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トップJavaに関する質問フラグメントのonReturnvalueを、アクティビティやフラグメントから実行したい

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回答編集履歴

3

コード修正

2022/04/14 11:58

投稿

jimbe
jimbe

スコア12659

test CHANGED
@@ -2,9 +2,13 @@
2
2
 
3
3
  例えば、会話風にダイアログを表示するとしますと、こんな感じに出来ます。
4
4
 
5
+ "NEXT" をクリックしなくても一定時間(4秒)で自動で進む "AUTOモード" を付けてみました。
6
+ ダイアログ左下の "AUTO-ON" / "AUTO-OFF" で切り替えられます。
7
+
5
8
  MainActivity.java
6
9
  ```java
7
10
  import android.os.Bundle;
11
+ import android.util.Log;
8
12
 
9
13
  import androidx.appcompat.app.AppCompatActivity;
10
14
  import androidx.fragment.app.FragmentManager;
@@ -19,6 +23,8 @@
19
23
  "B：建物は古いけど、安くていいよ。",
20
24
  "A：へー。"
21
25
  };
26
+ private static String REQUEST_KEY = "Conversation";
27
+ private static String DIALOG_TAG = "Dialog";
22
28
 
23
29
  @Override
24
30
  protected void onCreate(Bundle savedInstanceState) {
@@ -27,19 +33,22 @@
27
33
 
28
34
  FragmentManager fm = getSupportFragmentManager();
29
35
 
30
- fm.setFragmentResultListener("Conversation", this, (requestKey, result) -> {
36
+ fm.setFragmentResultListener(REQUEST_KEY, this, (requestKey, result) -> {
31
- int index = result.getInt(ConversationFragment.RESULT_INDEX);
37
+ int index = result.getInt(ConversationFragment.RESULT_NEXT_INDEX);
32
- index ++;
33
38
  if(index < conversation.length) {
34
- String positiveText = index == conversation.length-1 ? "終了" : "次へ";
39
+ boolean automode = result.getBoolean(ConversationFragment.RESULT_AUTOMODE);
35
- ConversationFragment dialog = ConversationFragment.createInstance("Conversation", conversation[index], index, positiveText);
40
+ ConversationFragment dialog = ConversationFragment.createInstance(REQUEST_KEY, conversation[index], index, conversation.length, automode);
36
- dialog.show(fm, "Conversation");
41
+ dialog.show(fm, DIALOG_TAG);
42
+ return;
37
43
  }
44
+
45
+ //会話が終わったらここに実行が来るので、終わった時の処理はここに書く
46
+ Log.d("MainActivity", "会話終了");
38
47
  });
39
48
 
40
- if(fm.findFragmentByTag("Conversation") == null) {
49
+ if(fm.findFragmentByTag(DIALOG_TAG) == null) {
41
- ConversationFragment dialog = ConversationFragment.createInstance("Conversation", conversation[0], 0, "次へ");
50
+ ConversationFragment dialog = ConversationFragment.createInstance(REQUEST_KEY, conversation[0], 0, conversation.length);
42
- dialog.show(fm, "Conversation");
51
+ dialog.show(fm, DIALOG_TAG);
43
52
  }
44
53
  }
45
54
  }
@@ -47,7 +56,9 @@
47
56
  ConversationFragment.java
48
57
  ```java
49
58
  import android.app.Dialog;
59
+ import android.content.DialogInterface;
50
- import android.os.Bundle;
60
+ import android.os.*;
61
+ import android.view.View;
51
62
 
52
63
  import androidx.annotation.*;
53
64
  import androidx.appcompat.app.AlertDialog;
@@ -57,17 +68,27 @@
57
68
  private static final String ARGS_REQUEST_KEY = "requestKey";
58
69
  private static final String ARGS_MESSAGE = "message";
59
70
  private static final String ARGS_INDEX = "index";
60
- private static final String ARGS_POSITIVE_TEXT = "positiveText";
71
+ private static final String ARGS_END_OF_INDEX = "endOfIndex";
72
+ private static final String ARGS_AUTOMODE = "automode";
61
73
 
