import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.viewpager.widget.ViewPager;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.MenuItem;
import android.view.View;
import android.view.WindowManager;
import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.google.firebase.auth.FirebaseAuth;
public class MainActivity extends AppCompatActivity {
BottomNavigationView bottomNavigationView;
Fragment selectedFragment = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try
{
this.getSupportActionBar().hide();
}
catch (NullPointerException e){}
setContentView(R.layout.activity_main);
bottomNavigationView = (BottomNavigationView)
findViewById(R.id.bottom_navigation);
bottomNavigationView.setOnNavigationItemSelectedListener(
new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.homee:
selectedFragment = new HomeFragment();
break;
case R.id.nav_search:
selectedFragment = new SearchFragment();
break;
case R.id.nav_notif:
selectedFragment = null;
startActivity(new Intent(MainActivity.this ,SearchFragment.class));
break;
}
if (selectedFragment != null){
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, selectedFragment).commit();
}
return true;
}
});
}
}
这都是我的主活动代码......我应该怎么做,才能让用户进入应用时默认打开主页片段,按照这个代码,当用户进入应用时,他需要按下主页按钮才能进入片段......我怎么能默认像例如instagram一样,用户一进来就把用户留在主页片段中,我怎么能这样做,我使用的是android材质的底部导航,如果你问我,我也可以提供这个活动的xml文件......谢谢你。
在你的MainActivity onCreate方法中试试这个。
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.fragment_container, new ExploreMainFragment());
ft.commit();
在你设置好之后,试试这段代码 setOnNavigationItemSelectedListener
bottomNavigationView.getMenu().findItem(R.id. homee).setChecked(true)