如果今天是特定的一天，如何打开另一个选项卡（片段）？

Question

我正在开发一个带有片段选项卡的应用程序，我想在 activity 启动时打开另一个选项卡。如果今天是星期一 - 打开第一个选项卡，如果今天是星期二打开第二个选项卡等等。我该怎么做？

我的fragmentactivity.java:

public class FragmentActivity extends AppCompatActivity {

    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;
    SharedPreferences sp;

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

        sp = PreferenceManager.getDefaultSharedPreferences(this);
        String select_class = sp.getString("select_class", "");

        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        //getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new MondayFragment(), "ПН");
        adapter.addFragment(new TuesdayFragment(), "ВТ");
        adapter.addFragment(new WednesdayFragment(), "СР");
        adapter.addFragment(new ThursdayFragment(), "ЧТ");
        adapter.addFragment(new FridayFragment(), "ПТ");
        viewPager.setAdapter(adapter);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFragment(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }
}

Answer 1

尝试viewpager.setCurrentItem(index)

Answer 2

要查找当前星期几和 select 相应的特定选项卡：

Calendar calendar = Calendar.getInstance();
int day = calendar.get(Calendar.DAY_OF_WEEK); 

switch (day) {
    case Calendar.SUNDAY:
        viewPager.setCurrentItem(0);

    case Calendar.MONDAY:
        viewPager.setCurrentItem(1);

    case Calendar.TUESDAY:
        viewPager.setCurrentItem(2);
        ...
        ... //etc
}

Answer 3

首先，使用日历获取星期几：

Calendar c = Calendar.getInstance();
int date = c.get(Calendar.DAY_OF_WEEK);

现在，要确定打开哪个选项卡，最简单的方法是使用开关。您可以说 case Calendar.SUNDAY:，或 case 1:。它们是相同的，但是 Calendar.SUNDAY 更容易，因为您不需要知道天数

switch(date){

case Calendar.SUNDAY:
    //create tab
    break;

case Calendar.MONDAY:
    //create tab
    break;
and so on...

}

这是获取日期并根据输入创建选项卡的简单方法。这段代码的调用最好是在应用打开的时候调用，如果只调用一次就检查之前是否调用过。为此，请保存检查您之前是否打开过 "tab of the day" 的值。

正在检查您之前是否打开过标签页

在撰写此答案时，有 4 种不同的保存值的选项：

Internal/external

SQLite

Shared preferences

天数：

从日历中复制class。无需将这些行添加到您的项目中：

/**
* Value of the {@code DAY_OF_WEEK} field indicating Sunday.
*/
public static final int SUNDAY = 1;



/**
 * Value of the {@code DAY_OF_WEEK} field indicating Monday.
 */
public static final int MONDAY = 2;

/**
 * Value of the {@code DAY_OF_WEEK} field indicating Tuesday.
 */
public static final int TUESDAY = 3;

/**
 * Value of the {@code DAY_OF_WEEK} field indicating Wednesday.
 */
public static final int WEDNESDAY = 4;

/**
 * Value of the {@code DAY_OF_WEEK} field indicating Thursday.
 */
public static final int THURSDAY = 5;

/**
 * Value of the {@code DAY_OF_WEEK} field indicating Friday.
 */
public static final int FRIDAY = 6;

/**
 * Value of the {@code DAY_OF_WEEK} field indicating Saturday.
 */
public static final int SATURDAY = 7;

如果今天是特定的一天，如何打开另一个选项卡（片段）？

How to open another tab (fragment) if today a specific day?

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dayofweek