Question

我是android的新手。我的任务是创建一个Android应用程序，其中一个选项卡可以刷到无限次。我的第一个屏幕必须显示当前日期，并且在向前滑动时它应该增加到明天的日期我不知道如何实施它。请建议并指导我的朋友。

谢谢。

我的主要活动在这里

public class MainActivity extends AppCompatActivity {

    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link FragmentPagerAdapter} derivative, which will keep every
     * loaded fragment in memory. If this becomes too memory intensive, it
     * may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */
    private SectionsPagerAdapter mSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will host the section contents.
     */
    private ViewPager mViewPager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);



    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";

        public PlaceholderFragment() {
        }

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            TextView textView = (TextView) rootView.findViewById(R.id.section_label);
            textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
            return rootView;
        }
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

        public SectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }



        @Override
        public int getCount() {

            return 100;
        }


        @Override
        public Fragment getItem(int position) {
                Tab2 tab2=new Tab2();
                return tab2;
        }

        @Override
        public CharSequence getPageTitle(int position) {

                    return "SECTION 3";

        }

    }
}

我的片段活动在这里

public class Tab2 extends Fragment {
    String strDate;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");

        for (int i = 0;i<=100;i++) {
                if (i < 1) {
                    try {
                        Date myDate = sdf.parse("15/07/2017");
                        Calendar c = Calendar.getInstance();
                        c.setTime(myDate);
                        c.set(Calendar.DATE, c.get(Calendar.DATE) + 1);
                        Date newDate = c.getTime();
                        strDate = sdf.format(newDate);
                    } catch (ParseException e) {
                        e.printStackTrace();

                    }
                }
           else {
                    Date day = new Date();
                    strDate = sdf.format(new Date(day.getTime()));
                }
        }
        return inflater.inflate(R.layout.tab2,container,false );
    }
    @Override
    public void onStart() {
        super.onStart();

        TextView textView2 =  getView().findViewById(R.id.textView2);
        textView2.setText(strDate);
    }
}

Answer 1

您可以使用片段的位置将日期添加到当前日期。第一个片段的位置为0，因此添加0天。第二个片段的位置是1，所以添加1天到目前为止等等。

这是Tab2片段代码：

public class Tab2 extends Fragment {
    private int position;


    public Tab2() {
    }

    public static Tab2 newInstance(int position) {
        Tab2 fragment = new Tab2();
        Bundle args = new Bundle();
        args.putInt("position", position);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            position = getArguments().getInt("position");
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_t2, container, false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
        Calendar c = Calendar.getInstance();
        c.add(Calendar.DAY_OF_MONTH, position);
        String dt = sdf.format(c.getTime()).toString();


        TextView textView2 =  getView().findViewById(R.id.textView2);
        textView2.setText(dt);
    }

现在，使用SectionPagerAdapter的{{1}}方法，将getItem发送到框架：

position

如何在单个选项卡中增加日期？

1 个答案: