android - 在选项卡中使用带有类的片段 (Android)

Question

我已经完成了很多关于这方面的教程，但我仍然没有找到一个有帮助的。问题是我正在使用选项卡（带有滑动），并希望每个选项卡加载不同的类（某些选项卡将可以访问不同的数据和数据库，每个选项卡将完全不同）。我知道我需要使用片段，但教程只是让每个片段显示“Tab 1”、“Tab 2”等。有人知道解释如何做到这一点的教程吗？这让我疯狂！我花了很多时间试图弄清楚这一点。Tks

Answer 1

这是我的做法：

我的 MainActivity 与我的 ViewPager：

public class MainActivity extends SherlockFragmentActivity implements
        ActionBar.TabListener {

    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link android.support.v4.app.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}.
     */
    SectionsPagerAdapter mSectionsPagerAdapter;

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

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



        // Set up the action bar.
        final ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        // Create the adapter that will return a fragment for each of the three
        // primary sections of the app.
        mSectionsPagerAdapter = new SectionsPagerAdapter(
                getSupportFragmentManager());

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

        // When swiping between different sections, select the corresponding
        // tab. We can also use ActionBar.Tab#select() to do this if we have
        // a reference to the Tab.
        mViewPager
                .setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
                    @Override
                    public void onPageSelected(int position) {
                        actionBar.setSelectedNavigationItem(position);
                    }
                });

        // For each of the sections in the app, add a tab to the action bar.
        for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
            // Create a tab with text corresponding to the page title defined by
            // the adapter. Also specify this Activity object, which implements
            // the TabListener interface, as the callback (listener) for when
            // this tab is selected.
            actionBar.addTab(actionBar.newTab()
                    .setText(mSectionsPagerAdapter.getPageTitle(i))
                    .setTabListener(this));
        }
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab,
            FragmentTransaction fragmentTransaction) {
        // When the given tab is selected, switch to the corresponding page in
        // the ViewPager.
        mViewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab,
            FragmentTransaction fragmentTransaction) {
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab,
            FragmentTransaction fragmentTransaction) {
    }

    public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

        @Override
        public Fragment getItem(int position) {
            Fragment fragment = null;
            if (position == 0) {
                fragment = new Tab1Fragment();
            }
            if (position == 1) {
                fragment = new Tab2Fragment();
            }
            if (position == 2) {
                fragment = new Tab3Fragment();
            }
            if (position == 3) {
                fragment = new Tab4Fragment();
            }
            return fragment;
        }

        @Override
        public int getCount() {
            // Show 4 total pages.
            return 4;
        }

        @Override
        public CharSequence getPageTitle(int position) {
            switch (position) {
            case 0:
                return getString(R.string.title_section1).toUpperCase();
            case 1:
                return getString(R.string.title_section2).toUpperCase();
            case 2:
                return getString(R.string.title_section3).toUpperCase();
            case 3:
                return getString(R.string.title_section4).toUpperCase();
            }
            return null;
        }
    }


}

这将根据选择的选项卡加载不同的片段。例如，如果选择了选项卡 2，它将加载 Tab2Fragment.java