Android更好地实现导航片段

Question

我有一个导航视图和绘制我的应用程序的布局，我使用片段之间切换视图。我现在有它实现这样的，它工作正常：

app_bar_main.xml：

<LinearLayout 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:orientation="vertical"> 

     <android.support.design.widget.AppBarLayout 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:theme="@style/AppTheme.AppBarOverlay"> 

      <android.support.v7.widget.Toolbar 
       android:id="@+id/toolbar" 
       android:layout_width="match_parent" 
       android:layout_height="?attr/actionBarSize" 
       android:background="?attr/colorPrimary" 
       app:popupTheme="@style/AppTheme.PopupOverlay" /> 

     </android.support.design.widget.AppBarLayout> 

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

我设置的初始片段时，在我的MainActivity类的onCreate应用程序第一次启动：

public class MainActivity extends AppCompatActivity 
     implements NavigationView.OnNavigationItemSelectedListener { 

    //Provide global access to navigationview and toolbar 
    NavigationView navigationView = null; 
    Toolbar toolbar = null; 

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

     //Set initial fragment 
     NewFragment fragment = new NewFragment(); 
     android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 
     fragmentTransaction.replace(R.id.fragment_container, fragment); 
     fragmentTransaction.commit(); 
... 

当用户选择一个菜单项时，我设置了这样的换出片段：

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

     if (id == R.id.nav_new) { 
      NewFragment fragment = new NewFragment(); 
      android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 
      fragmentTransaction.replace(R.id.fragment_container, fragment); 
      fragmentTransaction.commit(); 
     } else if (id == R.id.nav_start) { 
      StartFragment fragment = new StartFragment(); 
      android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 
      fragmentTransaction.replace(R.id.fragment_container, fragment); 
      fragmentTransaction.commit(); 
... 

我觉得我在初始片段集以及if语句中有很多冗余代码

什么是更好的方式来压缩代码并换出片段而不会像这样重复？

Answer 1

可以拨打导航抽屉这些方法只是你的片段

@Override 
     public boolean onNavigationItemSelected(MenuItem item) { 
      int id = item.getItemId(); 
      if (id == R.id.search_near) { 
       addNewFragmentWithBackStack(new FragmentOne()); 
      }else if(.....){ 
       addNewFragmentWithBackStack(new FragmentTwo()); 
      } 
      DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
      drawer.closeDrawer(GravityCompat.START); 
      return true; 

    } 

的新对象对于堆栈中

public void addNewFragmentWithBackStack(Fragment fragment) { 
    if (fragment != null) { 
     FragmentManager fragmentManager = getSupportFragmentManager(); 
     FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); 
     fragmentTransaction.replace(R.id.mainContent, fragment, fragment.getClass().getSimpleName()) 
       .addToBackStack(fragment.getClass().getSimpleName()) 
       .commit(); 
    } else { 
    } 
} 

Answer 2

您可以如下创建一个函数，并传递一个片段对象作为参数：

private void launchActivity(Fragement fragment) 
{ 
    android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 
    fragmentTransaction.replace(R.id.fragment_container, fragment); 
    fragmentTransaction.commit(); 
} 

现在只需创建一个对象，然后调用这个函数你需要的地方。它会避免重复的代码。