How to set active item in the Action Bar drop-down

问题:

I'm trying to fix the issue with restarting activity on orientation changes.

I have an ActionBar with drop-down list navigation and after every rotation first element of this list is being activated. Keeping fragment content wasn't difficult, but I don't know how to set active list item.

Here is the definition of ActionBar:

getActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
ArrayAdapter<CharSequence> list = ArrayAdapter
    .createFromResource(this, R.array.action_list, android.R.layout.simple_dropdown_item_1line);
list.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
getActionBar().setListNavigationCallbacks(list, this);

And here is my workaround:

@Override
public boolean onNavigationItemSelected(int itemPosition, long itemId) {
    if (!application.isRotated) {
        application.activePosition = itemPosition;
        application.activeId = itemId;
        getFragmentManager().beginTransaction()
            .replace(android.R.id.content, MyFragment.newInstance(itemPosition))
            .commit();
    } else {
        application.isRotated = false;
        this.onNavigationItemSelected(application.activePosition, application.activeId);            
    }
    return true;
}

@Override
protected void onStop() {
    super.onStop();
    application.isRotated = true;
}

I'm not sure it's the best solution though.

回答1:

I just found that function. It is setSelectedNavigationItem(int position).

Set the selected navigation item in list or tabbed navigation modes.

Example:

actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
actionBar.setListNavigationCallbacks(adapter, this);
actionBar.setSelectedNavigationItem(position);

回答2:

As of support library v7, you just need to save / restore the state of the ActionBar:

private static final String STATE_SELECTED_NAVIGATION_ITEM = "selectedNavItem";

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    // Restore the previously serialized current dropdown position.
    if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM)) {
        getSupportActionBar().setSelectedNavigationItem(
                savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM));
    }
}

@Override
public void onSaveInstanceState(Bundle outState) {
    // Serialize the current dropdown position.
    outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getSupportActionBar()
            .getSelectedNavigationIndex());
}

回答3:

I was also experiencing the same issue. Making a lot of research I found the solution here:

http://mohitum.wordpress.com/tutorials/android/ -->under Tip 5.

Implement OnPageChangeListener and in the onPageSelected(int position) call this method like this:

@Override
public void onPageSelected(int position) {
  mActionBar.setSelectedNavigationItem(position);
  selectInSpinnerIfPresent(position, true);
}
private void selectInSpinnerIfPresent(int position, boolean animate) {
  try {
    ActionBar actionBarView = mActionBar;
    Class<?> actionBarViewClass = actionBarView.getClass();
    Field mTabScrollViewField = actionBarViewClass.getDeclaredField(“mTabScrollView”);
    mTabScrollViewField.setAccessible(true);
    Object mTabScrollView = mTabScrollViewField.get(actionBarView);
    if (mTabScrollView == null) {
      return;
    }
    Field mTabSpinnerField = mTabScrollView.getClass().getDeclaredField(“mTabSpinner”);
    mTabSpinnerField.setAccessible(true);
    Object mTabSpinner = mTabSpinnerField.get(mTabScrollView);
    if (mTabSpinner == null) {
      return;
    }
    Method setSelectionMethod = mTabSpinner.getClass().getSuperclass().getDeclaredMethod(“setSelection”, Integer.TYPE, Boolean.TYPE);
    setSelectionMethod.invoke(mTabSpinner, position, animate);
    Method requestLayoutMethod = mTabSpinner.getClass().getSuperclass().getDeclaredMethod(“requestLayout”);
    requestLayoutMethod.invoke(mTabSpinner);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

I hope this may help someone else too.

