Android

Question

我有一个 activity 来管理一些顺序片段的实例，还有一个 ViewPager，其适配器的类型为 FragmentStatePagerAdapter。这些片段是连续的，因为我想创建一种人们必须遵循的向导。一切正常，但如果用户未完成当前页面中的所有字段，我想在用户想要转到向导的下一页（片段）时禁用滑动。

    package edu.polimi.dima.home121;


import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.ActionBarActivity;

import edu.polimi.dima.home121.model.Place;

/**
 * Created by leo on 13/01/2015.
 */
public class NewPlaceActivity extends ActionBarActivity
        implements NewPlaceSummaryFragment.OnFragmentInteractionListener,
        NewPlaceWizardFirstStepFragment.OnFragmentInteractionListener,
        NewPlaceWizardSecondStepFragment.OnFragmentInteractionListener,
        NewPlaceWizardThirdStepFragment.OnFragmentInteractionListener,
        NewPlaceWizardFourthStepFragment.OnFragmentInteractionListener {

    private final String TAG = getClass().getSimpleName();
    private static Place place;

    private static final int NUM_PAGES = 7;
    private ViewPager mPager;
    private PagerAdapter mPagerAdapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        place = new Place();
        setContentView(R.layout.activity_new_place);

        mPager = (ViewPager) findViewById(R.id.pager);
        mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager(), mPager, place);
        mPager.setAdapter(mPagerAdapter);
        /*if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.newPlaceContainer, NewPlaceSummaryFragment.newInstance(place))
                    .commit();
        }*/
    }

    @Override
    public void onBackPressed() {
        if (mPager.getCurrentItem() == 0) {
            // If the user is currently looking at the first step, allow the system to handle the
            // Back button. This calls finish() on this activity and pops the back stack.
            super.onBackPressed();
        } else {
            // Otherwise, select the previous step.
            mPager.setCurrentItem(mPager.getCurrentItem() - 1);
        }
    }

    @Override
    public void onFragmentInteraction(Uri uri) {
    }

    private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
        private Place place;
        private ViewPager mPager;

        public ScreenSlidePagerAdapter(FragmentManager fm, ViewPager mPager, Place place) {
            super(fm);
            this.place = place;
            this.mPager = mPager;
        }

        @Override
        public Fragment getItem(int position) {
            switch (position) {
                case 0:
                    return new NewPlace0();
                case 1:
                    NewPlaceWizardFirstStepFragment f1 = new NewPlaceWizardFirstStepFragment().newInstance(place);
                    f1.setPager(mPager);
                    return f1;
                case 2:
                    NewPlaceWizardSecondStepFragment f2 = new NewPlaceWizardSecondStepFragment().newInstance(place);
                    f2.setPager(mPager);
                    return f2;
                case 3:
                    NewPlaceWizardThirdStepFragment f3 = new NewPlaceWizardThirdStepFragment().newInstance(place);
                    f3.setPager(mPager);
                    return f3;
                case 4:
                    NewPlaceWizardFourthStepFragment f4 = new NewPlaceWizardFourthStepFragment().newInstance(place);
                    f4.setPager(mPager);
                    return f4;
                case 5:
                    NewPlace99 f5 = new NewPlace99();
                    return f5;
                case 6:
                    NewPlaceSaving last = NewPlaceSaving.newInstance(place);
                    return last;
                default:
                    return null;
            }

        }

        @Override
        public int getCount() {
            //TODO sistemare il conteggio delle pagine
            return NUM_PAGES;
        }
    }
}

例如我的第一个片段是：

    public class NewPlaceWizardFirstStepFragment extends Fragment implements View.OnClickListener,
        DialogInterface.OnClickListener {

    private final String TAG = this.getClass().getSimpleName();

    private static Place place;
    private OnFragmentInteractionListener mListener;
    private static View view;
    private ViewPager pager;

    public NewPlaceWizardFirstStepFragment() {
    }

    private TextView lblAvailableFrom;
    private Button btnSingleRoom;
    private Button btnDoubleRoom;
    private Button btnStudioFlat;
    private Button btnApartment;
    private Button btnChangeDate;
    private Button btnNext;
    private EditText tfStreet;
    private EditText tfCivic;
    private EditText tfStair;
    private EditText tfFloor;
    private EditText tfCity;
    private EditText tfPostalCode;

    public static NewPlaceWizardFirstStepFragment newInstance(Place place) {
        NewPlaceWizardFirstStepFragment fragment = new NewPlaceWizardFirstStepFragment();
        fragment.place = place;
        return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.fragment_new_place_wizard_first_step, container, false);
        setupUI();
        return view;
    }

    public void setupUI() {
        btnNext = (Button) view.findViewById(R.id.btnNext);
        btnNext.setOnClickListener(this);
        btnSingleRoom = (Button) view.findViewById(R.id.btnSingleRoom);
        btnSingleRoom.setOnClickListener(this);
        btnDoubleRoom = (Button) view.findViewById(R.id.btnDoubleRoom);
        btnDoubleRoom.setOnClickListener(this);
        btnStudioFlat = (Button) view.findViewById(R.id.btnStudioFlat);
        btnStudioFlat.setOnClickListener(this);
        btnApartment = (Button) view.findViewById(R.id.btnApartment);
        btnApartment.setOnClickListener(this);
        btnChangeDate = (Button) view.findViewById(R.id.changeDate);
        btnChangeDate.setOnClickListener(this);
        lblAvailableFrom = (TextView) view.findViewById(R.id.lblAvailableFrom);
        tfStreet = (EditText) view.findViewById(R.id.tfStreet);
        tfCivic = (EditText) view.findViewById(R.id.tfCivic);
        tfStair = (EditText) view.findViewById(R.id.tfStair);
        tfFloor = (EditText) view.findViewById(R.id.tfFloor);
        tfCity = (EditText) view.findViewById(R.id.tfCity);
        tfPostalCode = (EditText) view.findViewById(R.id.tfPostalAddress);
    }

