Android Java - NullpointerException, view1.setAlpha'da mı?

Question

İlk: UZUN kod için özür dilerim. Bir göz atabilirseniz çok mutlu olurdum ... En alttaki detaylar.

package com.as.zippedmessagingservice; 

import android.animation.Animator; 
import android.animation.AnimatorListenerAdapter; 
import android.content.Context; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.util.Base64; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.AdapterView; 
import android.widget.ArrayAdapter; 
import android.widget.ImageView; 
import android.widget.ListView; 
import android.widget.TextView; 

import java.security.Key; 
import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.LinkedHashMap; 
import java.util.List; 
import java.util.Map; 

import javax.crypto.Cipher; 

import static com.as.zippedmessagingservice.MainActivity.getHashElement; 
import static com.as.zippedmessagingservice.MainActivity.getHashKeys; 









public class MainActivity extends AppCompatActivity { 
    private int ShortAnimationDuration; 
    private View HomeView; 
    private View ChatView; 


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

     //! Get UI Items 
     TextView frame_title = (TextView) findViewById(R.id.frame_title); 
     ListView contacts = (ListView) findViewById(R.id.listview); 
     View HomeView = (View) findViewById(R.id.HomeView);      //Get Home View from activity_main.xml 
     View ChatView = (View) findViewById(R.id.ChatView);      //Get Chat View from activity_main.xml 
     ChatView.setVisibility(View.GONE);           //Hide the Chat screen 
     frame_title.setText(R.string.recent_convs);         // Set Frame Title 
     //! Create Variables and other Stuff 
     ShortAnimationDuration = getResources().getInteger(android.R.integer.config_shortAnimTime); 
     LinkedHashMap<String,String> contact_tree = new LinkedHashMap<String,String>() {{ 
                   put("Android","Hello Guys ;-)"); 
                   put("iPhone","What's up Folks?"); 
                   put("Linux","Hi ;D"); }}; 


     final MySimpleArrayAdapter adapter = new MySimpleArrayAdapter(this, contact_tree); 
     contacts.setAdapter(adapter); 

     contacts.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
      @Override 
      public void onItemClick(AdapterView<?> parent, final View view, 
            int position, long id) { 
       final String item = (String) parent.getItemAtPosition(position); 
       goToChat(item); 

       } 
     }); 
    } 
    public static String[] getHashElement(HashMap<String,String> hash, Integer item_index) { 
     for (Map.Entry entry : hash.entrySet()) { 
      if (item_index-- == 0) { 
       return new String[] {(String) entry.getKey(),(String) entry.getValue()}; } 
     } 
     return new String[] {"getHashElement(): Requested Item Index not in Range","Error! See getHashElement()[0] for more details..."}; 
    } 
    public static List getHashKeys(HashMap<String,String> hash) { List<String> indexes = new ArrayList<String>(hash.keySet()); return indexes;} 
    private void goToChat(String item) { 
     crossfade(ChatView, HomeView); 
     //getActionBar().setTitle(item); 
    } 
    private void crossfade(final View view1, final View view2) { 
     // Set the content view to 0% opacity but visible, so that it is visible 
     // (but fully transparent) during the animation. 
     view1.setAlpha(0f); 
     view1.setVisibility(View.VISIBLE); 

     // Animate the content view to 100% opacity, and clear any animation 
     // listener set on the view. 
     view1.animate() 
       .alpha(1f) 
       .setDuration(ShortAnimationDuration) 
       .setListener(null); 

     // Animate the loading view to 0% opacity. After the animation ends, 
     // set its visibility to GONE as an optimization step (it won't 
     // participate in layout passes, etc.) 
     view2.animate() 
       .alpha(0f) 
       .setDuration(ShortAnimationDuration) 
       .setListener(new AnimatorListenerAdapter() { 
        @Override 
        public void onAnimationEnd(Animator animation) { 
         view2.setVisibility(View.GONE); 
        } 
       }); 
    } 
} 


class MySimpleArrayAdapter extends ArrayAdapter<String> { 
    private final Context context; 
    private final HashMap<String, String> values; 
    public MySimpleArrayAdapter(Context context, LinkedHashMap<String,String> values) { 
     super(context, -1, getHashKeys(values)); 
     this.context = context; 
     this.values = values; 
    } 

    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
     LayoutInflater inflater = (LayoutInflater) context 
       .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     View rowView = inflater.inflate(R.layout.single_contact_layout, parent, false); 
     TextView textView = (TextView) rowView.findViewById(R.id.firstLine); 
     TextView lastMessage = (TextView) rowView.findViewById(R.id.secondLine); 
     ImageView imageView = (ImageView) rowView.findViewById(R.id.icon); 
     textView.setText(getHashElement(values,position)[0]); 
     lastMessage.setText(getHashElement(values,position)[1]); 
     // change the icon for Windows and iPhone 
     String s = getHashElement(values,position)[0]; 
     if (s.startsWith("iPhone")) { 
      imageView.setImageResource(R.mipmap.ic_launcher); 
     } else { 
      imageView.setImageResource(R.drawable.contact); 
     } 

     return rowView; 
    } 
} 

Benim Activity_Main.xml

<?xml version="1.0" encoding="utf-8"?> 
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
     xmlns:tools="http://schemas.android.com/tools" 
     android:orientation="vertical" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:paddingBottom="@dimen/activity_vertical_margin" 
     android:paddingLeft="@dimen/activity_horizontal_margin" 
     android:paddingRight="@dimen/activity_horizontal_margin" 
     android:paddingTop="@dimen/activity_vertical_margin" 
     tools:context="com.as.zippedmessagingservice.MainActivity" 
     android:id="@+id/HomeView"> 

     <TextView 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:text="{frame_title}" 
      android:textSize="20dp" 
      android:id="@+id/frame_title" /> 
     <ListView xmlns:android="http://schemas.android.com/apk/res/android" 
      android:id="@+id/listview" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" /> 
    </LinearLayout> 


    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
     xmlns:tools="http://schemas.android.com/tools" 
     android:orientation="vertical" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:paddingBottom="@dimen/activity_vertical_margin" 
     android:paddingLeft="@dimen/activity_horizontal_margin" 
     android:paddingRight="@dimen/activity_horizontal_margin" 
     android:paddingTop="@dimen/activity_vertical_margin" 
     tools:context="com.as.zippedmessagingservice.MainActivity" 
     android:id="@+id/ChatView"> 
     <TextView 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:text="@string/chat_here_later" 
      android:textSize="40dp" 
      android:id="@+id/chat_here_later" /> 
    </LinearLayout> 
</FrameLayout> 

Bu benim kodudur. Line 78'de (Android Studio'da view1.setalpha'da public void crossfade) bana bir nullpointerexception veriyor ve nedenini anlayamıyorum. Lütfen bana yardım edin! Ben senin onCreate yönteme ... vb

Answer 1

Git gradle dosyaları değiştirmek ve bu bir tanımlarken

HomeView = (View) findViewById(R.id.HomeView); ChatView = (View) findViewById(R.id.ChatView);

Çünkü bu

View HomeView = (View) findViewById(R.id.HomeView); View ChatView = (View) findViewById(R.id.ChatView);

yerine vermedi yönteminizde yeni değişken olan global değişken boş kalır.