Show and hide Item in ActionBar depending on the selected Tab

Question

I need to get the numerical position of the selected Tab for show/hide the ActionBar items in the MainActivity. For example, I'm in Tab1, show the item for write a new message, go in Tab2, hide the new message item and show the one for add an user to the address book... The structure of the app is: MainActivity with Tab Layout (4 Tabs) with a FragmentStatePagerAdapter that manage all the Fragments.

MainActivity

public class MainActivity extends AppCompatActivity {

// Declaring Your View and Variables

Toolbar toolbar;
ViewPager pager;
ViewPagerAdapter adapter;
SlidingTabLayout tabs;
CharSequence Titles[]={"1","2","3","4"};
int Numboftabs =4;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //getSupportActionBar().setElevation(0);
    setContentView(R.layout.activity_main);

    // Creating The Toolbar and setting it as the Toolbar for the activity

    toolbar = (Toolbar) findViewById(R.id.tool_bar);
    //setSupportActionBar(toolbar);

    // Creating The ViewPagerAdapter and Passing Fragment Manager, Titles fot the Tabs and Number Of Tabs.
    adapter =  new ViewPagerAdapter(getSupportFragmentManager(),Titles,Numboftabs);

    // Assigning ViewPager View and setting the adapter
    pager = (ViewPager) findViewById(R.id.pager);
    pager.setAdapter(adapter);

    // Assiging the Sliding Tab Layout View
    tabs = (SlidingTabLayout) findViewById(R.id.tabs);
    tabs.setDistributeEvenly(true); // To make the Tabs Fixed set this true, This makes the tabs Space Evenly in Available width

    // Setting Custom Color for the Scroll bar indicator of the Tab View
    tabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {
        @Override
        public int getIndicatorColor(int position) {
            return ContextCompat.getColor(getApplicationContext(), R.color.darkgreen);
        }
    });

    // Setting the ViewPager For the SlidingTabsLayout
    tabs.setViewPager(pager);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}


@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    switch (id) {
        case R.id.action_settings:
            Intent intentMSett = new Intent(this, MainSettings.class);
            startActivity(intentMSett);
            break;
        case R.id.action_add_user:
            Intent intent = new Intent(this, CreateUser.class);
            startActivityForResult(intent, 101);
            break;
        case R.id.action_search:
            Toast.makeText(getApplicationContext(),
                    "search", Toast.LENGTH_SHORT).show();
            break;
    }

    return super.onOptionsItemSelected(item);
}

}

ViewPagerAdapter

public class ViewPagerAdapter extends FragmentStatePagerAdapter {

CharSequence Titles[]; // This will Store the Titles of the Tabs which are Going to be passed when ViewPagerAdapter is created
int NumbOfTabs; // Store the number of tabs, this will also be passed when the ViewPagerAdapter is created
private Context context;

// Build a Constructor and assign the passed Values to appropriate values in the class
public ViewPagerAdapter(FragmentManager fm,CharSequence mTitles[], int mNumbOfTabsumb) {
    super(fm);

    this.Titles = mTitles;
    this.NumbOfTabs = mNumbOfTabsumb;

}

//This method return the fragment for the every position in the View Pager
@Override
public Fragment getItem(int position) {

    if(position == 0) // if the position is 0 we are returning the First tab
    {
        Tab1 tab1 = new Tab1();
        return tab1;
    } else if(position == 1){
        Tab2 tab2 = new Tab2();
        return tab2;
    } else if(position == 2) {
        Tab3 tab3 = new Tab3();
        return tab3;
    } else if(position == 3) {
        Tab4 tab4 = new Tab4();
        return tab4;
    } else {
        Tab1 tab1 = new Tab1();
        return tab1;
    }
}

// This method return the titles for the Tabs in the Tab Strip

@Override
public CharSequence getPageTitle(int position) {

    return Titles[position];
}

// This method return the Number of tabs for the tabs Strip

@Override
public int getCount() {
    return NumbOfTabs;
}
}

Searching for solutions I've found this method for the MainActivity:

