配置启动应用程序时首先显示的片段

问题描述

我创建了一个选项卡式活动，所以我已经做了很多事情.我跟随了一个教程，当单击一个抽屉项目时，将其更改为另一个片段.现在，在初始化应用程序时，我需要将 MainFragment 设置为默认值.我实际上不知道此刻正在发生什么.

I've created a tabbed activity, so many things are already done for me. I followed up a tutorial to, when clicking a drawer item, change to another fragment. Now, I need to, when initializing my app, for my MainFragment to be the default. I actually do not know what's showing up at the moment.

下面是负责处理片段更改的 MainActivity 的代码:

Below's the code of MainActivity that's responsible for handling the fragment change:

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);

        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);

        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

        return id == R.id.action_settings || super.onOptionsItemSelected(item);
    }

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
            case R.id.nav_home:
                setFragmentTransaction(new MainFragment(), "Dashboard");
                break;
            case R.id.nav_accounts:
                setFragmentTransaction(new AccountFragment(), "Accounts");
                break;
            case R.id.nav_categories:
                break;
            case R.id.nav_transactions:
                break;
            case R.id.nav_reports:
                break;
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);

       return true;
    }

    private void setFragmentTransaction(Fragment fragment, String title) {
        setTitle(title);

        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.fragment_container, fragment);
        transaction.commit();
    }
}

我尝试设置一个默认，但是它没有任何影响.

I tried setting up a default, but it didn't affect anything.

推荐答案

在 onCreate 的底部添加 setFragmentTransaction(new MainFragment()，"Dashboard"); .那应该加载您的主要片段.

Add setFragmentTransaction(new MainFragment(), "Dashboard"); to the bottom of onCreate. That should get your main fragment loaded.

这篇关于配置启动应用程序时首先显示的片段的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！