62
- public static final String RESULT_INDEX = "index";
74
+ private static final int AUTOMODE_DELAY = 4000; //[ms]
63
75
 
76
+ public static final String RESULT_NEXT_INDEX = "nextIndex";
77
+ public static final String RESULT_AUTOMODE = "automode";
78
+
79
+ @NonNull
64
- static ConversationFragment createInstance(String requestKey, String message, int index, String positiveText) {
80
+ static ConversationFragment createInstance(@NonNull String requestKey, @NonNull String message, int index, int endOfIndex) {
81
+ return createInstance(requestKey, message, index, endOfIndex, false);
82
+ }
83
+ @NonNull
84
+ static ConversationFragment createInstance(@NonNull String requestKey, @NonNull String message, int index, int endOfIndex, boolean automode) {
65
85
  ConversationFragment fragment = new ConversationFragment();
66
86
  Bundle args = new Bundle();
67
87
  args.putString(ARGS_REQUEST_KEY, requestKey);
68
88
  args.putString(ARGS_MESSAGE, message);
69
89
  args.putInt(ARGS_INDEX, index);
70
- args.putString(ARGS_POSITIVE_TEXT, positiveText);
90
+ args.putInt(ARGS_END_OF_INDEX, endOfIndex);
91
+ args.putBoolean(ARGS_AUTOMODE, automode);
71
92
  fragment.setArguments(args);
72
93
  return fragment;
73
94
  }
@@ -77,17 +98,78 @@
77
98
  public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
78
99
  Bundle args = getArguments();
79
100
  String message = args.getString(ARGS_MESSAGE);
101
+ int index = args.getInt(ARGS_INDEX);
80
- String positiveText = args.getString(ARGS_POSITIVE_TEXT);
102
+ int endOfIndex = args.getInt(ARGS_END_OF_INDEX);
103
+
81
- return new AlertDialog.Builder(getContext())
104
+ AlertDialog dialog = new AlertDialog.Builder(getContext())
82
105
  .setMessage(message)
83
- .setPositiveButton(positiveText, (dialog, which) -> {
106
+ .setPositiveButton(index+1<endOfIndex ? "Next" : "End", (d, w) -> setFragmentResult(args, index+1, false))
84
- String requestKey = args.getString(ARGS_REQUEST_KEY);
85
- int index = args.getInt(ARGS_INDEX);
86
- Bundle result = new Bundle();
87
- result.putInt(RESULT_INDEX, index);
88
- getParentFragmentManager().setFragmentResult(requestKey, result);
107
+ .setNegativeButton("Skip", (d, w) -> setFragmentResult(args, endOfIndex, false))
89
- })
108
+ .setNeutralButton("-", null) //NEUTRALボタンを生成するためのダミー
90
109
  .create();
110
+
111
+ dialog.setOnShowListener(new AutomodeManager(args));
112
+
113
+ return dialog;