 @Override
 public boolean onPrepareOptionsMenu(Menu menu) {
    // TODO Auto-generated method stub
    MenuInflater inflater = getMenuInflater();
    int currentTab = tabHost.getCurrentTab();
    Toast.makeText(getApplicationContext(), currentTab+"", Toast.LENGTH_SHORT);
    menu.clear();
    if (currentTab == 0) {
        inflater.inflate(R.menu.first, menu);  //  menu for photospec.
    } else {
        inflater.inflate(R.menu.second, menu);  // menu for songspec
    }
    return super.onPrepareOptionsMenu(menu);
}

SlidingTabLayout

public class SlidingTabLayout extends HorizontalScrollView {
/**
 * Allows complete control over the colors drawn in the tab layout. Set with
 * {@link #setCustomTabColorizer(TabColorizer)}.
 */
public interface TabColorizer {

    /**
     * @return return the color of the indicator used when {@code position} is selected.
     */
    int getIndicatorColor(int position);

}

private static final int TITLE_OFFSET_DIPS = 24;
private static final int TAB_VIEW_PADDING_DIPS = 16;
private static final int TAB_VIEW_TEXT_SIZE_SP = 12;

private int mTitleOffset;

private int mTabViewLayoutId;
private int mTabViewTextViewId;
private boolean mDistributeEvenly;

private ViewPager mViewPager;
private SparseArray<String> mContentDescriptions = new SparseArray<String>();
private ViewPager.OnPageChangeListener mViewPagerPageChangeListener;

private final SlidingTabStrip mTabStrip;

public SlidingTabLayout(Context context) {
    this(context, null);
}

public SlidingTabLayout(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
}

public SlidingTabLayout(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);

    // Disable the Scroll Bar
    setHorizontalScrollBarEnabled(false);
    // Make sure that the Tab Strips fills this View
    setFillViewport(true);

    mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density);

    mTabStrip = new SlidingTabStrip(context);
    addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
}

/**
 * Set the custom {@link TabColorizer} to be used.
 *
 * If you only require simple custmisation then you can use
 * {@link #setSelectedIndicatorColors(int...)} to achieve
 * similar effects.
 */
public void setCustomTabColorizer(TabColorizer tabColorizer) {
    mTabStrip.setCustomTabColorizer(tabColorizer);
}

public void setDistributeEvenly(boolean distributeEvenly) {
    mDistributeEvenly = distributeEvenly;
}

/**
 * Sets the colors to be used for indicating the selected tab. These colors are treated as a
 * circular array. Providing one color will mean that all tabs are indicated with the same color.
 */
public void setSelectedIndicatorColors(int... colors) {
    mTabStrip.setSelectedIndicatorColors(colors);
}

/**
 * Set the {@link ViewPager.OnPageChangeListener}. When using {@link SlidingTabLayout} you are
 * required to set any {@link ViewPager.OnPageChangeListener} through this method. This is so
 * that the layout can update it's scroll position correctly.
 *
 * @see ViewPager#setOnPageChangeListener(ViewPager.OnPageChangeListener)
 */
public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
    mViewPagerPageChangeListener = listener;
}

/**
 * Set the custom layout to be inflated for the tab views.
 *
 * @param layoutResId Layout id to be inflated
 * @param textViewId id of the {@link TextView} in the inflated view
 */
public void setCustomTabView(int layoutResId, int textViewId) {
    mTabViewLayoutId = layoutResId;
    mTabViewTextViewId = textViewId;
}

/**
 * Sets the associated view pager. Note that the assumption here is that the pager content
 * (number of tabs and tab titles) does not change after this call has been made.
 */
public void setViewPager(ViewPager viewPager) {
    mTabStrip.removeAllViews();

    mViewPager = viewPager;
    if (viewPager != null) {
        viewPager.setOnPageChangeListener(new InternalViewPagerListener());
        populateTabStrip();
    }
}

/**
 * Create a default view to be used for tabs. This is called if a custom tab view is not set via
 * {@link #setCustomTabView(int, int)}.
 */
protected TextView createDefaultTabView(Context context) {
    TextView textView = new TextView(context);
    textView.setGravity(Gravity.CENTER);
    textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP);
    textView.setTypeface(Typeface.DEFAULT_BOLD);
    textView.setLayoutParams(new LinearLayout.LayoutParams(
            ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));

