Android Studio: FATAL EXCEPTION

Question

Я пытаюсь создать приложение. При тестировании, когда я пытаюсь нажать кнопку, приложение на телефоне говорит: «К сожалению, [имя приложения] остановлено».

На LogCat, появляется сообщение:

E/AndroidRuntime: FATAL EXCEPTION: main 
Process: com.example.inspiron.firstapplication, PID: 6746 
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.inspiron.firstapplication/com.example.inspiron.firstapplication.Text}: java.lang.NullPointerException 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2321) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2507) 
    at android.app.ActivityThread.access$900(ActivityThread.java:172) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:146) 
    at android.app.ActivityThread.main(ActivityThread.java:5692) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:515) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
    at dalvik.system.NativeStart.main(Native Method) 
    Caused by: java.lang.NullPointerException 
    at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:68) 
    at android.support.v7.app.AppCompatDelegateImplV7.<init>(AppCompatDelegateImplV7.java:146) 
    at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:28) 
    at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:41) 
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:190) 
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:172) 
    at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:512) 
    at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:184) 
    at com.example.inspiron.firstapplication.Text.<init>(Text.java:17) 
    at java.lang.Class.newInstanceImpl(Native Method) 
    at java.lang.Class.newInstance(Class.java:1208) 
    at android.app.Instrumentation.newActivity(Instrumentation.java:1067) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2312) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2507)  
    at android.app.ActivityThread.access$900(ActivityThread.java:172)  
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308)  
    at android.os.Handler.dispatchMessage(Handler.java:102)  
    at android.os.Looper.loop(Looper.java:146)  
    at android.app.ActivityThread.main(ActivityThread.java:5692)  
    at java.lang.reflect.Method.invokeNative(Native Method)  
    at java.lang.reflect.Method.invoke(Method.java:515)  
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)  
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)  
    at dalvik.system.NativeStart.main(Native Method)  

Мой XML выглядит следующим образом:

<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="English:" 
    android:id="@+id/LanguageTranslatedFrom" 
    android:layout_alignParentTop="true" 
    android:layout_alignParentStart="true" 
    android:textSize="20dp" /> 

<EditText 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/TextBar" 
    android:layout_below="@+id/LanguageTranslatedFrom" 
    android:layout_toEndOf="@+id/LanguageTranslatedFrom" 
    android:hint="PUT IN what you want to translate..." /> 

<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="Spanish:" 
    android:id="@+id/LanguageTranslatedTo" 
    android:layout_centerVertical="true" 
    android:layout_alignParentStart="true" 
    android:textSize="20dp" /> 

<Button 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="OK" 
    android:id="@+id/ConfirmationButton" 
    android:layout_below="@+id/TextBar" 
    android:layout_alignParentEnd="true" 
    android:background="#61ff00" /> 

<ImageButton 
    android:layout_width="50dp" 
    android:layout_height="100dp" 
    android:id="@+id/TextIcon" 
    android:src="@drawable/keyboard" 
    android:layout_centerVertical="true" 
    android:layout_toEndOf="@+id/LanguageTranslatedTo" 
    android:layout_alignParentEnd="true" /> 

<ImageButton 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/ViaVoiceButton" 
    android:layout_below="@+id/LanguageTranslatedTo" 
    android:layout_alignParentStart="true" 
    android:src="@drawable/microphone" 
    android:layout_toStartOf="@+id/Result" /> 

<TextView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:textAppearance="?android:attr/textAppearanceMedium" 
    android:text="What the output is..." 
    android:id="@+id/Result" 
    android:layout_below="@+id/TextIcon" 
    android:layout_toEndOf="@+id/LanguageTranslatedTo" 
    android:textSize="18dp" /> 

<Button 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="Retry" 
    android:id="@+id/Retryit" 
    android:layout_below="@+id/ConfirmationButton" 
    android:layout_alignParentEnd="true" 
    android:background="#61ff00" /> 

