活动开始时加载片段

Question

我正在按照一个博客的教程来创建片段。我创建了三个片段，但是当 Mainactivity 加载时......它是空的，并且只有当单击抽屉菜单中的任何项目时，才会加载片段。我想在开始时加载任何片段[考虑 ConnectFragment]。

这是我的代码

public class MainActivity extends AppCompatActivity {

    private String[] mNavigationDrawerItemTitles;

    private DrawerLayout mDrawerLayout;

    private ListView mDrawerList;

    Toolbar toolbar;

    private CharSequence mDrawerTitle;

    private CharSequence mTitle;

    android.support.v7.app.ActionBarDrawerToggle mDrawerToggle;

    Fragment fragment = null;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        mTitle = mDrawerTitle = getTitle();

        mNavigationDrawerItemTitles= getResources().getStringArray(R.array.navigation_drawer_items_array);

        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);

        mDrawerList = (ListView) findViewById(R.id.left_drawer);

        setupToolbar();

        fragment = new ConnectFragment();

        DataModel[] drawerItem = new DataModel[3];

        drawerItem[0] = new DataModel(R.drawable.connect, "Connect");

        drawerItem[1] = new DataModel(R.drawable.fixtures, "Fixtures");

        drawerItem[2] = new DataModel(R.drawable.table, "Table");

        getSupportActionBar().setDisplayHomeAsUpEnabled(false);

        getSupportActionBar().setHomeButtonEnabled(true);

        DrawerItemCustomAdapter adapter = new DrawerItemCustomAdapter(this, R.layout.list_view_item_row, drawerItem);

        mDrawerList.setAdapter(adapter);

        mDrawerList.setOnItemClickListener(new DrawerItemClickListener());

        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);

        mDrawerLayout.setDrawerListener(mDrawerToggle);

        setupDrawerToggle();

    }

我尝试过

            fragment = new ConnectFragment();

但它仍然在开始时不加载。

提前致谢。

Answer 1

不需要创建fragment实例，onCreate您可以删除以下行fragment = new ConnectFragment();简而言之，您应该像下面这样调用selectItem()内部方法。onCreate()@Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        // .....        setupDrawerToggle();        // here you need call selectItem() method         selectItem(0) // you can change default fragment by changing parameter (0/1/2) as you want    }