使用导航抽屉显示片段

Question

I'm confused how to open my different fragments by clicking on one Item in my navigation drawer.

In MainActivity I use the following Code:

 @SuppressWarnings("StatementWithEmptyBody") @Override public boolean onNavigationItemSelected(MenuItem item) { Fragment fragment; int id = item.getItemId(); if (id == R.id.nav_listview) { FragmentTransaction ft = getSupportFragmentManager().beginTransaction(); ft.replace(R.id.fragment, new ListFragment()); ft.commit(); } else if (id == R.id.nav_add_data) { } else if (id == R.id.nav_settings) { } else if (id == R.id.nav_legal_information) { } DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); drawer.closeDrawer(GravityCompat.START); return true; } 

First of all I want to try to open my ListFragment:

 import android.os.Bundle; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; public class ListFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { return inflater.inflate(R.layout.fragment_list, container, false); } } 

In my content main.xml I created the following fragment which should be replaced when clicking on the specific Items in the Navigation Drawer.

  <fragment android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/fragment" /> 

But it isnt working...

Can anyone help me?

Rastaman

Answer 1

To get what you want try this ,I was also held up with this somewhat complex looking code but its more of a easy way to use

Here's detailed explanation and walk through to this issue: (Its seems Long But You can easily relate your work asap)

When you first create the Navigation Drawer Activity, there are 5 files we'll look at:

• MainActivity.java - this is the code behind for everything in our app.
• activity_main.xml - this is the layout for the app including the nav drawer and an include for the app_bar_main.
• app_bar_main.xml - this is the layout with the toolbar (at the top), a floating action button (at the bottom right), and an include for content_main.
• content_main.xml - this is the layout for the content of the main page.
• nav_header_main.xml - this is the UI for the top part of the nav drawer.

Step 1: open up the app_bar_main.xml , comment out the include and add a new FrameLayout:

<!--<include layout="@layout/content_main" />-->

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

This FrameLayout is what we'll use to load our fragments into.

Step 2: Next, you'll want to add a few fragments To do so, right click on your project, or go to File –> New and from the Fragment list choose Fragment (Blank) or others

Step 3: The next step is to load a fragment when the app first launches. Go to the MainActivity ’s onCreate method and put the following in after the call to setSupportActionBar :

Fragment fragment = null;
Class fragmentClass = null;
fragmentClass = FragmentOne.class;
try {
    fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {
    e.printStackTrace();
}

FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.Fragment_container, fragment).commit();

Step 4:

You'll then need to add OnFragmentInteractionListener to the interfaces your MainActivity implements and also implement the onFragmentInteraction method.Like this

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener, FragmentOne.OnFragmentInteractionListener ,FragmentTwo.OnFragmentInteractionListener,FragmentThree.OnFragmentInteractionListener {

Step 5: Finally, in the onNavigationItemSelected method, you can add the ability to load different fragments when menu items are tapped:

public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();
    Fragment fragment = null;
    Class fragmentClass = null;
    if (id == R.id.nav_camera) {
        fragmentClass = FragmentOne.class;
    } else if (id == R.id.nav_gallery) {
        fragmentClass = FragmentTwo.class;
    } else if (id == R.id.nav_slideshow) {
        fragmentClass = FragmentThree.class;
    } else if (id == R.id.nav_manage) {

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

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

    }
    try {
        fragment = (Fragment) fragmentClass.newInstance();
    } catch (Exception e) {
        e.printStackTrace();
    }
    FragmentManager fragmentManager = getSupportFragmentManager();
    fragmentManager.beginTransaction().replace(R.id.flContent, fragment).commit();

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

Here I'm just loading one of the two fragments I've added to my app. Note that because I have two different fragments, I had to implement the interfaces for both FragmentOne.OnFragmentInteractionListener and FragmentTwo.OnFragmentInteractionListener.

That's all you need to do to implement fragment loading in your Navigation Drawer. What the user taps a menu item, the drawer will slide back in smoothly and the new fragment will have already started / finished loading. This also prevents any possible jankiness that you could see when launching a new activity.

EXTRA One last thing to note is that if you switch to a different fragment and then rotate the device or cause another recreation of the activity, the code above will cause the first fragment to be reloaded. One easy way to deal with that is to wrap the fragment block in the onCreate method in a check to see if the savedInstanceState is not null like this:

protected void onCreate(Bundle savedInstanceState) {
    ...
    if (savedInstanceState == null) {
        //Fragment load code
    }
    ...
}

Answer 2

Try this Code

 @SuppressWarnings("StatementWithEmptyBody") @Override public boolean onNavigationItemSelected(MenuItem item) { Fragment fragment=null; FragmentTransaction ft = getSupportFragmentManager().beginTransaction(); int id = item.getItemId(); if (id == R.id.nav_listview) { fragment= new ListFragment(); } else if (id == R.id.nav_add_data) { } else if (id == R.id.nav_settings) { } else if (id == R.id.nav_legal_information) { } ft.replace(R.id.container, fragment); ft.addToBackStack(null); ft.commit(); DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); drawer.closeDrawer(GravityCompat.START); return true; } 

  <FrameLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/container" /> 

Answer 3

Mhmm I found an answer. But I am confused. If I use:

  if (id == R.id.nav_listview) { fragment= new com.thomas.testapp.ListFragment(); 

It works. But I only have to use the package name if I want to open my ListFragment. Why?

Answer 4

请更改您的片段类ListFragment的名称，因为ListFragment已经是android.app 包 android OS中的Fragments的子类

Answer 5

I suggest to Create codes More Dynamic

first of all, if you have custom class to create Navigation Drawer, use listener to call methods from your activity there is class call HomeFragment extends Fragment, so we have :

if(condition){
    fragment = new HomeFragment();
    // if there is Listener
    if(mListener != null){
        mListener.someMethod
    }
    // Other Settings And Codes
}

Answer 6

public class MainActivity extends AppCompatActivity {



// ...



@Override

protected void onCreate(Bundle savedInstanceState) {

    // ...From section above...

    // Find our drawer view

    nvDrawer = (NavigationView) findViewById(R.id.nvView);

    // Setup drawer view

    setupDrawerContent(nvDrawer);

}



private void setupDrawerContent(NavigationView navigationView) {

    navigationView.setNavigationItemSelectedListener(

            new NavigationView.OnNavigationItemSelectedListener() {

                @Override

                public boolean onNavigationItemSelected(MenuItem menuItem) {

                    selectDrawerItem(menuItem);

                    return true;

                }

            });

}



public void selectDrawerItem(MenuItem menuItem) {

    // Create a new fragment and specify the fragment to show based on nav item clicked

    Fragment fragment = null;

    Class fragmentClass;

    switch(menuItem.getItemId()) {

        case R.id.nav_first_fragment:

            fragmentClass = FirstFragment.class;

            break;

        case R.id.nav_second_fragment:

            fragmentClass = SecondFragment.class;

            break;

        case R.id.nav_third_fragment:

            fragmentClass = ThirdFragment.class;

            break;

        default:

            fragmentClass = FirstFragment.class;

    }



    try {

        fragment = (Fragment) fragmentClass.newInstance();

    } catch (Exception e) {

        e.printStackTrace();

    }



    // Insert the fragment by replacing any existing fragment

    FragmentManager fragmentManager = getSupportFragmentManager();

    fragmentManager.beginTransaction().replace(R.id.flContent, fragment).commit();



    // Highlight the selected item has been done by NavigationView

    menuItem.setChecked(true);

    // Set action bar title

    setTitle(menuItem.getTitle());

    // Close the navigation drawer

    mDrawer.closeDrawers();

}



// ...

}