupportActionBar();
}

我想在这里使用 bundle ，因为如果用户离开应用程序或按下后退按钮，从 bundle 中恢复任何内容并不重要。

我这样做对吗？ onClickListener 中的最终 Bundle 情况我该怎么办？方法？我绝对需要按照我现在设置的方式从他们那里传递 bundle ，如果可以的话，我想使用相同的 bundle 。

我有一个要考虑的最后期限，所以彻底检修可能是不可能的。

非常感谢任何输入。

Answer 1

我认为一旦你重构了一些代码，隔离你的数据传递问题会更容易。

1. 用方法替换这些类似的 block 。您似乎已经将同样的代码复制了大约五次。

让它成为一种方法!调用 getRow() ，如果必须的话，给它一个参数，比如 int id .

// int id = <some_value>;

return new Row(id, row_name.getText().toString(), object_type.getSelectedItem().toString(),
        rack_name.getText().toString(), tile_location.getText().toString(),
        tile_name.getText().toString(), direction.getSelectedItem().toString(),
        rotation.getSelectedItem().toString(), separation.getText().toString(),
        bf_offset.getText().toString());

2. 现在，您似乎正在绕过这个 Row类，所以建议做 implement Parcelable 这样您就可以更轻松地在 Bundle 之间传递s 需要时。

3. 接下来，您应该 let the Fragment interactions happen across the Activity boundary ，而不是来自每个 fragment 内。因此，例如，您添加接口(interface)。如果您不需要所有这些功能，您可以将其拆分为许多接口(interface)。

public interface OnRowInteractionListener {
    public void onRowAdded(Row row);
    public void onRowEdited(Row row);
    public void onRowRemoved(Row row);
    public void onRowActionCancel();
}

3a。 实现 onAttach Fragment 类来设置这些接口(interface)。

private OnRowInteractionListener mListener;

@Override
public void onAttach(Context context) {
    super.onAttach(context);
    final String contextName = context.class.getSimpleName();
    try {
        mListener = (OnRowInteractionListener) context;
    } catch (ClassCastException e) {
        throw new ClassCastException(contextName + " must implement OnRowInteractionListener");
    }
}

3b。 现在，清理 Fragment 按钮

add_row_btn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Row added = getRow(); // remember about that parameter value
        if (mListener != null) mListener.onRowAdded(added);
    }
});

3c。 在Activity中，你需要在创建类 implements OnRowInteractionListener之后实现这些接口(interface)。 .

@Override
public void onRowAdded(Row row) { 

    getActionBar().setTitle("Add Row");

    // This acts like your 'constructor'
    AddRowFragment fragment = AddRowFragment.newInstance(row);
    // fragment.setArguments(savedInstanceState);

    getSupportFragmentManager()
            .beginTransaction()
            .replace(R.id.fragment_container, fragment)
            .addToBackStack(null)
            .commit();
}

(与 onRowEdited 类似)

4. 我还看到这个 fragment 替换代码块对取消和保存按钮重复，所以也把它作为一个方法。

Row_main fragment = new Row_main();
FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
getActionBar().setTitle("Row");

我真的建议您在 Activity 中创建一个非常通用的方法来处理所有 fragment 转换。

public void transitionFragment(Fragment fragment, Bundle arguments, String title) { 

    getSupportActionBar().setTitle(title);

    if (arguments != null) fragment.setArguments(arguments);

    getSupportFragmentManager()
            .beginTransaction()
            .replace(R.id.fragment_container, fragment)
            .addToBackStack(null)
            .commit();
}

然后，只需传入相应的 newInstance() 'd Fragment 到该方法，只要你需要它。可选地传递额外的参数，否则，只是 null .

因此，您现在可以在前面的代码块中使用该方法，例如，在接口(interface)实现的取消操作中。

@Override
public void onRowActionCancel() {
    Fragment fragment = RowMainFragment.newInstance();
    transitionFragment(fragment, null, "Add Row");
}

就 SQLite 处理而言，可以查看 RealmDB、SugarORM 或任何 ORM 库。
findViewById可以使用 Butterknife 简化代码。此外， Android Data Binding library如果您经常将数据从 Java 对象映射到 View 对象。