<Button 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="BACK" 
    android:id="@+id/button" 
    android:layout_alignParentBottom="true" 
    android:layout_toStartOf="@+id/Result" 
    android:background="#ff0000" /> 

<Spinner 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/LanguagePicker" 
    android:layout_above="@+id/TextBar" 
    android:layout_toEndOf="@+id/Result" /> 

<FrameLayout 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:layout_above="@+id/LanguageTranslatedTo" 
    android:layout_centerHorizontal="true"> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="New Text" 
     android:id="@+id/textView2" 
     android:layout_gravity="left|top" /> 
</FrameLayout> 

Наконец, моя ява выглядит следующим образом:

import android.app.AlertDialog; 
import android.content.Context; 
import android.content.DialogInterface; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 

import android.view.LayoutInflater; 
import android.view.View; 
import android.widget.ArrayAdapter; 
import android.widget.Button; 
import android.widget.Spinner; 

public class Text extends AppCompatActivity { 
    final Context context = this; 
    Button button = (Button) findViewById(R.id.ConfirmationButton); 


protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.text_wall); 
    Spinner spinner = (Spinner) findViewById(R.id.LanguagePicker); 



    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, 
      R.array.language, android.R.layout.simple_spinner_item); 

    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 

    spinner.setAdapter(adapter); 
    button.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      LayoutInflater li = LayoutInflater.from(context); 
      View promptsView = li.inflate(R.layout.alertdialog, null); 

      AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
        context); 


      alertDialogBuilder.setView(promptsView); 
      alertDialogBuilder 
        .setCancelable(false) 
        .setPositiveButton("OK", 
          new DialogInterface.OnClickListener() { 
           public void onClick(DialogInterface dialog,int id) { 

            Spinner spinner = (Spinner) findViewById(R.id.LanguagePicker); 
            String text = spinner.getSelectedItem().toString(); 
           } 
          }) 
        .setNegativeButton("Cancel", 
          new DialogInterface.OnClickListener() { 
           public void onClick(DialogInterface dialog, int id) { 
            dialog.cancel(); 
           } 
          }); 
      AlertDialog alertDialog = alertDialogBuilder.create(); 
      alertDialog.show(); 
     } 
    }); 
} 

} 

Answer 1

Move инициализация кнопки в методе onCreate , Вы не можете сделать это до этого метода, потому что представление не отображается и элементы не готовы. Изменение кода Java, как следующее:

import android.view.LayoutInflater; 
import android.view.View; 
import android.widget.ArrayAdapter; 
import android.widget.Button; 
import android.widget.Spinner; 

public class Text extends AppCompatActivity { 
    Context context; 
    Button button; 

protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.text_wall); 
    Spinner spinner = (Spinner) findViewById(R.id.LanguagePicker); 
    button = (Button) findViewById(R.id.ConfirmationButton); 
    context = this; // why this? why using context when u have this? 


    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, 
      R.array.language, android.R.layout.simple_spinner_item); 

    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 

    spinner.setAdapter(adapter); 
    button.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      LayoutInflater li = LayoutInflater.from(context); 
      View promptsView = li.inflate(R.layout.alertdialog, null); 

      AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
        context); 


      alertDialogBuilder.setView(promptsView); 
      alertDialogBuilder 
        .setCancelable(false) 
        .setPositiveButton("OK", 
          new DialogInterface.OnClickListener() { 
           public void onClick(DialogInterface dialog,int id) { 

            Spinner spinner = (Spinner) findViewById(R.id.LanguagePicker); 
            String text = spinner.getSelectedItem().toString(); 
           } 
          }) 
        .setNegativeButton("Cancel", 
          new DialogInterface.OnClickListener() { 
           public void onClick(DialogInterface dialog, int id) { 
            dialog.cancel(); 
           } 
          }); 
      AlertDialog alertDialog = alertDialogBuilder.create(); 
      alertDialog.show(); 
     } 
    }); 
} 

} 

В проверке наркомании, если ваша деятельность присутствует в манифесте. если не опубликовать полный манифест, пожалуйста,