114
+ }
115
+
116
+ private class AutomodeManager implements DialogInterface.OnShowListener, View.OnClickListener {
117
+ private AlertDialog dialog;
118
+ private Bundle args;
119
+ private boolean automode;
120
+ private Handler handler;
121
+ private Runnable callback;
122
+
123
+ AutomodeManager(@NonNull Bundle args) {
124
+ this.args = args;
125
+ automode = args.getBoolean(ARGS_AUTOMODE);
126
+ handler = new Handler(requireActivity().getMainLooper());
127
+ }
128
+
129
+ @Override
130
+ public void onShow(DialogInterface dialog) {
131
+ this.dialog = (AlertDialog)dialog;
132
+ this.dialog.getButton(AlertDialog.BUTTON_NEUTRAL).setOnClickListener(this); //押してもダイアログがクローズしないように, 直接リスナを登録
133
+ setButtonsState();
134
+ if(automode) postClickEvent();
135
+ }
136
+
137
+ @Override
138
+ public void onClick(View view) {
139
+ automode = !automode;
140
+ setButtonsState();
141
+ if(automode) {
142
+ postClickEvent();
143
+ } else {
144
+ cancelClickEvent();
145
+ }
146
+ }
147
+
148
+ private void setButtonsState() {
149
+ dialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(!automode);
150
+ dialog.getButton(AlertDialog.BUTTON_NEGATIVE).setEnabled(!automode);
151
+ dialog.getButton(AlertDialog.BUTTON_NEUTRAL).setText(automode ? "Auto-OFF" : "Auto-ON");
152
+ }
153
+
154
+ private void postClickEvent() {
155
+ callback = () -> {
156
+ setFragmentResult(args, args.getInt(ARGS_INDEX)+1, true);
157
+ dialog.dismiss();
158
+ };
159
+ handler.postDelayed(callback, AUTOMODE_DELAY); //[ms]
160
+ }
161
+
162
+ private void cancelClickEvent() {
163
+ handler.removeCallbacks(callback);
164
+ }
165
+ }
166
+
167
+ private void setFragmentResult(@NonNull Bundle args, int nextIndex, boolean automode) {
168
+ String requestKey = args.getString(ARGS_REQUEST_KEY);
169
+ Bundle result = new Bundle();
170
+ result.putInt(RESULT_NEXT_INDEX, nextIndex);
171
+ result.putBoolean(RESULT_AUTOMODE, automode);
172
+ getParentFragmentManager().setFragmentResult(requestKey, result);
91
173
  }
92
174
  }
93
175
  ```

2

全面変更

2022/04/12 11:44

投稿

jimbe
jimbe

スコア12659

test CHANGED
@@ -1,225 +1,93 @@
1
- 表示中のフラグメントに対し別のフラグメントやアクティビティから値を渡すのであれば、 ViewModel を経由するのが妥当に思います。
1
+ ※コメントにより、趣旨が変わってしまいますが回答がごちゃごちゃになりそうですので書き直します。
2
+
3
+ 例えば、会話風にダイアログを表示するとしますと、こんな感じに出来ます。
2
4
 
3
5
  MainActivity.java
4
6
  ```java
5
7
  import android.os.Bundle;
6
- import android.widget.EditText;
7
8
 
