！slidingMenu的跳转有关问题

求助！slidingMenu的跳转问题！
我用了slidingMenu做出滑动显示左侧菜单， 在出来的菜单中设置跳转，但是为什么不跳转？
我是要从LiftNewsActivity 跳转到MainActivity类


java 代码 LiftNewsActivity类

public class LiftNewsActivity extends Activity implements OnClickListener {
	private RelativeLayout rl = null;
	private SlidingMenu slidingMenu = null;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.slidingmenu_left);
		rl= (RelativeLayout) findViewById(R.id.rlivtv1);
		rl.setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		// TODO Auto-generated method stub
		switch (v.getId()) {
		case R.id.rlivtv1:
			Intent intent = new Intent(LiftNewsActivity.this,MainActivity.class);
			startActivity(intent);
			break;
		}
	}

java 代码 MainActivity类

protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_main);
		timer = new Timer();

		findViewById(R.id.bNew).setOnClickListener(this);
		findViewById(R.id.bPersonal).setOnClickListener(this);
		((TextView) findViewById(R.id.tvTag1)).setOnClickListener(this);
		((TextView) findViewById(R.id.tvTag2)).setOnClickListener(this);
		((TextView) findViewById(R.id.tvTag3)).setOnClickListener(this);
		((TextView) findViewById(R.id.tvTag4)).setOnClickListener(this);

		views = new ArrayList<View>();
		views.add(LayoutInflater.from(this).inflate(R.layout.head_lines, null));
		views.add(LayoutInflater.from(this).inflate(R.layout.entertainment,
				null));
		views.add(LayoutInflater.from(this).inflate(R.layout.finance, null));
		views.add(LayoutInflater.from(this).inflate(R.layout.car, null));

		vpViewPager = (ViewPager) findViewById(R.id.vpViewPager1);
		vpViewPager.setAdapter(new MyPagerAdapter(views));
		// vpViewPager.setOnPageChangeListener(new MyOnPageChangeListener());

		// initCursor(views.size());

		// 设置抽屉菜单
		slidingMenu = new SlidingMenu(this);
		slidingMenu.setMode(SlidingMenu.LEFT_RIGHT);
		slidingMenu.setTouchModeAbove(SlidingMenu.TOUCHMODE_MARGIN); // 触摸边界拖出菜单
		slidingMenu.setMenu(R.layout.slidingmenu_left);
		slidingMenu.setSecondaryMenu(R.layout.slidingmenu_right);
		slidingMenu.setBehindOffsetRes(R.dimen.slidingmenu_offset);
		// 将抽屉菜单与主页面关联起来
		slidingMenu.attachToActivity(this, SlidingMenu.SLIDING_CONTENT);

		MyPagerAdapter myPagerAdapter = (MyPagerAdapter) vpViewPager
				.getAdapter();
		View v1 = myPagerAdapter.getItemAtPosition(0);
		View v2 = myPagerAdapter.getItemAtPosition(1);
		View v3 = myPagerAdapter.getItemAtPosition(2);
		View v4 = myPagerAdapter.getItemAtPosition(3);
		ptrlvHeadLineNews = (PullToRefreshListView) v1
				.findViewById(R.id.ptrlvHeadLineNews);
		ptrlvEntertainmentNews = (PullToRefreshListView) v2
				.findViewById(R.id.ptrlvEntertainmentNews);
		ptrlvFinanceNews = (PullToRefreshListView) v3
				.findViewById(R.id.ptrlvFinanceNews);
		ptrlvCarNews = (PullToRefreshListView) v4
				.findViewById(R.id.ptrlvCarNews);
		newAdapter = new NewListAdapter(this, getSimulationNews(10));
		initPullToRefreshListView(ptrlvHeadLineNews, newAdapter);
		initPullToRefreshListView(ptrlvEntertainmentNews, newAdapter);
		initPullToRefreshListView(ptrlvFinanceNews, newAdapter);
		initPullToRefreshListView(ptrlvCarNews, newAdapter);

	}

	@Override
	public void onBackPressed() {
		if (isExit) {
			finish();
		} else {
			isExit = true;
			Toast.makeText(MainActivity.this, "再按一次退出潍坊新闻", Toast.LENGTH_SHORT)
					.show();
			timeTask = new TimerTask() {

				@Override
				public void run() {
					isExit = false;
				}
			};
			timer.schedule(timeTask, 2000);
		}
	}

	@Override
	public void onClick(View v) {
		switch (v.getId()) {
		case R.id.tvTag1:
			vpViewPager.setCurrentItem(0);
			break;
		case R.id.tvTag2:
			vpViewPager.setCurrentItem(1);
			break;
		case R.id.tvTag3:
			vpViewPager.setCurrentItem(2);
			break;
		case R.id.tvTag4:
			vpViewPager.setCurrentItem(3);
			break;
		case R.id.bNew:
			slidingMenu.showMenu();
			break;
		case R.id.bPersonal:
			slidingMenu.showSecondaryMenu();
			break;
		}
	}

------解决思路----------------------
这个页面的跳转不是activity的跳转而是fragment的相互切换，需要用的是replace方法，而你用了intent，这是不可行的。你先了解下fragment再看看代码就明白了。我给你贴个我写的

//左侧导航栏点击事件
	public void menuItemClicked(int position) {
		menu.showContent();// 点击关闭
		switch (position) {
		case 0:
			Toast.makeText(getApplicationContext(), "遥信检测", 0).show();
			fragmentManager.beginTransaction()
					.replace(R.id.homefragment, new HomeFragment()).commit();
			break;
		case 1:
			Toast.makeText(getApplicationContext(), "遥控监测", 0).show();
			fragmentManager.beginTransaction()
					.replace(R.id.homefragment, new YaokongFragment()).commit();
			break;
		case 2:
			Toast.makeText(getApplicationContext(), "载波通信", 0).show();
			fragmentManager.beginTransaction()
					.replace(R.id.homefragment, new ZaibotongxinFragment())
					.commit();
			break;
		case 3:
			Toast.makeText(getApplicationContext(), "信号强度", 0).show();
			fragmentManager.beginTransaction()
					.replace(R.id.homefragment, new XinhaoqiangduFragment())
					.commit();
			break;
		case 4:
			Toast.makeText(getApplicationContext(), "电表抄读", 0).show();
			fragmentManager.beginTransaction()
					.replace(R.id.homefragment, new DianbiaochaoduFragment())
					.commit();
			break;
		case 5:
			Toast.makeText(getApplicationContext(), "脉冲检测", 0).show();
			fragmentManager.beginTransaction()
					.replace(R.id.homefragment, new MaichongjianceFragment())
					.commit();
			break;
		default:
			break;
		}