TabListener.java

package com.pinecone.technology.mcommerce.learning.android.chaptor09.dataloader;

import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;

public class TabListener<T extends Fragment> implements ActionBar.TabListener {

	private final Activity mActivity;
	private final String mTag;
	private final Class<T> mClass;
	private Fragment mFragment;

	public TabListener(Activity activity, String tag, Class<T> clz) {
		mActivity = activity;
		mTag = tag;
		mClass = clz;
	}

	@Override
	public void onTabReselected(Tab tab, FragmentTransaction ft) {
		// TODO Auto-generated method stub

	}

	@Override
	public void onTabSelected(Tab tab, FragmentTransaction ft) {
		// TODO Auto-generated method stub
		// Check if the fragment is already initialized
        if (mFragment == null) {
            // If not, instantiate and add it to the activity
            mFragment = Fragment.instantiate(mActivity, mClass.getName());
            ft.add(android.R.id.content, mFragment, mTag);
        } else {
            // If it exists, simply attach it in order to show it
            ft.attach(mFragment);
        }
	}

	@Override
	public void onTabUnselected(Tab tab, FragmentTransaction ft) {
		// TODO Auto-generated method stub
		if (mFragment != null) {
            // Detach the fragment, because another one is being attached
            ft.detach(mFragment);
        }
	}

}