8
9
  import androidx.appcompat.app.AppCompatActivity;
9
- import androidx.lifecycle.ViewModelProvider;
10
+ import androidx.fragment.app.FragmentManager;
10
11
 
11
12
  public class MainActivity extends AppCompatActivity {
13
+ private static final String conversation[] = {
14
+ "A：休みの日にどこか行きたいんですが、いいところありますか？",
15
+ "B：うーん、A さんはスポーツが好き？",
16
+ "A：はい。",
17
+ "B：××スポーツセンターとかはどう？",
18
+ "A：スポーツセンター？",
19
+ "B：建物は古いけど、安くていいよ。",
20
+ "A：へー。"
21
+ };
12
22
 
13
23
  @Override
14
24
  protected void onCreate(Bundle savedInstanceState) {
15
25
  super.onCreate(savedInstanceState);
16
26
  setContentView(R.layout.activity_main);
17
27
 
18
- SampleViewModel viewModel = new ViewModelProvider(this).get(SampleViewModel.class);
28
+ FragmentManager fm = getSupportFragmentManager();
19
29
 
20
- EditText editText = findViewById(R.id.editText);
21
- findViewById(R.id.setButton).setOnClickListener(v -> viewModel.setText(editText.getText().toString()));
30
+ fm.setFragmentResultListener("Conversation", this, (requestKey, result) -> {
31
+ int index = result.getInt(ConversationFragment.RESULT_INDEX);
32
+ index ++;
33
+ if(index < conversation.length) {
34
+ String positiveText = index == conversation.length-1 ? "終了" : "次へ";
35
+ ConversationFragment dialog = ConversationFragment.createInstance("Conversation", conversation[index], index, positiveText);
36
+ dialog.show(fm, "Conversation");
37
+ }
38
+ });
22
39
 
