この場合、アクティビティコンテキストを取得する方法は？

Question

適切なインテントを作成する際に問題が発生しています。インテントは、コンテキストの下に赤い線を表示します。ここで私のコードは、私がこの問題を取り除くのを助けることができます。

これは、これはこれはMc1_Activity.javaによって指定タブ活性の断片活動であるPlaceholderFragment.java

public class PlaceholderFragment extends Fragment { 
/** 
* The fragment argument representing the section number for this 
* fragment. 
*/ 
private static final String ARG_SECTION_NUMBER = "section_number"; 

public PlaceholderFragment() { 
} 

/** 
* Returns a new instance of this fragment for the given section 
* number. 
*/ 
public static PlaceholderFragment newInstance(int sectionNumber) { 
    PlaceholderFragment fragment = new PlaceholderFragment(); 
    Bundle args = new Bundle(); 
    args.putInt(ARG_SECTION_NUMBER, sectionNumber); 
    fragment.setArguments(args); 
    return fragment; 
} 
} 

ある MainCategory.java（タブ活性）

public class MainCategory extends AppCompatActivity { 

/** 
* The {@link android.support.v4.view.PagerAdapter} that will provide 
* fragments for each of the sections. We use a 
* {@link FragmentPagerAdapter} derivative, which will keep every 
* loaded fragment in memory. If this becomes too memory intensive, it 
* may be best to switch to a 
* {@link android.support.v4.app.FragmentStatePagerAdapter}. 
*/ 
private SectionsPagerAdapter mSectionsPagerAdapter; 

/** 
* The {@link ViewPager} that will host the section contents. 
*/ 
private ViewPager mViewPager; 

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

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 
    // Create the adapter that will return a fragment for each of the three 
    // primary sections of the activity. 
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager()); 

    // Set up the ViewPager with the sections adapter. 
    mViewPager = (ViewPager) findViewById(R.id.container); 
    mViewPager.setAdapter(mSectionsPagerAdapter); 


    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
    fab.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
        .setAction("Action", null).show(); 
     } 
    }); 

} 


@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.menu_main_category, menu); 
    return true; 
} 

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    // Handle action bar item clicks here. The action bar will 
    // automatically handle clicks on the Home/Up button, so long 
    // as you specify a parent activity in AndroidManifest.xml. 
    int id = item.getItemId(); 

    //noinspection SimplifiableIfStatement 
    if (id == R.id.action_settings) { 
     return true; 
    } 

    return super.onOptionsItemSelected(item); 
} 

/** 
* A placeholder fragment containing a simple view. 
*/ 


/** 
* A {@link FragmentPagerAdapter} that returns a fragment corresponding to 
* one of the sections/tabs/pages. 
*/ 
public class SectionsPagerAdapter extends FragmentPagerAdapter { 

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

    @Override 
    public Fragment getItem(int position) { 
     // getItem is called to instantiate the fragment for the given page. 
     // Return a PlaceholderFragment (defined as a static inner class below). 
     switch(position){ 
      case 0: return Mc1_Activity.newInstance(); 
      case 1 : return Mc2_Activity.newInstance() ; 
      // default: return MyFragment.newInstance(); 

     } 
     return null; 

    } 

    @Override 
    public int getCount() { 
     // Show 3 total pages. 
     return 2; 
    } 

    @Override 
    public CharSequence getPageTitle(int position) { 
     switch (position) { 
      case 0: 
       return "SECTION 1"; 
      case 1: 
       return "SECTION 2"; 
      case 2: 
       return "SECTION 3"; 
     } 
     return null; 
    } 
} 
} 

あります

public class Mc1_Activity extends Fragment { 

public static Mc1_Activity newInstance() { 
    Mc1_Activity fragment = new Mc1_Activity(); 
    return fragment; 
} 

public Mc1_Activity() { 
} 

ImageView iv; 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    View rootView = inflater.inflate(R.layout.mc1_fragment, container, false); 
    iv = (ImageView) rootView.findViewById(R.id.iv_mc1); 
    iv.setBackgroundResource(R.drawable.mc1); 

    iv.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Intent go = new Intent(this,next_activity.class); 
      startActivity(go); 
     } 
    }); 
    return rootView; 
} 
} 

これはこれは私が文脈のこのステップで問題を取得していActivity_Main_Category.xml

<?xml version="1.0" encoding="utf-8"?> 

<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:background="?attr/colorPrimary" 
     app:layout_scrollFlags="scroll|enterAlways" 
     app:popupTheme="@style/AppTheme.PopupOverlay"> 

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

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

<android.support.v4.view.ViewPager 
    android:id="@+id/container" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    app:layout_behavior="@string/appbar_scrolling_view_behavior" /> 

<android.support.design.widget.FloatingActionButton 
    android:id="@+id/fab" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_gravity="end|bottom" 
    android:layout_margin="@dimen/fab_margin" 
    android:src="@android:drawable/ic_dialog_email" /> 

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

あるmc1_fragment.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
tools:context="com.example.user.evacookingrecipes.MainCategory"> 

<ImageView 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:id="@+id/iv_mc1" 
    android:layout_alignParentTop="true" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentStart="true" /> 
</RelativeLayout> 

です。

iv.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Intent go = new Intent(this,SoupDesertsCooking.class); 
      startActivity(go); 
     } 
    }); 

Answer 1

iv.setOnClickListener(new View.OnClickListener() { 
    @Override 
    public void onClick(View view) { 
     Intent go = new Intent(getActivity(),next_activity.class); 
     startActivity(go); 
    } 
}); 

Answer 2

このような使用をthisは、あなたのフラグメントでonClickコンテキスト渡しているので：

iv.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Intent go = new Intent(getActivity(),SoupDesertsCooking.class); 
      startActivity(go); 
     } 
    }); 

Answer 3

getActivity()

iv.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      Intent go = new Intent(getActivity(), SoupDesertsCooking.class); 
      startActivity(go); 
     } 
    }); 

Answer 4

二つのオプションからいずれかを使用します。

を3210

Intent go = new Intent(getActivity(), SoupDesertsCooking.class); 
startActivity(go); 

または

Intent go = new Intent(getContext(), SoupDesertsCooking.class); 
startActivity(go);