    AlertDialog availableFromDialog;

    private boolean enoughDataToContinue() {
        boolean ret = true;
        ret &= tfStreet.getText().length() != 0;
        ret &= tfCivic.getText().length() != 0;
        ret &= tfCity.getText().length() != 0;
        return ret;
    }

    private void collectUserData() {
        Address a = new Address();
        a.setStreet(String.valueOf(tfStreet.getText()));
        a.setNumber(String.valueOf(tfCivic.getText()));
        a.setFloor(String.valueOf(tfFloor.getText()));
        a.setStair(String.valueOf(tfStair.getText()));
        a.setCity(String.valueOf(tfCity.getText()));
        a.setPostalCode(String.valueOf(tfPostalCode.getText()));
        place.setApartment(new Apartment());
        place.getApartment().setAddress(a);
        MiscServices.setCoordinates(place.getApartment());
        Log.d(TAG, "first step done:" + new ObjectMapper().convertValue(place, Map.class).toString());
    }

    //TODO aggionare il toast
    private void notifyUserOfInputIssues() {
        Toast.makeText(getActivity().getApplicationContext(), "Complete all the fields to continue",
                Toast.LENGTH_LONG).show();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btnNext:
                if (enoughDataToContinue()) {
                    collectUserData();
                    pager.setCurrentItem(pager.getCurrentItem() + 1, true);
                }
                else
                    notifyUserOfInputIssues();
                break;
            case R.id.changeDate:
                AvailableFromDialogBuilder availableFromDialogBuilder = new AvailableFromDialogBuilder(getActivity());
                if (place.getAvailableFrom() != null)
                    availableFromDialogBuilder.setValue(place.getAvailableFrom());
                availableFromDialogBuilder.setPositiveButton(R.string.my_continue, this);
                availableFromDialog = availableFromDialogBuilder.show();
                break;
            case R.id.btnSingleRoom:
                Log.v(TAG, "SingleRoom pressed");
                clearSelection();
                btnSingleRoom.setSelected(true);
                place.setAccomodationType(Place.SINGLE_ROOM);
                break;
            case R.id.btnDoubleRoom:
                Log.v(TAG, "DoubleRoom pressed");
                clearSelection();
                btnDoubleRoom.setSelected(true);
                place.setAccomodationType(Place.DOUBLE_ROOM);
                break;
            case R.id.btnApartment:
                Log.v(TAG, "Apartment pressed");
                clearSelection();
                btnApartment.setSelected(true);
                place.setAccomodationType(Place.STANDARD_RENT);
                break;
            case R.id.btnStudioFlat:
                Log.v(TAG, "StudioFlat pressed");
                clearSelection();
                btnStudioFlat.setSelected(true);
                place.setAccomodationType(Place.STUDIO_FLAT);
                break;
            default:
                Log.e(TAG, getResources().getString(R.string.error_ID) + v.getId());
        }
    }

    public void clearSelection() {
        btnApartment.setSelected(false);
        btnSingleRoom.setSelected(false);
        btnDoubleRoom.setSelected(false);
        btnStudioFlat.setSelected(false);
    }

    ;

    @Override
    public void onClick(DialogInterface dialog, int which) {
        if (dialog == availableFromDialog) {
            DatePicker datePicker = (DatePicker) availableFromDialog.findViewById(R.id.dpAvailableFrom);
            Calendar cal = Calendar.getInstance();
            cal.set(Calendar.DAY_OF_MONTH, datePicker.getDayOfMonth());
            cal.set(Calendar.MONTH, datePicker.getMonth());
            cal.set(Calendar.YEAR, datePicker.getYear());
            place.setAvailableFrom(cal.getTime());
            lblAvailableFrom.setText(datePicker.getDayOfMonth() + " - " + cal.getDisplayName(Calendar.MONTH, Calendar.SHORT, getResources().getConfiguration().locale) + " - " + datePicker.getYear());
        } else Log.e(TAG, getResources().getString(R.string.error_dialog));
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mListener = (OnFragmentInteractionListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public void setPager(ViewPager pager) {
        this.pager = pager;
    }

    public ViewPager getPager() {
        return pager;
    }

    public interface OnFragmentInteractionListener {
        // TODO: valutare se serve
        public void onFragmentInteraction(Uri uri);
    }
}

即使必须始终启用向后滑动（从左到右），如何禁用滑动到下一个片段（从右到左）？

Answer 1

首先，提一点建议；对于以下每一行，都不需要 new 因为该方法是静态的：

NewPlaceWizardFirstStepFragment f1 = NewPlaceWizardFirstStepFragment.newInstance(place);

就是说，我可能只是向您的寻呼机适配器添加一些逻辑，以根据已完成页面的数量来限制计数。即，如果您在第 4 步，则计数为 4。完成第 4 步后，增加计数以允许用户滑动到下一个片段。

查看此堆栈溢出 post 示例：

ViewPager disable swiping to a certain direction

Answer 2

阻止页面滑动的最佳方法是控制是否在 PageViewActivity.java（我的 MainActivity）

中的 onPageScrolled 内填充编辑文本

public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

 Log.i("test", "onPageScrolled - position = " + position);

 currentPage = position;
 txt1 = (EditText) findViewById(R.id.name_input);

 if(position == 0) {

     if(txt1.getText().toString().trim().length() == 0) {                   
            pager.setCurrentItem(0);

     } else if(txt1.getText().toString().trim().length() > 0) {               
            // DO NOTHING               
     }            
}
}

Android - 对未正确填写的数据禁用向前滑动

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