23
- getSupportFragmentManager().beginTransaction()
40
+ if(fm.findFragmentByTag("Conversation") == null) {
41
+ ConversationFragment dialog = ConversationFragment.createInstance("Conversation", conversation[0], 0, "次へ");
24
- .replace(R.id.fragment1, new AFragment())
42
+ dialog.show(fm, "Conversation");
25
- .replace(R.id.fragment2, new BFragment())
26
- .commit();
43
+ }
27
44
  }
28
45
  }
29
46
  ```
30
- res/layout/activity_main.xml
47
+ ConversationFragment.java
31
- ```xml
48
+ ```java
32
- <?xml version="1.0" encoding="utf-8"?>
33
- <androidx.constraintlayout.widget.ConstraintLayout
34
- xmlns:android="http://schemas.android.com/apk/res/android"
35
- xmlns:app="http://schemas.android.com/apk/res-auto"
36
- xmlns:tools="http://schemas.android.com/tools"
37
- android:layout_width="match_parent"
38
- android:layout_height="match_parent"
39
- tools:context=".MainActivity">
49
+ import android.app.Dialog;
50
+ import android.os.Bundle;
40
51
 
41
- <LinearLayout
42
- android:id="@+id/activity"
43
- android:layout_width="0dp"
52
+ import androidx.annotation.*;
44
- android:layout_height="wrap_content"
45
- android:orientation="vertical"
46
- android:background="#ff80ffff"
47
- app:layout_constraintLeft_toLeftOf="parent"
48
- app:layout_constraintRight_toLeftOf="@id/arrow"
49
- app:layout_constraintTop_toTopOf="parent">
50
- <TextView
51
- android:layout_width="match_parent"
53
+ import androidx.appcompat.app.AlertDialog;
52
- android:layout_height="wrap_content"
53
- android:text="ACTIVITY"
54
- android:textSize="20dp" />
55
- <EditText
56
- android:id="@+id/editText"
57
- android:layout_width="match_parent"
58
- android:layout_height="wrap_content"
59
- android:textSize="15dp"/>
54
+ import androidx.fragment.app.DialogFragment;
60
- <Button
61
- android:id="@+id/setButton"
62
- android:text="SET"
63
- android:layout_width="wrap_content"
64
- android:layout_height="wrap_content" />
65
- </LinearLayout>
66
55
 
67
- <LinearLayout
68
- android:id="@+id/fragment1"
56
+ public class ConversationFragment extends DialogFragment {
69
- android:layout_width="0dp"
70
- android:layout_height="wrap_content"
57
+ private static final String ARGS_REQUEST_KEY = "requestKey";
71
- android:orientation="vertical"
58
+ private static final String ARGS_MESSAGE = "message";
72
- app:layout_constraintLeft_toLeftOf="parent"
59
+ private static final String ARGS_INDEX = "index";
73
- app:layout_constraintRight_toRightOf="@id/activity"
60
+ private static final String ARGS_POSITIVE_TEXT = "positiveText";
74
- app:layout_constraintTop_toBottomOf="@id/activity" />
75
61
 
76
- <TextView
77
- android:id="@+id/arrow"
78
- android:text="＞"
79
- android:textSize="20dp"
80
- android:layout_width="wrap_content"
81
- android:layout_height="wrap_content"
82
- app:layout_constraintBottom_toBottomOf="@id/fragment1"
83
- app:layout_constraintLeft_toRightOf="@id/activity"
84
- app:layout_constraintRight_toLeftOf="@id/fragment2"
85
- app:layout_constraintTop_toTopOf="parent" />
62
+ public static final String RESULT_INDEX = "index";
86
63
 
87
- <LinearLayout
88
- android:id="@+id/fragment2"
89
- android:layout_width="0dp"
90
- android:layout_height="wrap_content"
91
- android:orientation="vertical"
92
- app:layout_constraintLeft_toRightOf="@id/arrow"
64
+ static ConversationFragment createInstance(String requestKey, String message, int index, String positiveText) {
93
- app:layout_constraintRight_toRightOf="parent"
94
- app:layout_constraintTop_toTopOf="parent" />
95
-
96
- </androidx.constraintlayout.widget.ConstraintLayout>
65
+ ConversationFragment fragment = new ConversationFragment();
97
- ```
98
- SampleViewModel.java
99
- ```java
100
- import androidx.lifecycle.*;
66
+ Bundle args = new Bundle();
101
-
102
- public class SampleViewModel extends ViewModel {
67
+ args.putString(ARGS_REQUEST_KEY, requestKey);
103
- private MutableLiveData<String> textLiveData = new MutableLiveData<>("init");
68
+ args.putString(ARGS_MESSAGE, message);
104
-
105
- LiveData<String> getText() {
69
+ args.putInt(ARGS_INDEX, index);
70
+ args.putString(ARGS_POSITIVE_TEXT, positiveText);
71
+ fragment.setArguments(args);
106
- return textLiveData;
72
+ return fragment;
107
73
  }
108
74
 
75
+ @NonNull
76
+ @Override
109
- void setText(String text) {
77