回答4:

Codesnippet on Gist

---

@Override
public void onPageScrollStateChanged(int state) {
}


@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}


@Override
public void onPageSelected(int position) {
    actionBar.setSelectedNavigationItem(position);

    selectInSpinnerIfPresent(position, true);
}


/**
 * Hack that takes advantage of interface parity between ActionBarSherlock and the native interface to reach inside
 * the classes to manually select the appropriate tab spinner position if the overflow tab spinner is showing.
 * 
 * Related issues: https://github.com/JakeWharton/ActionBarSherlock/issues/240 and
 * https://android-review.googlesource.com/#/c/32492/
 * 
 * @author [e-mail]
 */
private void selectInSpinnerIfPresent(int position, boolean animate) {
    try {
        View actionBarView = findViewById(R.id.abs__action_bar);
        if (actionBarView == null) {
            int id = getResources().getIdentifier("action_bar", "id", "android");
            actionBarView = findViewById(id);
        }

        Class<?> actionBarViewClass = actionBarView.getClass();
        Field mTabScrollViewField = actionBarViewClass.getDeclaredField("mTabScrollView");
        mTabScrollViewField.setAccessible(true);

        Object mTabScrollView = mTabScrollViewField.get(actionBarView);
        if (mTabScrollView == null) {
            return;
        }

        Field mTabSpinnerField = mTabScrollView.getClass().getDeclaredField("mTabSpinner");
        mTabSpinnerField.setAccessible(true);

        Object mTabSpinner = mTabSpinnerField.get(mTabScrollView);
        if (mTabSpinner == null) {
            return;
        }

        Method setSelectionMethod = mTabSpinner.getClass().getSuperclass().getDeclaredMethod("setSelection", Integer.TYPE, Boolean.TYPE);
        setSelectionMethod.invoke(mTabSpinner, position, animate);

        Method requestLayoutMethod = mTabSpinner.getClass().getSuperclass().getDeclaredMethod("requestLayout");
        requestLayoutMethod.invoke(mTabSpinner);
    } catch (IllegalArgumentException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    } catch (NoSuchMethodException e) {
        e.printStackTrace();
    } catch (InvocationTargetException e) {
        e.printStackTrace();
    }
}

---

this hack around the official Android Bug did it for me, the codesnippet above did not :/

回答5:

This implementation works for me (a modified version of @mohitum007's response):

public static void selectInSpinnerIfPresent(Object inActionBar,
        int position, boolean animate) {
    // get the ActionBar class
    Class<?> actionBarClass = inActionBar.getClass();

    // if it is a Jelly Bean implementation (ActionBarImplJB), get the super
    // class (ActionBarImplICS)
    if ("android.support.v7.app.ActionBarImplJB".equals(actionBarClass
            .getName())) {
        actionBarClass = actionBarClass.getSuperclass();
    }
    try {
        // try to get the mActionBar field, because the current ActionBar is
        // probably just a wrapper Class
        // if this fails, no worries, this will be an instance of the native
        // ActionBar class or from the ActionBarImplBase class
        final Field actionBarField = actionBarClass
                .getDeclaredField("mActionBar");
        actionBarField.setAccessible(true);
        inActionBar = actionBarField.get(inActionBar);
        actionBarClass = inActionBar.getClass();
    } catch (IllegalAccessException e) {
    } catch (IllegalArgumentException e) {
    } catch (NoSuchFieldException e) {
    }
    try {
        Field mTabScrollViewField = actionBarClass
                .getDeclaredField("mTabScrollView");
        mTabScrollViewField.setAccessible(true);
        Object mTabScrollView = mTabScrollViewField.get(inActionBar);
        if (mTabScrollView == null) {
            return;
        }
        Field mTabSpinnerField = mTabScrollView.getClass()
                .getDeclaredField("mTabSpinner");
        mTabSpinnerField.setAccessible(true);
        Object mTabSpinner = mTabSpinnerField.get(mTabScrollView);
        if (mTabSpinner == null) {
            return;
        }
        Method setSelectionMethod = mTabSpinner
                .getClass()
                .getSuperclass()
                .getDeclaredMethod("setSelection", Integer.TYPE,
                        Boolean.TYPE);
        setSelectionMethod.invoke(mTabSpinner, position, animate);
        Method requestLayoutMethod = mTabSpinner.getClass().getSuperclass()
                .getDeclaredMethod("requestLayout");
        requestLayoutMethod.invoke(mTabSpinner);
    } catch (NoSuchMethodException | InvocationTargetException
            | IllegalAccessException | IllegalArgumentException | NoSuchFieldException e) {
    }
}