底部导航不起作用.如何解决此问题?

Question

我已经制作了代码来执行此操作，它在单击底部导航中的项目时加载片段，但是当我单击它时它们不起作用。我尝试了很多次检查问题所在，即使Android Studio找不到它，因为应用程序无法正常工作。我不知道是什么问题。

我的主要活动 -

public class MainActivity extends AppCompatActivity {
BottomNavigationView btm_view;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = manager.beginTransaction();
fragmentTransaction.add(R.id.container, new Chats());
fragmentTransaction.commit();
btm_view = findViewById(R.id.bottom_view);
btm_view.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
if (item.getItemId() == R.id.camera) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = manager.beginTransaction();
fragmentTransaction.add(R.id.container, new Camera());
fragmentTransaction.commit();
} else if (item.getItemId() == R.id.chats) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = manager.beginTransaction();
fragmentTransaction.add(R.id.container, new Chats());
fragmentTransaction.commit();
} else if (item.getItemId() == R.id.status) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = manager.beginTransaction();
fragmentTransaction.add(R.id.container, new Status());
fragmentTransaction.commit();
} else if (item.getItemId() == R.id.calls) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = manager.beginTransaction();
fragmentTransaction.add(R.id.container, new Calls());
fragmentTransaction.commit();
} else if (item.getItemId() == R.id.settings) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = manager.beginTransaction();
fragmentTransaction.add(R.id.container, new Settings());
fragmentTransaction.commit();
}
return false;
}
});
}
}

我的一个片段——

public class Chats extends Fragment {
public Chats() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_chats, container, false);
}
}

Answer 1

试试这种方式

BottomNavigationView.OnNavigationItemSelectedListener navigationItemSelectedListener =
new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.chats:
openFragment(Chat.newInstance());
return true;
case R.id.camera:
openFragment(Camera.newInstance());
return true;
case R.id.status:
openFragment(Status.newInstance("", ""));
return true;
}
return false;
}
};

Answer 2

• 第一次使用replace(R.id.container, fragment)而不是add。
• 优化代码

利用setOnNavigationItemSelectedListener.试试这种方式

设置在底部导航项为时将收到通知的侦听器 选择。

btm_view.setOnNavigationItemSelectedListener(navigationItemSelectedListener);
openFragment(Camera.newInstance());
}
public void openFragment(Fragment fragment) {
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
transaction.commit();
}
BottomNavigationView.OnNavigationItemSelectedListener navigationItemSelectedListener =
new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override public boolean onNavigationItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.camera:
openFragment(Camera.newInstance());
return true;
case R.id.chats:
openFragment(Chats.newInstance());
return true;
case R.id.status:
openFragment(Status.newInstance());
return true;
case R.id.calls:
openFragment(Calls.newInstance());
return true;
case R.id.settings:
openFragment(Settings.newInstance());
return true;
}
return false;
}
};
}

您的聊天片段将是

public class Chats extends Fragment {
public Chats() {
// Required empty public constructor
}
public static Chats newInstance() {
Chats fragment = new Chats();
return fragment;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_chats, container, false);
}
}