小编Art*_*ley的帖子

所以我遇到了这个问题.我正在尝试使用一些tabs制作简单的操作栏.我正在获取NullPointerException并且我无法弄清楚如何修复它.这是一些代码:

MainActivity.java

public class MainActivity extends FragmentActivity {
    ViewPager Tab;
    TabPagerAdapter TabAdapter;
    ActionBar actionBar;
    PagerSlidingTabStrip tabs;

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

        tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
        Tab = (ViewPager) findViewById(R.id.pager);
        TabAdapter = new TabPagerAdapter(getSupportFragmentManager());

        Tab.setAdapter(TabAdapter);
        tabs.setViewPager(Tab); //line 27 where the error appears

        tabs.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {

                actionBar = getActionBar();
                actionBar.setSelectedNavigationItem(position);
            }
        });
    }
}

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <com.astuetz.PagerSlidingTabStrip
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="48dip" />

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent" …