    TypedValue outValue = new TypedValue();
    getContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground,
            outValue, true);
    textView.setBackgroundResource(outValue.resourceId);
    textView.setAllCaps(true);

    int padding = (int) (TAB_VIEW_PADDING_DIPS * getResources().getDisplayMetrics().density);
    textView.setPadding(padding, padding, padding, padding);

    return textView;
}

private void populateTabStrip() {
    final PagerAdapter adapter = mViewPager.getAdapter();
    final View.OnClickListener tabClickListener = new TabClickListener();

    for (int i = 0; i < adapter.getCount(); i++) {
        View tabView = null;
        TextView tabTitleView = null;

        if (mTabViewLayoutId != 0) {
            // If there is a custom tab view layout id set, try and inflate it
            tabView = LayoutInflater.from(getContext()).inflate(mTabViewLayoutId, mTabStrip,
                    false);
            tabTitleView = (TextView) tabView.findViewById(mTabViewTextViewId);
        }

        if (tabView == null) {
            tabView = createDefaultTabView(getContext());
        }

        if (tabTitleView == null && TextView.class.isInstance(tabView)) {
            tabTitleView = (TextView) tabView;
        }

        if (mDistributeEvenly) {
            LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams) tabView.getLayoutParams();
            lp.width = 0;
            lp.weight = 1;
        }

        tabTitleView.setText(adapter.getPageTitle(i));
        tabView.setOnClickListener(tabClickListener);
        String desc = mContentDescriptions.get(i, null);
        if (desc != null) {
            tabView.setContentDescription(desc);
        }

        mTabStrip.addView(tabView);
        if (i == mViewPager.getCurrentItem()) {
            tabView.setSelected(true);
        }
    }
}

private void addIconTab(final int position, int resId) {

    ImageButton tab = new ImageButton(getContext());
    tab.setImageResource(resId);

}

public void setContentDescription(int i, String desc) {
    mContentDescriptions.put(i, desc);
}

@Override
protected void onAttachedToWindow() {
    super.onAttachedToWindow();

    if (mViewPager != null) {
        scrollToTab(mViewPager.getCurrentItem(), 0);
    }
}

private void scrollToTab(int tabIndex, int positionOffset) {
    final int tabStripChildCount = mTabStrip.getChildCount();
    if (tabStripChildCount == 0 || tabIndex < 0 || tabIndex >= tabStripChildCount) {
        return;
    }

    View selectedChild = mTabStrip.getChildAt(tabIndex);
    if (selectedChild != null) {
        int targetScrollX = selectedChild.getLeft() + positionOffset;

        if (tabIndex > 0 || positionOffset > 0) {
            // If we're not at the first child and are mid-scroll, make sure we obey the offset
            targetScrollX -= mTitleOffset;
        }

        scrollTo(targetScrollX, 0);
    }
}

private class InternalViewPagerListener implements ViewPager.OnPageChangeListener {
    private int mScrollState;

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        int tabStripChildCount = mTabStrip.getChildCount();
        if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) {
            return;
        }

        mTabStrip.onViewPagerPageChanged(position, positionOffset);

        View selectedTitle = mTabStrip.getChildAt(position);
        int extraOffset = (selectedTitle != null)
                ? (int) (positionOffset * selectedTitle.getWidth())
                : 0;
        scrollToTab(position, extraOffset);

        if (mViewPagerPageChangeListener != null) {
            mViewPagerPageChangeListener.onPageScrolled(position, positionOffset,
                    positionOffsetPixels);
        }
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        mScrollState = state;

        if (mViewPagerPageChangeListener != null) {
            mViewPagerPageChangeListener.onPageScrollStateChanged(state);
        }
    }

    @Override
    public void onPageSelected(int position) {
        if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
            mTabStrip.onViewPagerPageChanged(position, 0f);
            scrollToTab(position, 0);
        }
        for (int i = 0; i < mTabStrip.getChildCount(); i++) {
            mTabStrip.getChildAt(i).setSelected(position == i);
        }
        if (mViewPagerPageChangeListener != null) {
            mViewPagerPageChangeListener.onPageSelected(position);
        }
    }

}

private class TabClickListener implements View.OnClickListener {
    @Override
    public void onClick(View v) {
        for (int i = 0; i < mTabStrip.getChildCount(); i++) {
            if (v == mTabStrip.getChildAt(i)) {
                mViewPager.setCurrentItem(i);
                return;
            }
        }
    }
}

}

But I don't know how to set getCurrentTab() for obtain the Tab position, instead in the ViewPagerAdapter I've the position but I don't know how to get the Menu from the MainActivity. Solutions?

