[Android] Tab上でFragmentからFragmentの実装メモ

TabLayout上でのFragmentとFragment間の簡単な画面遷移の実装メモです。
ToolbarにMenuItemを表示しているコードも含まれています。
勉強中なので、おかしい部分があるかもしれないです、、

#作ったもの
3つのタブがあり、TAB01に画面遷移するボタンがあります。
<img width="438" alt="スクリーンショット 2019-02-07 21.36.26.png" src="https://qiita-image-store.s3.amazonaws.com/0/281645/b41923b0-ec67-5dff-4199-c8194e325cbb.png">
＊画面遷移後
Backボタンを押すとTAB01トップに戻ります。
<img width="437" alt="スクリーンショット 2019-02-07 21.36.49.png" src="https://qiita-image-store.s3.amazonaws.com/0/281645/3f537c44-6082-93d6-c7a0-bc43feedf750.png">

#MainActivity
```java:MainActivity.java
public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        OriginalFragmentPagerAdapter adapter = new 
        OriginalFragmentPagerAdapter(getSupportFragmentManager());
        ViewPager viewPager = findViewById(R.id.viewPager);
        viewPager.setOffscreenPageLimit(3);
        viewPager.setAdapter(adapter);

        TabLayout tabLayout = findViewById(R.id.tabLayout);
        tabLayout.setupWithViewPager(viewPager);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

```

#Tab01Fragment
```java:Tab01Fragment.java
public class Tab01Fragment extends Fragment {
   
    public Tab01Fragment() {
        // Required empty public constructor
    }


    private int cnt = 0;

    public static Tab01Fragment newInstance(int count){
        //Fragment インスタンス化
        Tab01Fragment tab01Fragment = new Tab01Fragment();

        //Bundleにパラメータを設定
        Bundle args = new Bundle();
        args.putInt("Counter", count);
        tab01Fragment.setArguments(args);

        return tab01Fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_tab01, container, false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        Bundle args = getArguments();

        if(args != null){
            int count = args.getInt("Counter");
            cnt = count + 1;
        }

        Button appButton = view.findViewById(R.id.Button);
        appButton.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){

                FragmentManager fragmentManager = getFragmentManager();

                if(fragmentManager != null){
                    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

                    //BackStackを設定
                    fragmentTransaction.addToBackStack(null);

                    fragmentTransaction.replace(R.id.container, Tab01NextFragment.newInstance(cnt));
                    fragmentTransaction.commit();
                }
            }
        });
    }
}
```

#Tab01NextFragment
```java:Tab01NextFragment.java
public class Tab01NextFragment extends Fragment {

        public Tab01NextFragment() {
            // Required empty public constructor
        }

    private int cnt = 0;

    public static Tab01NextFragment newInstance(int count){
        //Fragment インスタンス化
        Tab01NextFragment tab01NextFragment = new Tab01NextFragment();

        //Bundleにパラメータを設定
        Bundle args = new Bundle();
        args.putInt("Counter", count);
        tab01NextFragment.setArguments(args);

        return tab01NextFragment;
    }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            // Inflate the layout for this fragment
            return inflater.inflate(R.layout.fragment_tab01_next, container, false);
        }


        @Override
        public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);

            Bundle args = getArguments();

        if(args != null){
            int count = args.getInt("Counter");
            cnt = count + 1;
        }

            Button appButton = view.findViewById(R.id.backButton);
            appButton.setOnClickListener(new View.OnClickListener(){
                @Override
                public void onClick(View view){

                    FragmentManager fragmentManager = getFragmentManager();

                    if(fragmentManager != null){
                        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

                        //BackStackを設定
                        fragmentTransaction.addToBackStack(null);

                        fragmentTransaction.replace(R.id.container, Tab01Fragment.newInstance(cnt));
                        fragmentTransaction.commit();
                    }
                }
            });
        }
    }
```

#OriginalFragmentPagerAdapter
TabLayoutとviewPagerをくっつけるAdapterです。

```java:OriginalFragmentPagerAdapter.java
public class OriginalFragmentPagerAdapter extends FragmentPagerAdapter {

    private CharSequence[] tabTitles = {"Tab01", "Tab02", "Tab03"};

    public OriginalFragmentPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return tabTitles[position];
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
            case 0:
                return new Tab01Fragment();
            case 1:
                return new TabSystemFragment();
            case 2:
                return new TabAbnormalFragment();
            default:
                return null;
        }
    }

    @Override
    public int getCount() {
        return tabTitles.length;
    }
}
```
#Layout / activity_main.xml

```xml:activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".MainActivity">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/appbar_padding_top"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:layout_weight="1"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways"
            app:popupTheme="@style/AppTheme.PopupOverlay"
            app:title="@string/app_name">

        </android.support.v7.widget.Toolbar>

    </android.support.design.widget.AppBarLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <android.support.design.widget.TabLayout
            android:id="@+id/tabLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <android.support.design.widget.TabItem
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Left" />

            <android.support.design.widget.TabItem
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Center" />

            <android.support.design.widget.TabItem
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Right" />
        </android.support.design.widget.TabLayout>

        <android.support.v4.view.ViewPager
            android:id="@+id/viewPager"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

        </android.support.v4.view.ViewPager>

    </LinearLayout>

</android.support.design.widget.CoordinatorLayout>
```

#Layout / fragment_tab01.xml

```xml:fragment_tab01.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Tab01Fragment">

    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <Button
            android:id="@+id/Button"
            android:layout_width="211dp"
            android:layout_height="wrap_content"
            android:layout_marginStart="8dp"
            android:layout_marginTop="8dp"
            android:layout_marginEnd="8dp"
            android:layout_marginBottom="8dp"
            android:text="ToFragment"
            android:textAllCaps="false"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.503"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.393" />
    </android.support.constraint.ConstraintLayout>

</FrameLayout>
```
#Layout / fragment_tab01_next.xml

```xml:fragment_tab01_next.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ff97"
    android:clickable="true"
    tools:context=".Tab01NextFragment">

    <Button
        android:id="@+id/backButton"
        android:layout_width="157dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="Back Tab01"
        android:textAllCaps="false"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.502"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        app:layout_constraintVertical_bias="0.157" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="132dp"
        android:layout_marginEnd="8dp"
        android:text="画面遷移完了"
        android:textSize="24sp"
        android:textStyle="bold"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
```
#menu / menu_main.xml
Toolbarのメニューボタン。

```xml:menu_main.xml
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context="com.example.hayato.sample_iseandroid.MainActivity">
    <item
        android:id="@+id/action_settings"
        android:orderInCategory="100"
        android:title="@string/action_settings"
        app:showAsAction="never" />
</menu>
```
おわり！