プロジェクトをグラデーションに移行した後のNULLポインタの例外

Question

プロジェクトをgradleに移行した後、次のエラーが発生します。なぜこれが起こっているのか分からず、移行する前にこれが機能していました。私はグランドビルドパッケージからビルドされたまったく新しいプロジェクトにファイルをコピーしようとしましたが、今はこれらの問題を抱えています。

Process: com.hospital.headling.hospital, PID: 5243 
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.hospital.headling.hospital/com.hospital.headling.hospital.ListViewActivity}: java.lang.NullPointerException: Attempinvoke virtual method 'void com.hospital.headling.hospital.util.ExpandableHeightGridView.setAdapter(android.widget.ListAdapter)' on a null object reference 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726) 
at android.app.ActivityThread.-wrap12(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.hospital.headling.hospital.util.ExpandableHeightGridView.setAdapter(android.widget.ListAdapter)' on a null object reference 
at com.hospital.headling.hospital.ListViewActivity.setAdapters(ListViewActivity.java:127) 
at com.hospital.headling.hospital.ListViewActivity.onCreate(ListViewActivity.java:61) 
at android.app.Activity.performCreate(Activity.java:6679) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)  
at android.app.ActivityThread.-wrap12(ActivityThread.java)  
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)  
atandroid.os.Handler.dispatchMessage(Handler.java:102)  
at android.os.Looper.loop(Looper.java:154)  
at android.app.ActivityThread.main(ActivityThread.java:6119)  
at java.lang.reflect.Method.invoke(Native Method)  
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)  
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)  

ListViewActivity.java

package com.hospital.headling.hospital; 

    import android.annotation.SuppressLint; 
    import android.app.Activity; 
    import android.content.Intent; 
    import android.os.Bundle; 
    import android.view.View; 
    import android.widget.AdapterView; 
    import android.widget.ArrayAdapter; 
    import android.widget.ListView; 

    import com.hospital.headling.hospital.adapter.CustomAdapter; 
    import com.hospital.headling.hospital.util.ExpandableHeightGridView; 

    import org.apache.commons.lang3.ArrayUtils; 

    import java.util.ArrayList; 

    public class ListViewActivity extends Activity { 

     private ExpandableHeightGridView gridView; 
     private ListView listView; 


     //drawables array for gridview 
     private static final int[] osImage = { R.drawable.cardiac, R.drawable.ortho, 
       R.drawable.neuro, R.drawable.cancer, R.drawable.doctors, R.drawable.services, 
       R.drawable.visit, R.drawable.careers, R.drawable.bills, R.drawable.email, R.drawable.about }; 

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

      ArrayList<String> menu_links = new ArrayList<>(); 
      menu_links.add("Cardiac"); 
      menu_links.add("Orthopedic"); 
      menu_links.add("Neurosciences"); 
      menu_links.add("Cancer"); 
      menu_links.add("Find A Doctor"); 
      menu_links.add("Medical Services"); 
      menu_links.add("Patients and Visitors"); 
      menu_links.add("Careers"); 
      menu_links.add("Pay Your Bill"); 
    // Find a reference to the {@link ListView} in the layout 
      ListView companiesListView = (ListView) findViewById(R.id.list); 

    // Create a new {@link ArrayAdapter} of the menu_links 
      ArrayAdapter<String> adapter = new ArrayAdapter<String>(
        this, android.R.layout.simple_list_item_1, menu_links); 


    // Set the adapter on the {@link ListView} 
    // so the list can be populated in the user interface 
      companiesListView.setAdapter(adapter); 


      ///end of stuff 


      setAdapters(); 

      //start 
      companiesListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
       public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
        switch (position) { 
       /* case 0: Intent Cardiac = new Intent(this, Cardiac.class); 
         startActivity(Cardiac); 
         break; 
        case 1: Intent Orthopedic = new Intent(this, Orthopedic.class); 
         startActivity(newActivity); 
         break; 
        case 2: Intent Neurosciences = new Intent(this, Neurosciences.class); 
         startActivity(newActivity); 
         break; 
        case 3: Intent Cancer = new Intent(this, Cancer.class); 
         startActivity(FindADoctor); 
         break; 
        case 4: Intent newActivity = new Intent(this, reservetickets.class); 
         startActivity(newActivity); 
         break; 
        case 4: Intent newActivity = new Intent(this, reservetickets.class); 
         startActivity(newActivity); 
         break; 
        case 4: Intent newActivity = new Intent(this, reservetickets.class); 
         startActivity(newActivity); 
         break; 
        case 4: Intent newActivity = new Intent(this, reservetickets.class); 
         startActivity(newActivity); 
         break; */ 
         case 9: 
          Intent ContactForm = new Intent(ListViewActivity.this, com.hospital.headling.hospital.ContactForm.class); 
          startActivity(ContactForm); 
          break; 
        } 
       } 
      }); 
      //finish 