+ public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
110
- textLiveData.setValue(text);
78
+ Bundle args = getArguments();
79
+ String message = args.getString(ARGS_MESSAGE);
80
+ String positiveText = args.getString(ARGS_POSITIVE_TEXT);
81
+ return new AlertDialog.Builder(getContext())
82
+ .setMessage(message)
83
+ .setPositiveButton(positiveText, (dialog, which) -> {
84
+ String requestKey = args.getString(ARGS_REQUEST_KEY);
85
+ int index = args.getInt(ARGS_INDEX);
86
+ Bundle result = new Bundle();
87
+ result.putInt(RESULT_INDEX, index);
88
+ getParentFragmentManager().setFragmentResult(requestKey, result);
89
+ })
90
+ .create();
111
91
  }
112
92
  }
113
93
  ```
114
- AFragment.java
115
- ```java
116
- import android.os.Bundle;
117
- import android.view.View;
118
- import android.widget.EditText;
119
-
120
- import androidx.annotation.*;
121
- import androidx.fragment.app.Fragment;
122
- import androidx.lifecycle.ViewModelProvider;
123
-
124
- public class AFragment extends Fragment {
125
- AFragment() {
126
- super(R.layout.fragment_a);
127
- }
128
-
129
- @Override
130
- public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
131
- super.onViewCreated(view, savedInstanceState);
132
-
133
- SampleViewModel viewModel = new ViewModelProvider(requireActivity()).get(SampleViewModel.class);
134
-
135
- EditText editText = view.findViewById(R.id.editText);
136
- view.findViewById(R.id.setButton).setOnClickListener(v -> viewModel.setText(editText.getText().toString()));
137
- }
138
- }
139
- ```
140
- res/layout/fragment_a.xml
141
- ```xml
142
- <?xml version="1.0" encoding="utf-8"?>
143
- <LinearLayout
144
- xmlns:android="http://schemas.android.com/apk/res/android"
145
- xmlns:tools="http://schemas.android.com/tools"
146
- android:layout_width="match_parent"
147
- android:layout_height="match_parent"
148
- android:orientation="vertical"
149
- android:background="#ffffC0ff"
150
- tools:context=".AFragment">
151
-
152
- <TextView
153
- android:layout_width="match_parent"
154
- android:layout_height="wrap_content"
155
- android:text="A FRAGMENT"
156
- android:textSize="20dp" />
157
- <EditText
158
- android:id="@+id/editText"
159
- android:layout_width="match_parent"
160
- android:layout_height="wrap_content"
161
- android:textSize="15dp"/>
162
- <Button
163
- android:id="@+id/setButton"
164
- android:text="SET"
165
- android:layout_width="wrap_content"
166
- android:layout_height="wrap_content" />
167
-
168
- </LinearLayout>
169
- ```
170
- BFragment.java
171
- ```java
172
- import android.os.Bundle;
173
- import android.view.View;
174
- import android.widget.TextView;
175
-
176
- import androidx.annotation.*;
177
- import androidx.fragment.app.Fragment;
178
- import androidx.lifecycle.ViewModelProvider;
179
-
180
- public class BFragment extends Fragment {
181
- BFragment() {
182
- super(R.layout.fragment_b);
183
- }
184
-
185
- @Override
186
- public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
187
- super.onViewCreated(view, savedInstanceState);
188
-
189
- SampleViewModel viewModel = new ViewModelProvider(requireActivity()).get(SampleViewModel.class);
190
-
191
- TextView textView = view.findViewById(R.id.textView);
192
- viewModel.getText().observe(getViewLifecycleOwner(), text -> textView.setText(text));
193
- }
194
- }
195
- ```
196
- res/layout/fragment_b.xml
197
- ```xml
198
- <?xml version="1.0" encoding="utf-8"?>
199
- <LinearLayout
200
- xmlns:android="http://schemas.android.com/apk/res/android"
201
- xmlns:tools="http://schemas.android.com/tools"
202
- android:layout_width="match_parent"
203
- android:layout_height="match_parent"
204
- android:orientation="vertical"
205
- android:background="#ffffff80"
206
- tools:context=".BFragment">
207
-
208
- <TextView
209
- android:layout_width="match_parent"
210
- android:layout_height="wrap_content"
211
- android:text="B FRAGMENT"
212
- android:textSize="20dp"/>
213
- <TextView
214
- android:id="@+id/textView"
215
- android:layout_width="match_parent"
216
- android:layout_height="wrap_content"
217
- android:textSize="20dp"/>
218
-
219
- </LinearLayout>
220
- ```
221
-
222
- > MainActivity mainActivity = (MainActivity) getActivity();
223
- > mainActivity.onReturnValue(0,0,flag_count,0,0);
224
-
225
- これはフラグメントからアクティビティなら出来ますが、アクティビティからアクティビティへは出来ないのではないでしょうか。

