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我使用 Eclipse 模板来生成滑动布局。我已经使用 switch/case 将页面从 3 扩展到 5。我还在虚拟片段中放入了一个图像视图。现在我有 5 个具有相同图像的片段。如何管理单个实例，以便将不同的内容放入其中？

public class MainActivity extends FragmentActivity implements
    ActionBar.TabListener {

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 = getActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    // Create the adapter that will return a fragment for each of the five
    // 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 boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@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) {
}

/**
 * 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 Fragment getItem(int position) {
        // getItem is called to instantiate the fragment for the given page.
        // Return a DummySectionFragment (defined as a static inner class
        // below) with the page number as its lone argument.
        Fragment fragment = new DummySectionFragment();
        Bundle args = new Bundle();
        args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 5;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        Locale l = Locale.getDefault();
        switch (position) {
        case 0:
            return getString(R.string.title_section1).toUpperCase(l);
        case 1:
            return getString(R.string.title_section2).toUpperCase(l);
        case 2:
            return getString(R.string.title_section3).toUpperCase(l);
        case 3:
            return getString(R.string.title_section4).toUpperCase(l);
        case 4:
            return getString(R.string.title_section5).toUpperCase(l);
        }
        return null;
    }
}

/**
 * A dummy fragment representing a section of the app, but that simply
 * displays dummy text.
 */
public static class DummySectionFragment extends Fragment {
    /**
     * The fragment argument representing the section number for this
     * fragment.
     */
    public static final String ARG_SECTION_NUMBER = "section_number";

    public DummySectionFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main_dummy,
                container, false);
        TextView dummyTextView = (TextView) rootView
                .findViewById(R.id.section_label);
        dummyTextView.setText(Integer.toString(getArguments().getInt(
                ARG_SECTION_NUMBER)));
        return rootView;
    }
}

}

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1 回答 1

1

这取决于数据的不同程度。如果每个片段都只有一个 ImageView，您可以像您正在做的那样重用相同的片段。您只需要检查您的 getItem 方法中的位置并通过捆绑将不同的数据发送到该片段的实例。然后在 DummySectionFragment 中，您可以检查传递给它的数据，即使它只是位置，并根据数据/位置添加不同的图像。

如果每个片段上的内容会有所不同，那么您应该为每个部分创建不同的片段。因此，不是只有一个 DummySectionFragment ，而是每个部分都有一个不同的片段，并根据您的需要为每个片段提供新的布局。

除非您只使用位置来修改每个片段中的数据，否则您的 getItem 应该如下所示：

@Override
public Fragment getItem(int position) {
    Fragment fragment = null;
    Bundle args = new Bundle();

    switch(position){
         case 0:
          fragment = new DummySectionFragment();
          args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
          fragment.setArguments(args);
         break;
         case 1:
          fragment = new DummySectionFragment();
          args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
          fragment.setArguments(args);
         break;
         case 2:
          fragment = new DummySectionFragment();
          args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
          fragment.setArguments(args);
         break;
    }
    return fragment;
}

唯一的区别是，如果您在每种情况下都使用第二种方法，您将实例化一个不同的片段而不是同一个片段。

如果您只想根据片段的位置更改图像，您可以保持代码相同，只需检查 DummySectionFragment 中的位置，如下所示：

 @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_main_dummy,
            container, false);
    int position = Integer.toString(getArguments().getInt(
            ARG_SECTION_NUMBER))

    if(position == 1){
      //Your on the first tab..
    }
    return rootView;
}

祝你好运！

于 2013-11-11T15:16:14.670 回答