Question

这将是关于标签的最后一个问题，我保证:)（也许）因此，从以前的问题和尝试和错误我有FragmentPagerAdapter调用PagerAdapter创建一些选项卡，并使我能够动态创建新选项卡。问题是新选项卡将始终插入到现有选项卡的右侧：

（图片：

我尝试了以下内容：

添加＆＃34; null＆＃34;的静态条目在创建初始选项卡集时会跳过。然后在创建＆＃34; Temp Tab＆＃34;我可以将该条目覆盖到我想要的任何片段。给了我一些奇怪的IllegalSTateException ......

我认为这项工作效果最好，实际上真的很想工作：而不是添加片段：

private final List<Fragment> mFragments = new ArrayList<Fragment>();

public void addFragment(Fragment fragment) {
    mFragments.add(fragment);
    notifyDataSetChanged();
}

使用

mFragments.add(0, fragment);

但是它给出了IllegalStateException，并带有消息：

Can't change tag of fragment ChatFragment

当我尝试添加临时片段时。现在，有两个问题：

是否有解决该片段标签的方法，我可以暂时取走所有片段标签并重建它们全部或其他东西吗？或
有更好更优雅的方法吗？或者我应该重新设计我的UI，以便可以使用右侧的选项卡？：P

FragmentPagerAdapter：

public class PagerAdapter extends FragmentPagerAdapter {

  private Context mContext;

  public PagerAdapter(FragmentManager fm, Context context) {
    super(fm);
    mContext = context;
  }

  private final List<Fragment> mFragments = new ArrayList<Fragment>();
  public void addFragment(Fragment fragment) {
    mFragments.add(fragment);
    notifyDataSetChanged();
  }

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

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

  @Override
  public String getPageTitle(int position) {

    switch (position) {
    case 0:
      return mContext.getString(R.string.tab_title_chats);
    case 1:
      return mContext.getString(R.string.tab_title_contacts);
    case 2:
      return mContext.getString(R.string.tab_title_create);
    }
    return "WOOPS";

  }

}

MainActivty：

public class LaunchActivity extends FragmentActivity implements ActionBar.TabListener {

  private PagerAdapter mAdapter;
  private FragmentManager man;
  private ViewPager mViewPager;
  private ActionBar actionBar;

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

    // Set up the action bar.
    actionBar = getActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    // Layout stuff
    mViewPager = (ViewPager) findViewById(R.id.masterViewPager);

    // Creating the mAdapter and initializing the mViewPager
    man = getSupportFragmentManager();
    mAdapter = new PagerAdapter(man, getApplicationContext());
    mViewPager.setAdapter(mAdapter);

    for (int i = 0; i < 2; i++) {
      makeFragments(i);
      System.out.println("Baking tasty fragment instances...nom nom nom");
    }

    // Called when tab changes
    mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
      @Override
      public void onPageSelected(int position) {
        actionBar.setSelectedNavigationItem(position);
      }
    });

    for (int i = 0; i < mAdapter.getCount(); i++) {
      System.out.println("Working...");

      actionBar.addTab(actionBar.newTab().setText(mAdapter.getPageTitle(i)).setTabListener(this));
    }

  }

  // Add fragment instances to ArrayList depending on their future position on the ActionBar
  private void makeFragments(int i) {

    if (i == 0) {
      mAdapter.addFragment(ChatFragment.getInstance());

    }
    else if (i == 1) {
      mAdapter.addFragment(ContactFragment.getInstance());
    }
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.layout_container, menu);
    return true;

  }

  @Override
  public void onTabSelected(Tab tab, FragmentTransaction ft) {
    mViewPager.setCurrentItem(tab.getPosition());

  }

  public void addTab(int i) {
    mAdapter.addFragment(ComposeFragment.getInstance());
    System.out.println("Created new Fragment, now adding it as a tab");
    actionBar.addTab(actionBar.newTab().setText(mAdapter.getPageTitle(i)).setTabListener(this));
    System.out.println("Added it as a tab. Hurray");

  }

  /** IGNORE BELOW **/

  @Override
  public void onTabUnselected(Tab tab, FragmentTransaction ft) {
  }

  @Override
  public void onTabReselected(Tab tab, FragmentTransaction ft) {
  }



}

堆栈跟踪：

    03-18 18:32:29.274: E/AndroidRuntime(26435): FATAL EXCEPTION: main
    03-18 18:32:29.274: E/AndroidRuntime(26435): java.lang.IllegalStateException: Can't change tag of fragment ChatFragment{41492428 #1 id=0x7f070004 android:switcher:2131165188:1}: was android:switcher:2131165188:1 now android:switcher:2131165188:2
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:398)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:389)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:99)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:801)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.view.ViewPager.populate(ViewPager.java:992)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:523)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:495)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.view.ViewPager.dataSetChanged(ViewPager.java:875)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.view.ViewPager$PagerObserver.onChanged(ViewPager.java:2690)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.support.v4.view.PagerAdapter.notifyDataSetChanged(PagerAdapter.java:276)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at com.package.subpackage.components.PagerAdapter.addFragment(PagerAdapter.java:25)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at com.package.subpackage.someapp.core.LaunchActivity.addTab(LaunchActivity.java:116)
    03-18 18:32:29.274: E/AndroidRuntime(26435):    at com.

com.package.subpackage.fragments.full.ChatFragment$1.onClick(ChatFragment.java:51)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.view.View.performClick(View.java:4204)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.view.View$PerformClick.run(View.java:17355)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.os.Handler.handleCallback(Handler.java:725)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.os.Handler.dispatchMessage(Handler.java:92)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.os.Looper.loop(Looper.java:137)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at android.app.ActivityThread.main(ActivityThread.java:5041)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at java.lang.reflect.Method.invokeNative(Native Method)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at java.lang.reflect.Method.invoke(Method.java:511)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-18 18:32:29.274: E/AndroidRuntime(26435):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

我可以通过覆盖OnPageChangeListener的onPageSelected方法来实现这一点。考虑您按此顺序有三个页面A＆lt; - ＆gt; B＆lt; - ＆gt; C.如果我们从A向右滚动，目标是达到C，如果我们从C向左滚动，则达到A。

要执行此操作，请将您的页面定义为5页（3 + 2），然后按如下方式组织页面：

℃下; - ＆gt;一种与LT; - ＆GT; B＆LT; - ＆GT;℃下; - ＆gt;一种

现在在onPageSelected方法中，检查并且如果位置为0，则将其更改为3（getCount（） - 2）并且如果position为4（getCount（） - 1），则将其更改为1.确保此类似可以帮助你。

由于

使用FragmentPagerAdapter向左侧添加选项卡

1 个答案: