ActionBar错误“不兼容的类型”

Question

我很难使用ActionBar制作标签。当我通过一些代码更改来运行应用程序时，我的应用程序立即崩溃，甚至没有启动。当前代码最接近我可以获得的工作。这是MainActivity：

import android.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.view.Menu;
import android.support.v4.app.FragmentActivity;
import android.support.v7.app.ActionBar.Tab;
import android.app.ActionBar;

public class MainActivity extends FragmentActivity implements ActionBar.TabListener {

    ActionBar actionbar;
    ViewPager viewpager;
    FragmentPageAdapter ft;
    FragmentPageAdapter mAdapter;

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

        viewpager = (ViewPager) findViewById(R.id.pager);
        ft = new FragmentPageAdapter(getSupportFragmentManager());
        mAdapter = new FragmentPageAdapter(getSupportFragmentManager());
        //final ActionBar actionBar = getActionBar();
        //final ActionBar actionBar = getSupportActionBar();

        actionbar = getActionBar();

        viewpager.setAdapter(ft);
        actionbar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        actionbar.addTab(actionbar.newTab().setText("DotNet").setTabListener(this));
        actionbar.addTab(actionbar.newTab().setText("Eal").setTabListener(this));
        actionbar.addTab(actionbar.newTab().setText("Neowin").setTabListener(this));
        actionbar.addTab(actionbar.newTab().setText("PcWorld").setTabListener(this));
        viewpager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageSelected(int arg0) {
                actionbar.setSelectedNavigationItem(arg0);
            }
            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {
                // TODO Auto-generated method stub
            }
            @Override
            public void onPageScrollStateChanged(int arg0) {
                // TODO Auto-generated method stub
            }
        });
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
            // TODO Auto-generated method stub
    }

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



    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
            // TODO Auto-generated method stub
    }


    @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;
    }
}