SlidingTabPagerAdapter.java

package com.netease.nim.demo.common.ui.viewpager;

import android.content.Context;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;

import com.netease.nim.uikit.common.fragment.TabFragment;

public abstract class SlidingTabPagerAdapter extends FragmentPagerAdapter implements TabFragment.State,
		PagerSlidingTabStrip.OnTabClickListener, PagerSlidingTabStrip.OnTabDoubleTapListener {

	protected final TabFragment[] fragments;

	protected final Context context;

	private final ViewPager pager;

	public abstract int getCacheCount();

	private int lastPostion = 0;

	public SlidingTabPagerAdapter(FragmentManager fm, int count, Context context, ViewPager pager) {
		super(fm);
		this.fragments = new TabFragment[count];
		this.context = context;
		this.pager = pager;
		lastPostion = 0;
	}

	@Override
	public TabFragment getItem(int pos) {
		return fragments[pos];
	}

	@Override
	public abstract int getCount();

	@Override
	public abstract CharSequence getPageTitle(int position);

	@Override
	public boolean isCurrent(TabFragment f) {
		// FROM PAGER
		int current = pager.getCurrentItem();

		// TRAVEL
		for (int index = 0; index < fragments.length; index++) {
			// CATCH
			if (f == fragments[index]) {
				// MATCH
				if (index == current) {
					return true;
				}
			}
		}

		// ANY PROBLEM
		return false;
	}

	public void onPageSelected(int position) {
		TabFragment fragment = getFragmentByPosition(position);

		// INSTANCE
		if (fragment == null) {
			return;
		}

		fragment.onCurrent();
		onLeave(position);
	}

	private void onLeave(int position) {
		TabFragment fragment = getFragmentByPosition(lastPostion);
		lastPostion = position;
		// INSTANCE
		if (fragment == null) {
			return;
		}
		fragment.onLeave();
	}

	public void onPageScrolled(int position) {
		TabFragment fragment = getFragmentByPosition(position);

		// INSTANCE
		if (fragment == null) {
			return;
		}

		fragment.onCurrentScrolled();
		onLeave(position);
	}

	private TabFragment getFragmentByPosition(int position) {
		// IDX
		if (position < 0 || position >= fragments.length) {
			return null;
		}
		return fragments[position];
	}

	@Override
	public void onCurrentTabClicked(int position) {

		TabFragment fragment = getFragmentByPosition(position);

		// INSTANCE
		if (fragment == null) {
			return;
		}

		fragment.onCurrentTabClicked();
	}

	@Override
	public void onCurrentTabDoubleTap(int position) {
		TabFragment fragment = getFragmentByPosition(position);

		// INSTANCE
		if (fragment == null) {
			return;
		}

		fragment.onCurrentTabDoubleTap();
	}
}