1

コード追加

2022/03/26 07:12

投稿

jimbe
jimbe

スコア12659

test CHANGED
@@ -1,4 +1,223 @@
1
1
  表示中のフラグメントに対し別のフラグメントやアクティビティから値を渡すのであれば、 ViewModel を経由するのが妥当に思います。
2
+
3
+ MainActivity.java
4
+ ```java
5
+ import android.os.Bundle;
6
+ import android.widget.EditText;
7
+
8
+ import androidx.appcompat.app.AppCompatActivity;
9
+ import androidx.lifecycle.ViewModelProvider;
10
+
11
+ public class MainActivity extends AppCompatActivity {
12
+
13
+ @Override
14
+ protected void onCreate(Bundle savedInstanceState) {
15
+ super.onCreate(savedInstanceState);
16
+ setContentView(R.layout.activity_main);
17
+
18
+ SampleViewModel viewModel = new ViewModelProvider(this).get(SampleViewModel.class);
19
+
20
+ EditText editText = findViewById(R.id.editText);
21
+ findViewById(R.id.setButton).setOnClickListener(v -> viewModel.setText(editText.getText().toString()));
22
+
23
+ getSupportFragmentManager().beginTransaction()
24
+ .replace(R.id.fragment1, new AFragment())
25
+ .replace(R.id.fragment2, new BFragment())
26
+ .commit();
27
+ }
28
+ }
29
+ ```
30
+ res/layout/activity_main.xml
31
+ ```xml
32
+ <?xml version="1.0" encoding="utf-8"?>
33
+ <androidx.constraintlayout.widget.ConstraintLayout
34
+ xmlns:android="http://schemas.android.com/apk/res/android"
35
+ xmlns:app="http://schemas.android.com/apk/res-auto"
36
+ xmlns:tools="http://schemas.android.com/tools"
37
+ android:layout_width="match_parent"
38
+ android:layout_height="match_parent"
39
+ tools:context=".MainActivity">
40
+
41
+ <LinearLayout
42
+ android:id="@+id/activity"
43
+ android:layout_width="0dp"
44
+ android:layout_height="wrap_content"
45
+ android:orientation="vertical"
46
+ android:background="#ff80ffff"
47
+ app:layout_constraintLeft_toLeftOf="parent"
48
+ app:layout_constraintRight_toLeftOf="@id/arrow"
49
+ app:layout_constraintTop_toTopOf="parent">
50
+ <TextView
51
+ android:layout_width="match_parent"
52
+ android:layout_height="wrap_content"
53
+ android:text="ACTIVITY"
54
+ android:textSize="20dp" />
55
+ <EditText
56
+ android:id="@+id/editText"
57
+ android:layout_width="match_parent"
58
+ android:layout_height="wrap_content"
59
+ android:textSize="15dp"/>
60
+ <Button
61
+ android:id="@+id/setButton"
62
+ android:text="SET"
63
+ android:layout_width="wrap_content"
64
+ android:layout_height="wrap_content" />
65
+ </LinearLayout>
66
+
67
+ <LinearLayout
68
+ android:id="@+id/fragment1"
69
+ android:layout_width="0dp"
70
+ android:layout_height="wrap_content"
71
+ android:orientation="vertical"
72
+ app:layout_constraintLeft_toLeftOf="parent"
73
+ app:layout_constraintRight_toRightOf="@id/activity"
74
+ app:layout_constraintTop_toBottomOf="@id/activity" />
75
+
76
+ <TextView
77
+ android:id="@+id/arrow"
78
+ android:text="＞"
79
+ android:textSize="20dp"
80
+ android:layout_width="wrap_content"
81
+ android:layout_height="wrap_content"
82
+ app:layout_constraintBottom_toBottomOf="@id/fragment1"
83
+ app:layout_constraintLeft_toRightOf="@id/activity"
84
+ app:layout_constraintRight_toLeftOf="@id/fragment2"
85
+ app:layout_constraintTop_toTopOf="parent" />
86
+
87
+ <LinearLayout
88
+ android:id="@+id/fragment2"
89
+ android:layout_width="0dp"
90
+ android:layout_height="wrap_content"
91
+ android:orientation="vertical"
92
+ app:layout_constraintLeft_toRightOf="@id/arrow"
93
+ app:layout_constraintRight_toRightOf="parent"
94
+ app:layout_constraintTop_toTopOf="parent" />
95
+
96
+ </androidx.constraintlayout.widget.ConstraintLayout>
97
+ ```
98
+ SampleViewModel.java
99
+ ```java
100
+ import androidx.lifecycle.*;
101
+
102
+ public class SampleViewModel extends ViewModel {
103
+ private MutableLiveData<String> textLiveData = new MutableLiveData<>("init");
104
+
105
