Question

我正在创建一个我正在创建的应用程序的问题我在一个主要的Activity中创建了一系列片段在每个片段中，可以是用于数据收集的表单，也可以是用于显示共享数据的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片段将数据存储在SQLite数据库中，然后在前往显示片段时查询该数据库。显示片段具有用于返回到集合片段以添加，编辑或删除所选项目的按钮。在添加/编辑按钮按下的情况下，我会在某些状态下发送一个可以根据用户的需要以不同方式填充的包。通常，bundle包含从父上下文发送到子上下文的信息，子上下文解压缩包并将数据放在文本字段中和/或设置包含静态数据的微调器。

我尝试使用过于复杂的方法，我在任何小部件监听器中直接创建了一个新的Bundle 但我发现它在下面的片段中创建了不必要的复杂性，我需要从几个不同的可能来源测试Bundles中包含的键。

我的想法是，在任何片段的开头，我会打电话给

Bundle bundle = this.getArguments()

将bundle设置为传入的Bundle：

fragment.setArguments(*bundle based on conditions*)

所以从这个流程开始，我不得不创建一个令人难以置信的长而难以阅读的if-conditionals继承基于bundle.isEmpty()查找特定键，当然如果你到达那个片段时会抛出NullPointerException第一次，还没有发送捆绑。
然后复制噩梦我在try-catch中抛出所有这些来处理bundle.isEmpty（）null指针，我试图用它作为当前状态的指示符（/叹息......我知道）。

我想要做的是将Bundle savedInstanceState用于任何信息/状态的流量到新的片段。
理想情况下，我只需要访问一个Bundle并测试包含密钥然后我似乎能够测试savedInstanceState是否为空并以某种方式设置它。

问题是我在片段中有这些小部件，我用它来与我的模型交互，并可能导航到下一个必要的片段。
如果我在其中一个小部件的savedInstanceState侦听器方法中使用onClick，我不得不将其final删除，这会立即消除我在任何其他范围内使用savedInstanceState的能力但最初使用它或至少是我的理解当我尝试访问第一个范围之外的savedInstanceState时，这会导致NullPointerException错误。

如果我删除final，IDE会告诉我（正确地说）我无法从内部类中访问savedInstanceState，在我的情况下，这是我附加了一些侦听器方法的小部件。< / p>

我读过：

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?

这是两个片段的代码示例，它们依赖于彼此发送Bundles;

显示并选择类：

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();
}

这里是数据收集表格类：

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Bundles，因为如果用户离开应用程序或按下后退按钮，从Bundle恢复任何内容并不重要。

我这样做了吗？我应该怎么做onClickListener方法中的最终Bundle情况？我绝对需要以现在设置的方式从他们那里传递Bundles，如果可以的话我想使用相同的Bundle。

我有一个考虑的最后期限，所以彻底改革可能是不可能的。

非常感谢任何输入。

Answer 1

我认为一旦重构某些代码，就会更容易隔离数据传递问题。

1。用方法替换这些类似的块。你似乎已经复制了大约五次相同的代码。

让它成为一种方法！称之为getRow()，如果必须，请为int id添加一个参数。

// 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，您似乎正在传递此Row课程，因此建议您使用implement Parcelable，以便您可以更轻松地在Bundle之间传递在需要时。

3。接下来，您应该let the Fragment interactions happen across the Activity boundary，而不是来自每个片段。因此，您可以添加接口。如果您不需要所有这些功能，可以将其拆分为多个接口。

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

3a。实现Fragment类的onAttach以设置这些接口。

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，清理片段按钮

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，您需要在创建类implements OnRowInteractionListener后实现这些接口。

@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();
}

（类似于onRowEdited）

4. 我也看到这个片段替换代码块重复了取消和保存按钮，所以也做一个方法。

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");

我真的建议你在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，只要您需要，就可以将相应的newInstance()＆＃f; d片段传递给该方法。可选择传递额外的参数，只需传递null。

那么，您现在可以将该方法用于上一个代码块，例如，在接口实现的取消操作中。

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

就SQLite处理而言，可能会查看RealmDB，SugarORM或任何ORM库。

使用Butterknife可以简化findViewById代码。此外，Android Data Binding library以防您经常将数据从Java对象映射到View对象。

如何在侦听器（匿名内部类）中正确使用Bundles

1 个答案: