Question

我有一个导航抽屉，当我点击其中一个菜单时，我希望默认内容消失，但它不会发生，当我点击新菜单时它仍然存在。这真的很烦人，我一整天都试图寻找解决方案而且我现在已经疯了。

如果可以，请帮助我。提前谢谢！

我在这里复制整个代码。（p.s：这是我在Android上编程的第一次也是最后一次，这是一场噩梦......我现在必须这样做：/）

public class About extends AppCompatActivity {

private Toolbar toolbar;
private NavigationView navigationView;
private DrawerLayout drawerLayout;

ImageButton FAB;

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

    FAB = (ImageButton) findViewById(R.id.imageButton);
    FAB.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent i = new Intent(About.this, SecondActivity.class);
            startActivity(i);

            //FAB click, call other thing...

        }
    });

    navigationView = (NavigationView) findViewById(R.id.nav_view);

    FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
    fragmentTransaction.replace(R.id.content_frame, new ListViewFragment());
    fragmentTransaction.commit();

    setNavDrawer();
    navigationView.setCheckedItem(R.id.nav_gallery);
}
    private void setNavDrawer() {
    // Initializing Toolbar and setting it as the actionbar
    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    //Initializing NavigationView

    //Setting Navigation View Item Selected Listener to handle the item click of the navigation menu
    navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {

        // This method will trigger on item Click of navigation menu
        @Override
        public boolean onNavigationItemSelected(MenuItem menuItem) {


            //Checking if the item is in checked state or not, if not make it in checked state
            if (menuItem.isChecked()) menuItem.setChecked(false);
            else menuItem.setChecked(true);

            //Closing drawer on item click
            drawerLayout.closeDrawers();

            //Check to see which item was being clicked and perform appropriate action
            switch (menuItem.getItemId()) {


                //Replacing the main content with ContentFragment Which is our Inbox View;
                case R.id.nav_camera:
                    Toast.makeText(getApplicationContext(), "Clicked", Toast.LENGTH_SHORT).show();
                    ContentFragment fragment = new ContentFragment();
                    android.support.v4.app.FragmentTransaction f = getSupportFragmentManager().beginTransaction();
                    f.replace(R.id.content_frame, fragment);
                    f.commit();
                    return true;

                // For rest of the options we just show a toast on click

                case R.id.nav_gallery:
                    Toast.makeText(getApplicationContext(), "Whatever", Toast.LENGTH_SHORT).show();
                    UserFragment fragment2 = new UserFragment();
                    android.support.v4.app.FragmentTransaction f2 = getSupportFragmentManager().beginTransaction();
                    f2.replace(R.id.content_frame, fragment2);
                    f2.commit();
                    return true;
                case R.id.nav_slideshow:
                    Toast.makeText(getApplicationContext(), "SOON", Toast.LENGTH_SHORT).show();
                    return true;
                case R.id.nav_share:
                    Toast.makeText(getApplicationContext(), "SOON", Toast.LENGTH_SHORT).show();
                    return true;
                default:
                    Toast.makeText(getApplicationContext(), "SOON", Toast.LENGTH_SHORT).show();
                    return true;

            }
        }
    });


    drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this,drawerLayout,toolbar,R.string.navigation_drawer_open, R.string.navigation_drawer_close){

        @Override
        public void onDrawerClosed(View drawerView) {
            // Code here will be triggered once the drawer closes as we dont want anything to happen so we leave this blank
            super.onDrawerClosed(drawerView);
        }

        @Override
        public void onDrawerOpened(View drawerView) {
            // Code here will be triggered once the drawer open as we dont want anything to happen so we leave this blank

            super.onDrawerOpened(drawerView);
        }
    };

    //Setting the actionbarToggle to drawer layout
    drawerLayout.addDrawerListener(actionBarDrawerToggle);

    //calling sync state is necessay or else your hamburger icon wont show up
    actionBarDrawerToggle.syncState();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.about, 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);
  } 
}

Answer 1

在菜单上使用这些代码点击..

Fragment fragment = new ContentFragment();
            FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
            FragmentTransaction fragmentTransaction =        fragmentManager.beginTransaction();
            fragmentTransaction.replace(R.id.content_frame, fragment);
            fragmentTransaction.remove(new CurrentFragment());
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();

也可以在xml中添加这些行

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

Answer 2

试试这个

Fragment fragment = new Fragment();
fragment.setRetainInstance(true);
fragment = new ContentFragment ();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
               .replace(R.id.content_frame, fragment)
               .commit();

为什么setContentView在更改片段时不会消失

2 个答案: