1 package com.example.navigationdemo;
 2 
 3 
 4 import android.os.Bundle;
 5 
 6 import androidx.annotation.NavigationRes;
 7 import androidx.annotation.Nullable;
 8 import androidx.fragment.app.Fragment;
 9 import androidx.navigation.NavController;
10 import androidx.navigation.Navigation;
11 
12 import android.view.LayoutInflater;
13 import android.view.View;
14 import android.view.ViewGroup;
15 import android.widget.Button;
16 
17 
18 /**
19  * A simple {@link Fragment} subclass.
20  */
21 public class HomeFragment extends Fragment {
22 
23 
24     public HomeFragment() {
25         // Required empty public constructor
26     }
27 
28 
29     @Override
30     public View onCreateView(LayoutInflater inflater, ViewGroup container,
31                              Bundle savedInstanceState) {
32         // Inflate the layout for this fragment
33         return inflater.inflate(R.layout.fragment_home, container, false);
34     }
35 
36     @Override
37     public void onActivityCreated(@Nullable Bundle savedInstanceState) {
38         super.onActivityCreated(savedInstanceState);
39         Button button;
40         button=getView().findViewById(R.id.button);
41         button.setOnClickListener(new View.OnClickListener() {
42             @Override
43             public void onClick(View v) {
44                 //找到button 所归属的Controller
45                 NavController controller= Navigation.findNavController(v);
46                 controller.navigate(R.id.action_homeFragment_to_detailFragment);
47             }
48         });
49 
50     }
51 }

 1 package com.example.navigationdemo;
 2 
 3 
 4 import android.os.Bundle;
 5 
 6 import androidx.annotation.Nullable;
 7 import androidx.fragment.app.Fragment;
 8 import androidx.navigation.Navigation;
 9 
10 import android.view.LayoutInflater;
11 import android.view.View;
12 import android.view.ViewGroup;
13 import android.widget.Button;
14 
15 
16 /**
17  * A simple {@link Fragment} subclass.
18  */
19 public class DetailFragment extends Fragment {
20 
21 
22     public DetailFragment() {
23         // Required empty public constructor
24     }
25 
26 
27     @Override
28     public View onCreateView(LayoutInflater inflater, ViewGroup container,
29                              Bundle savedInstanceState) {
30         // Inflate the layout for this fragment
31         return inflater.inflate(R.layout.fragment_detail, container, false);
32     }
33 
34     @Override
35     public void onActivityCreated(@Nullable Bundle savedInstanceState) {
36         super.onActivityCreated(savedInstanceState);
37         //Button button;
38         getView().findViewById(R.id.button2).setOnClickListener(Navigation.createNavigateOnClickListener(R.id.action_detailFragment_to_homeFragment));
39     }
40 }

 1 package com.example.navigationdemo;
 2 
 3 import androidx.appcompat.app.AppCompatActivity;
 4 import androidx.navigation.NavController;
 5 import androidx.navigation.Navigation;
 6 import androidx.navigation.ui.NavigationUI;
 7 
 8 import android.os.Bundle;
 9 
10 public class MainActivity extends AppCompatActivity {
11 
12     @Override
13     protected void onCreate(Bundle savedInstanceState) {
14         super.onCreate(savedInstanceState);
15         setContentView(R.layout.activity_main);
16         //创建返回键 左上角
17         NavController controller= Navigation.findNavController(this,R.id.fragment);
18         NavigationUI.setupActionBarWithNavController(this,controller);
19     }
20     //实现返回功能
21     @Override
22     public boolean onSupportNavigateUp() {
23         NavController controller=Navigation.findNavController(this,R.id.fragment);
24         return controller.navigateUp();
25         //return super.onSupportNavigateUp();
26     }
27 }