在导航抽屉中实现活动而不是片段

Question

I have been working on this nav drawer with activites. I have a couple of activites in my projects that i want to switch between using the nav drawer. So far I have achieved this

1. Create Nav drawer and Write some activities code.

2. Show same nav drawer in all activities.

3. Start a default activity when app starts.

But now my issue is that when i open my app for first time, it loads my desired activity and i can see this nav drawer. when i switch activity and press the back button, I'm getting this blank activity with nav drawer. I know its some kinda beginner level issue. But please if someone can suggest the edit. Here is my code.

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

NavigationView navigationView = null;
Toolbar toolbar = null;
DrawerLayout drawer;
FrameLayout frameLayout;

private static boolean isLaunch = true;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    frameLayout = (FrameLayout) findViewById(R.id.contant_frame);
    drawer = (DrawerLayout) findViewById(R.id.drawer_layout);

    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, "", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    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);

    if (isLaunch) {
        isLaunch = false;
        startActivity(new Intent (this,MyAct.class));
    }

}

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

        startActivity(new Intent(this,About.class));

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

        startActivity(new Intent(this,About.class));

    }

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

}

I ve this same app working perfect in simple listview type nav drawer. but now im trying to implement fancy material design.

Answer 1

尝试覆盖onBackButtonPressed方法。

Answer 2

Clearing/removing the onBackpressed method in MyAct and About class will bring back the last view with anything that was populated.

But if you want to open some other view or want to start new activity when back key is pressed, you can add your code here in this onBackPressed method

Hope it helps. Cheers!