Android 使用导航抽屉未显示片段

我正在使用导航抽屉显示我的应用程序中的一些片段。 不知何故，我无法使用片段容器使它们在MainActivity中可见。 也许我忽略了什么，有人能帮忙吗

先谢谢你

MainActivity java：

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;


public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

    NavigationView navigationView = null;
    Toolbar toolbar = null;

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

        // Set the fragment initially

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

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

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
        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);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        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) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
//        if (id == R.id.action_settings) {
//            return true;
//        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_camera) {
            // Set the fragment initially
            MainFragment fragment = new MainFragment();
            FragmentTransaction transaction =
                    getSupportFragmentManager().beginTransaction();
            transaction.replace(R.id.fragment_container, fragment);
            transaction.commit();
            // Handle the camera action
        } else if (id == R.id.nav_gallery) {
            // Set the fragment initially
            FactuurFragment fragment = new FactuurFragment();
            FragmentTransaction transaction =
                    getSupportFragmentManager().beginTransaction();
            transaction.replace(R.id.fragment_container, fragment);
            transaction.commit();

        } else if (id == R.id.nav_slideshow) {

        } else if (id == R.id.nav_manage) {

        } else if (id == R.id.nav_share) {

        } else if (id == R.id.nav_send) {

        }

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

带有片段容器的App_bar_main.xml：

编辑： Activity_Main.xml：

---

一切正常，除了你的片段内容留在工具栏后面，你看不到它。在顶部添加一个带有操作栏大小的边距，您将看到按钮

android:layout_marginTop="?android:attr/actionBarSize"

所以，就这样

<FrameLayout
            android:id="@+id/fragment_container"
            android:layout_width="match_parent"
            android:layout_marginTop="?android:attr/actionBarSize"
            android:layout_height="match_parent">

---

此外，我还将操作栏视图与主片段容器分开。将主片段容器移动到主活动布局。

一切正常，但片段内容留在工具栏后面，您看不到它。在顶部添加一个带有操作栏大小的边距，您将看到按钮

android:layout_marginTop="?android:attr/actionBarSize"

所以，就这样

<FrameLayout
            android:id="@+id/fragment_container"
            android:layout_width="match_parent"
            android:layout_marginTop="?android:attr/actionBarSize"
            android:layout_height="match_parent">

---

此外，我还将操作栏视图与主片段容器分开。将主片段容器移动到主活动布局。

检查此处，我们缺少您的主活动布局xml。请您发布活动_main.xml好吗？片段容器需要在其中。@arsent我发布了活动主目录，再次发送thx以获得帮助。检查这里我们缺少您的主活动布局xml。请您发布活动_main.xml好吗？碎片容器需要在里面。@arsent我发布了活动主目录，再次发送thx以获得帮助。Aaaa，1行代码。我怎么能忽视呢？许多thx阿森特，现在可以工作了。Aaaa，一行代码。我怎么能忽视呢？许多thx阿森特，现在起作用了。

android:layout_marginTop="?android:attr/actionBarSize"

<FrameLayout
            android:id="@+id/fragment_container"
            android:layout_width="match_parent"
            android:layout_marginTop="?android:attr/actionBarSize"
            android:layout_height="match_parent">