+ LiveData<String> getText() {
106
+ return textLiveData;
107
+ }
108
+
109
+ void setText(String text) {
110
+ textLiveData.setValue(text);
111
+ }
112
+ }
113
+ ```
114
+ AFragment.java
115
+ ```java
116
+ import android.os.Bundle;
117
+ import android.view.View;
118
+ import android.widget.EditText;
119
+
120
+ import androidx.annotation.*;
121
+ import androidx.fragment.app.Fragment;
122
+ import androidx.lifecycle.ViewModelProvider;
123
+
124
+ public class AFragment extends Fragment {
125
+ AFragment() {
126
+ super(R.layout.fragment_a);
127
+ }
128
+
129
+ @Override
130
+ public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
131
+ super.onViewCreated(view, savedInstanceState);
132
+
133
+ SampleViewModel viewModel = new ViewModelProvider(requireActivity()).get(SampleViewModel.class);
134
+
135
+ EditText editText = view.findViewById(R.id.editText);
136
+ view.findViewById(R.id.setButton).setOnClickListener(v -> viewModel.setText(editText.getText().toString()));
137
+ }
138
+ }
139
+ ```
140
+ res/layout/fragment_a.xml
141
+ ```xml
142
+ <?xml version="1.0" encoding="utf-8"?>
143
+ <LinearLayout
144
+ xmlns:android="http://schemas.android.com/apk/res/android"
145
+ xmlns:tools="http://schemas.android.com/tools"
146
+ android:layout_width="match_parent"
147
+ android:layout_height="match_parent"
148
+ android:orientation="vertical"
149
+ android:background="#ffffC0ff"
150
+ tools:context=".AFragment">
151
+
152
+ <TextView
153
+ android:layout_width="match_parent"
154
+ android:layout_height="wrap_content"
155
+ android:text="A FRAGMENT"
156
+ android:textSize="20dp" />
157
+ <EditText
158
+ android:id="@+id/editText"
159
+ android:layout_width="match_parent"
160
+ android:layout_height="wrap_content"
161
+ android:textSize="15dp"/>
162
+ <Button
163
+ android:id="@+id/setButton"
164
+ android:text="SET"
165
+ android:layout_width="wrap_content"
166
+ android:layout_height="wrap_content" />
167
+
168
+ </LinearLayout>
169
+ ```
170
+ BFragment.java
171
+ ```java
172
+ import android.os.Bundle;
173
+ import android.view.View;
174
+ import android.widget.TextView;
175
+
176
+ import androidx.annotation.*;
177
+ import androidx.fragment.app.Fragment;
178
+ import androidx.lifecycle.ViewModelProvider;
179
+
180
+ public class BFragment extends Fragment {
181
+ BFragment() {
182
+ super(R.layout.fragment_b);
183
+ }
184
+
185
+ @Override
186
+ public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
187
+ super.onViewCreated(view, savedInstanceState);
188
+
189
+ SampleViewModel viewModel = new ViewModelProvider(requireActivity()).get(SampleViewModel.class);
190
+
191
+ TextView textView = view.findViewById(R.id.textView);
192
+ viewModel.getText().observe(getViewLifecycleOwner(), text -> textView.setText(text));
193
+ }
194
+ }
195
+ ```
196
+ res/layout/fragment_b.xml
197
+ ```xml
198
+ <?xml version="1.0" encoding="utf-8"?>
199
+ <LinearLayout
200
+ xmlns:android="http://schemas.android.com/apk/res/android"
201
+ xmlns:tools="http://schemas.android.com/tools"
202
+ android:layout_width="match_parent"
203
+ android:layout_height="match_parent"
204
+ android:orientation="vertical"
205
+ android:background="#ffffff80"
206
+ tools:context=".BFragment">
207
+
208
+ <TextView
209
+ android:layout_width="match_parent"
210
+ android:layout_height="wrap_content"
211
+ android:text="B FRAGMENT"
212
+ android:textSize="20dp"/>
213
+ <TextView
214
+ android:id="@+id/textView"
215
+ android:layout_width="match_parent"
216
+ android:layout_height="wrap_content"
217
+ android:textSize="20dp"/>
218
+
219
+ </LinearLayout>
220
+ ```
2
221
 
3
222
  > MainActivity mainActivity = (MainActivity) getActivity();
4
223
  > mainActivity.onReturnValue(0,0,flag_count,0,0);