     } 

     /** 
     * set footer for listview (it's a gridview) 
     */ 
     @SuppressLint("InflateParams") 
     private void addGridViewAsListViewFooter() { 
      View footer = (View) getLayoutInflater().inflate(R.layout.layout_gridview, null); 
      listView.addFooterView(footer); 

      gridView = (ExpandableHeightGridView) footer.findViewById(R.id.gridview); 

      // set expand to show all gridview rows 
      gridView.setExpanded(true); 
     } 


     /** 
     * set adapters for list view and gridview 
     */ 
     private void setAdapters() { 
      // convert int array to Integer array by apache common lang library 
      Integer[] osImageList = ArrayUtils.toObject(osImage); 

      // set gridview adapter 
      CustomAdapter gridViewAdapter = new CustomAdapter(this, R.layout.item_grid, R.id.image, osImageList); 

      gridView.setAdapter(gridViewAdapter); 

     } 
    } 

ExampleHeightGridView.java

package com.hospital.headling.hospital.util; 

import android.content.Context; 
import android.util.AttributeSet; 
import android.view.ViewGroup; 
import android.widget.GridView; 

public class ExpandableHeightGridView extends GridView { 

    boolean expanded = false; 

    public ExpandableHeightGridView(Context context) { 
     super(context); 
    } 

    public ExpandableHeightGridView(Context context, AttributeSet attrs) { 
     super(context, attrs); 
    } 

    public ExpandableHeightGridView(Context context, AttributeSet attrs, int defStyle) { 
     super(context, attrs, defStyle); 
    } 

    public boolean isExpanded() { 
     return expanded; 
    } 

    @Override 
    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 
     if (isExpanded()) { 
      // Calculate entire height by providing a very large height hint. 
      // MEASURED_SIZE_MASK represents the largest height possible. 
      int expandSpec = MeasureSpec.makeMeasureSpec(MEASURED_SIZE_MASK, MeasureSpec.AT_MOST); 
      super.onMeasure(widthMeasureSpec, expandSpec); 

      ViewGroup.LayoutParams params = getLayoutParams(); 
      params.height = getMeasuredHeight(); 
     } else { 
      super.onMeasure(widthMeasureSpec, heightMeasureSpec); 
     } 
    } 

    public void setExpanded(boolean expanded) { 
     this.expanded = expanded; 
    } 
} 

layout_gridview.xml

<LinearLayout 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" 
    android:orientation="vertical" > 



    <com.healinghospital.healinghospital.util.ExpandableHeightGridView 
     android:id="@+id/gridview" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:gravity="center" 
     android:horizontalSpacing="10dp" 
     android:verticalSpacing="10dp" 
     android:numColumns="6" 
     android:stretchMode="columnWidth"/> 

    <!--<TextView 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_marginTop="10dp" 
     android:background="#000099" 
     android:text="@string/corporation" 
     android:textColor="@android:color/white" /> --> 

    <TextView 
     android:id="@+id/list" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_marginTop="10dp" 
     android:background="#000099" 
     android:textColor="@android:color/white" /> 


</LinearLayout> 

activity_mail.xml

<LinearLayout 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" 
    android:orientation="vertical"> 

    <ListView 
     android:id="@+id/list" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content"/> 

</LinearLayout> 

CustomAdapter.java

package com.hospital.headling.hospital.adapter; 
import android.app.Activity; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.ArrayAdapter; 
import android.widget.ImageView; 

import com.hospital.headling.hospital.R; 

public class CustomAdapter extends ArrayAdapter<Integer> { 

    private Activity activity; 

    public CustomAdapter(Activity activity, int resource, int textViewResourceId, Integer[] osimage) { 
     super(activity, resource, textViewResourceId, osimage); 
     this.activity = activity; 
    } 



    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 

     ViewHolder holder = null; 

     // inflate layout from xml 
     LayoutInflater inflater = (LayoutInflater) activity 
      .getSystemService(Activity.LAYOUT_INFLATER_SERVICE); 

     // If holder not exist then locate all view from UI file. 
     if (convertView == null) { 
      // inflate UI from XML file 
      convertView = inflater.inflate(R.layout.item_grid, parent, false); 
      // get all UI view 
      holder = new ViewHolder(convertView); 
      // set tag for holder 
      convertView.setTag(holder); 
     } else { 
      // if holder created, get tag from view 
      holder = (ViewHolder) convertView.getTag(); 
     } 

     holder.image.setImageResource(getItem(position)); 

     return convertView; 
    } 

    private class ViewHolder { 
     private ImageView image; 

     public ViewHolder(View v) { 
      image = (ImageView)v.findViewById(R.id.image); 
     } 
    } 
} 

Answer 1

あなたのExpandableHeightGridViewを初期化する方法addGridViewAsListViewFooter()を呼び出すことはありません。だから、この行の

gridView = (ExpandableHeightGridView) footer.findViewById(R.id.gridview); 

：ここ

gridView.setAdapter(gridViewAdapter); 

gridViewが初期化されることはありませんので、それはNullPointerException

がsetAdapter()