ListingActivity.java

package com.example.activity;

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.view.View;

import com.example.R;
import com.example.fragment.SimpleFragment;
import com.example.listener.OnDualPaneShowListener;


public class ListingActivity extends AppCompatActivity implements OnDualPaneShowListener
{
	private static final String SAVED_DUAL_PANE_FRAGMENT = "dual_pane_fragment";
	private static final String SAVED_DUAL_PANE_INDEX = "dual_pane_index";

	private boolean mDualPane;
	private Class<?> mDualPaneFragment = null;
	private int mDualPaneIndex = -1;


	@Override
	public void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_listing);

		// restore saved state
		if(savedInstanceState != null)
		{
			handleSavedInstanceState(savedInstanceState);
		}

		// handle dual pane layout
		handleDualPane();
	}


	@Override
	public void onSaveInstanceState(Bundle outState)
	{
		// save current instance state
		super.onSaveInstanceState(outState);
		if(mDualPaneFragment != null) outState.putString(SAVED_DUAL_PANE_FRAGMENT, mDualPaneFragment.getName());
		if(mDualPaneIndex != -1) outState.putInt(SAVED_DUAL_PANE_INDEX, mDualPaneIndex);
	}


	@Override
	public void onDualPaneShow(Class<?> targetFragment, int index)
	{
		mDualPaneFragment = targetFragment;
		mDualPaneIndex = index;

		if(mDualPane)
		{
			Fragment fragment = null;
			String tag = null;

			// type of fragment to be replaced
			if(targetFragment.equals(SimpleFragment.class))
			{
				fragment = SimpleFragment.newInstance(index);
				tag = SimpleFragment.class.getSimpleName();
			}

			// replace fragment
			if(fragment != null)
			{
				FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
				transaction.replace(R.id.container_dual_pane, fragment, tag);
				transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
				transaction.commit();
			}
		}
		else
		{
			Intent intent = null;

			// type of activity to be started
			if(targetFragment.equals(SimpleFragment.class))
			{
				intent = SimpleActivity.newIntent(this, index);
			}

			// start activity
			if(intent != null)
			{
				startActivity(intent);
			}
		}
	}


	private void handleSavedInstanceState(Bundle savedInstanceState)
	{
		String dualPaneFragmentString = savedInstanceState.getString(SAVED_DUAL_PANE_FRAGMENT);
		try
		{
			if(dualPaneFragmentString != null) mDualPaneFragment = Class.forName(dualPaneFragmentString);
		}
		catch(ClassNotFoundException e)
		{
			e.printStackTrace();
		}
		mDualPaneIndex = savedInstanceState.getInt(SAVED_DUAL_PANE_INDEX, -1);
	}


	private void handleDualPane()
	{
		// activity has dual pane layout
		View dualPaneContainer = findViewById(R.id.container_dual_pane);
		mDualPane = dualPaneContainer != null && dualPaneContainer.getVisibility() == View.VISIBLE;

		if(mDualPane && mDualPaneFragment != null && mDualPaneIndex != -1)
		{
			onDualPaneShow(mDualPaneFragment, mDualPaneIndex);
		}
	}
}