Answer 1

I have solved adding a method with OnPageChangeListener in MainActivity, i post the updated code:

MainActivity

public class MainActivity extends AppCompatActivity {

// Declaring Your View and Variables

Toolbar toolbar;
ViewPager pager;
ViewPagerAdapter adapter;
SlidingTabLayout tabs;
CharSequence Titles[]={"1","2","3","4"};
int Numboftabs =4;
Integer tabSelected = 1;

public static Integer MYACTIVITY_REQUEST_CODE = 101;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //getSupportActionBar().setElevation(0);
    setContentView(R.layout.activity_main);

    //
    // Creating The Toolbar and setting it as the Toolbar for the activity

    toolbar = (Toolbar) findViewById(R.id.tool_bar);
    //setSupportActionBar(toolbar);

    // Creating The ViewPagerAdapter and Passing Fragment Manager, Titles fot the Tabs and Number Of Tabs.
    adapter =  new ViewPagerAdapter(getSupportFragmentManager(),Titles,Numboftabs);

    // Assigning ViewPager View and setting the adapter
    pager = (ViewPager) findViewById(R.id.pager);
    pager.setAdapter(adapter);

    // Assiging the Sliding Tab Layout View
    tabs = (SlidingTabLayout) findViewById(R.id.tabs);
    tabs.setDistributeEvenly(true); // To make the Tabs Fixed set this true, This makes the tabs Space Evenly in Available width

    // Setting Custom Color for the Scroll bar indicator of the Tab View
    tabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {
        @Override
        public int getIndicatorColor(int position) {
            return ContextCompat.getColor(getApplicationContext(), R.color.darkgreen);
        }
    });

    // Setting the ViewPager For the SlidingTabsLayout
    tabs.setViewPager(pager);

}


@Override
public boolean onPrepareOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    tabSelected = getCurrentTab();

    switch (tabSelected) {
        case 1:
            //other..
            break;
        case 2:
            //other..
            break;
        case 3:
            MenuItem addUser = menu.findItem(R.id.action_add_user);
            addUser.setVisible(true);
            break;
        case 4:
            MenuItem message = menu.findItem(R.id.action_message);
            message.setVisible(true);
            break;
    }
    return super.onPrepareOptionsMenu(menu);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    switch (id) {
        case R.id.action_settings:
            Intent intentMSett = new Intent(this, MainSettings.class);
            startActivity(intentMSett);
            break;
        case R.id.action_add_user:
            Intent intentCUser = new Intent(this, CreateUser.class);
            startActivityForResult(intentCUser, 101);
            break;
        case R.id.action_message:
            Intent intentMessage = new Intent(this, CreateMessage.class);
            startActivityForResult(intentMessage, 102);
            break;
    }

    return super.onOptionsItemSelected(item);
}


public Integer getCurrentTab(){
    pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {
            switch (position) {
                case 0:
                    tabSelected = 1;
                    break;
                case 1:
                    tabSelected = 2;
                    break;
                case 2:
                    tabSelected = 3;
                    break;
                case 3:
                    tabSelected = 4;
                    break;
            }
        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
    });
    return tabSelected;
}

}

Answer 2

Step #1: Create one menu resource that contains all the action bar items. If necessary, have one or more have android:visible="false" in the resource.

Step #2: In onPrepareOptionsMenu(), call findItem() on the Menu, after inflating the resource, to retrieve the MenuItem objects whose state varies. Hold onto these in fields of your activity.

Step #3: Add an OnPageChangeListener to your ViewPager, and call setVisibility() on the MenuItem objects as needed to change their state as the user chooses different tabs. Most likely, this will require changing wherever you are getting your SlidingTabLayout from, as it too probably sets an OnPageChangeListener, and there can only be one of those per ViewPager.

Answer 3

You can do it with setHasOptionMenu(Boolean);

And then in your onCreateOptionsMenu() create the icons and title, here's an example :

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
  super.onCreateOptionsMenu(menu, inflater);
  inflater.inflate(R.menu.your_fragment_menu, menu);
  //add the items here.
}

Also take a look at this example

EDIT

On each fragment you can inflate your menu as I say you've created two menu, so in one fragment on onCreateOptionsMenu() you add the first one, and the second one you add the second one, and so and so.