小编Per*_*aSH的帖子

我正在尝试使用android材料设计实现滑动标签布局.但它给了我NullPointerException.到目前为止,这是我的代码:

MainActivity.java

public class MainActivity extends ActionBarActivity {
    private Toolbar toolbar;
    private ViewPager pager;
    private SlidingTabLayout nLayout;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main_appbar);
        toolbar = (Toolbar) findViewById(R.id.app_bar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayShowHomeEnabled(true);

        NavigationDrawerFragment drawerFragment = (NavigationDrawerFragment)
                getSupportFragmentManager().findFragmentById(R.id.navigation_drawer_fragment);
        drawerFragment.setUp(R.id.navigation_drawer_fragment, (DrawerLayout) findViewById(R.id.drawer_layout), toolbar);
        pager = (ViewPager) findViewById(R.id.pager);
        pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));

        nLayout = (SlidingTabLayout) findViewById(R.id.tabs);
        nLayout.setViewPager(pager);
    }

    @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;
    } …