点击侧滑菜单选项切换fragment

1.布局

外层是DrawerLayout 

<android.support.v4.widget.DrawerLayout 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"
    android:id="@+id/dl"
    tools:context=".MainActivity">

    <LinearLayout
        android:id="@+id/ll"
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:minHeight="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"></android.support.v7.widget.Toolbar>

        <FrameLayout
            android:id="@+id/fg"
            android:layout_width="match_parent"
            android:layout_height="match_parent"></FrameLayout>
    </LinearLayout>


    <android.support.design.widget.NavigationView
        android:id="@+id/nv"
        android:layout_gravity="left"
        app:headerLayout="@layout/activity_header"
        app:menu="@menu/nv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></android.support.design.widget.NavigationView>

</android.support.v4.widget.DrawerLayout>

2.主要中

@Override
    protected void initView() {
        mToolbar.setTitle("首页");
        manager = getSupportFragmentManager();
        setSupportActionBar(mToolbar);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, mDl, mToolbar, R.string.about, R.string.about);
        mDl.addDrawerListener(toggle);
        toggle.syncState();


        initFragment();
        addFragment();
    }

    private void addFragment() {
        FragmentTransaction transaction = manager.beginTransaction();
        transaction.add(R.id.fg, list.get(0));
        transaction.commit();
    }
//自己创建fragmt
    private void initFragment() {
        list = new ArrayList<>();
        list.add(new HomeFragment());
        list.add(new CollectionFragment());
        list.add(new SettingFragment());
        list.add(new AboutFragment());
    }

    @Override
    protected void initListener() {
        mNv.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
                switch (menuItem.getItemId()) {
                    case R.id.wan:
                        switchFragment(HOME);
                        break;
                    case R.id.collection:
                        switchFragment(COLLECTION);
                        break;
                    case R.id.setting:
                        switchFragment(SETTING);
                        break;
                    case R.id.about:
                        switchFragment(ABOUT);
                        break;
                }
                mDl.closeDrawer(Gravity.LEFT);
                return false;
            }
        });
    }


    int HOME = 0;
    int COLLECTION = 1;
    int SETTING = 2;
    int ABOUT = 3;
    int LASTPOSITION = 0;


    private void switchFragment(int position) {
        FragmentTransaction transaction = manager.beginTransaction();
        Fragment fragment = list.get(position);
        if (!fragment.isAdded()) {
            transaction.add(R.id.fg, fragment);
        }
        Fragment lastfragment = list.get(LASTPOSITION);
        transaction.hide(lastfragment);
        transaction.show(fragment);
        transaction.commit();
        LASTPOSITION = position;
    }